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		<id>https://www.explainxkcd.com/wiki/index.php?action=history&amp;feed=atom&amp;title=3037%3A_Radon</id>
		<title>3037: Radon - Revision history</title>
		<link rel="self" type="application/atom+xml" href="https://www.explainxkcd.com/wiki/index.php?action=history&amp;feed=atom&amp;title=3037%3A_Radon"/>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;action=history"/>
		<updated>2026-05-22T18:55:06Z</updated>
		<subtitle>Revision history for this page on the wiki</subtitle>
		<generator>MediaWiki 1.30.0</generator>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=403321&amp;oldid=prev</id>
		<title>2600:4040:99D4:8B00:CDD5:BE41:AB9F:66FD: /* Explanation */ two comics in series -&gt; three</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=403321&amp;oldid=prev"/>
				<updated>2026-01-11T19:51:10Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation: &lt;/span&gt; two comics in series -&amp;gt; three&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 19:51, 11 January 2026&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l10&quot; &gt;Line 10:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Explanation==&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Explanation==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This comic was the first in a series (of at least &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;two &lt;/del&gt;comics) about absurd results of [[:Category:Home Inspections|home inspections]]. The second, [[3059: Water Damage]] came out less than two months after this one.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This comic was the first in a series (of at least &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;three &lt;/ins&gt;comics) about absurd results of [[:Category:Home Inspections|home inspections]]. The second, [[3059: Water Damage]] came out less than two months after this one.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, [https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview roughly 2.8 ppm of the planet is made of uranium]; this is about 0.00028% of the planet, which [https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms]. Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, [https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview roughly 2.8 ppm of the planet is made of uranium]; this is about 0.00028% of the planet, which [https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms]. Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>2600:4040:99D4:8B00:CDD5:BE41:AB9F:66FD</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=375635&amp;oldid=prev</id>
		<title>BobcatInABox: /* References */</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=375635&amp;oldid=prev"/>
				<updated>2025-04-29T14:52:38Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;References&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 14:52, 29 April 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l40&quot; &gt;Line 40:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 40:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail (off-panel): Yikes, you built around a short-lived yellow star? What a mess.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail (off-panel): Yikes, you built around a short-lived yellow star? What a mess.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail (off-panel): Hope you have good insurance.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail (off-panel): Hope you have good insurance.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;==References==&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;{{reflist}}&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;{{comic discussion}}&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;{{comic discussion}}&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>BobcatInABox</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=375634&amp;oldid=prev</id>
		<title>BobcatInABox: /* Explanation */</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=375634&amp;oldid=prev"/>
				<updated>2025-04-29T14:52:07Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 14:52, 29 April 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l20&quot; &gt;Line 20:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 20:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The Sun is an example of a G-type {{w|main sequence}} star, also known as a yellow dwarf, which the inspector notes is a short-lived star. In the next 1 billion years the Sun will {{w|Sun#Main_sequence|become more luminous and end life on Earth}}, and in 4 to 7 billion years the Sun's outer layers will expand, turning it into a red giant that will likely {{w|Sun#After_core_hydrogen_exhaustion|engulf the Earth}}. If we'd 'built' around an M-type red dwarf we could have comfortably waited for the uranium to fully decay, though being in the habitable zone of a red dwarf [https://aasnova.org/2016/09/14/are-stellar-storms-bad-news-for-m-dwarf-planets/ has its own difficulties]. &amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The Sun is an example of a G-type {{w|main sequence}} star, also known as a yellow dwarf, which the inspector notes is a short-lived star. In the next 1 billion years the Sun will {{w|Sun#Main_sequence|become more luminous and end life on Earth}}, and in 4 to 7 billion years the Sun's outer layers will expand, turning it into a red giant that will likely {{w|Sun#After_core_hydrogen_exhaustion|engulf the Earth}}. If we'd 'built' around an M-type red dwarf we could have comfortably waited for the uranium to fully decay, though being in the habitable zone of a red dwarf [https://aasnova.org/2016/09/14/are-stellar-storms-bad-news-for-m-dwarf-planets/ has its own difficulties]. &amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The title text for this comic mentions an {{w|umbrella insurance|umbrella policy}}, a type of insurance policy that covers damages beyond those covered by another, primary policy. It makes a joke with the isotope representation of uranium-238 being &amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U, and is something that Cueball might need to consult with after handling the issue of radon gas in his home; &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;most states in the United States, for instance, require property disclosure forms to be filled out if radon levels surpass a certain threshold.&amp;lt;ref&amp;gt;&lt;/del&gt;https://www.eli.org/sites/default/files/files-pdf/Final%202022%20Radon_0.pdf&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;&amp;lt;/ref&amp;gt; &lt;/del&gt;This text may also be an oblique reference to the concept of a {{w|nuclear umbrella}}, an altogether different kind of &amp;quot;insurance&amp;quot;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The title text for this comic mentions an {{w|umbrella insurance|umbrella policy}}, a type of insurance policy that covers damages beyond those covered by another, primary policy. It makes a joke with the isotope representation of uranium-238 being &amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U, and is something that Cueball might need to consult with after handling the issue of radon gas in his home; &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;[&lt;/ins&gt;https://www.eli.org/sites/default/files/files-pdf/Final%202022%20Radon_0.pdf &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;most states in the United States, for instance, require property disclosure forms to be filled out if radon levels surpass a certain threshold]. &lt;/ins&gt;This text may also be an oblique reference to the concept of a {{w|nuclear umbrella}}, an altogether different kind of &amp;quot;insurance&amp;quot;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Transcript==&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Transcript==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>BobcatInABox</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=375631&amp;oldid=prev</id>
		<title>BobcatInABox: /* Explanation */</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=375631&amp;oldid=prev"/>
				<updated>2025-04-29T14:50:05Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 14:50, 29 April 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l12&quot; &gt;Line 12:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 12:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This comic was the first in a series (of at least two comics) about absurd results of [[:Category:Home Inspections|home inspections]]. The second, [[3059: Water Damage]] came out less than two months after this one.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This comic was the first in a series (of at least two comics) about absurd results of [[:Category:Home Inspections|home inspections]]. The second, [[3059: Water Damage]] came out less than two months after this one.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;roughly 2.8 ppm of the planet is made of uranium;&amp;lt;ref&amp;gt;&lt;/del&gt;https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;&amp;lt;/ref&amp;gt; &lt;/del&gt;this is about 0.00028% of the planet, which &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms.&amp;lt;ref&amp;gt;&lt;/del&gt;https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html&amp;lt;/&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;ref&lt;/del&gt;&amp;gt; Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;[&lt;/ins&gt;https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;roughly 2.8 ppm of the planet is made of uranium]; &lt;/ins&gt;this is about 0.00028% of the planet, which &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;[&lt;/ins&gt;https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;weighs about 5.9722×10&amp;lt;sup&amp;gt;24&lt;/ins&gt;&amp;lt;/&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;sup&lt;/ins&gt;&amp;gt; &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;kilograms]. &lt;/ins&gt;Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>BobcatInABox</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=371224&amp;oldid=prev</id>
		<title>172.70.255.149: Changed 'home' to 'house' in the transcript, rest seems fine enough.</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=371224&amp;oldid=prev"/>
				<updated>2025-04-03T16:21:23Z</updated>
		
		<summary type="html">&lt;p&gt;Changed &amp;#039;home&amp;#039; to &amp;#039;house&amp;#039; in the transcript, rest seems fine enough.&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 16:21, 3 April 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l23&quot; &gt;Line 23:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 23:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Transcript==&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Transcript==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;{{incomplete transcript|Do NOT delete this tag too soon.}}&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:[Cueball is on the left and is approached by Ponytail, who is reading a Geiger counter in her hand and holding a toolbox in her other hand.]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:[Cueball is on the left and is approached by Ponytail, who is reading a Geiger counter in her hand and holding a toolbox in her other hand.]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail: Radon levels in your basement are pretty high.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail: Radon levels in your basement are pretty high.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail: When was the planet under this &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;home &lt;/del&gt;built?&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:Ponytail: When was the planet under this &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;house &lt;/ins&gt;built?&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:[Ponytail stops walking and lowers the Geiger counter.]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:[Ponytail stops walking and lowers the Geiger counter.]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>172.70.255.149</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=371068&amp;oldid=prev</id>
		<title>172.71.148.24: /* Explanation */ Remove one cn tag(this doesn't need a citation as it's trivially true). Move the other cn tag behind the comma.</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=371068&amp;oldid=prev"/>
				<updated>2025-04-02T01:25:50Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation: &lt;/span&gt; Remove one cn tag(this doesn&amp;#039;t need a citation as it&amp;#039;s trivially true). Move the other cn tag behind the comma.&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 01:25, 2 April 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l16&quot; &gt;Line 16:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 16:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;But rather than inquire about the age of the home, Ponytail asks about the age of the planet on which it was built. The answer would be the same for all houses on Earth.&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;{{cn}} &lt;/del&gt;Apparently she's an interstellar inspector, testing properties on many different planets in different star systems with different levels of radon - since most planets in a given system form within a few million years of each other and would have similar levels of radon. Earth's age of 4.5 billion years is about the same as the half-life of U-238, so radon levels are high because much of the original uranium is still in the process of decaying. She recommends waiting 100 billion years - much longer than the expected lifetime of Cueball{{&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;citation needed&lt;/del&gt;}}&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;, &lt;/del&gt;the building, and the Sun as we know it - enough to cause U-238 to decay to a trivial amount, not factoring in other daughter nuclides due to their comparatively shorter half-life.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;But rather than inquire about the age of the home, Ponytail asks about the age of the planet on which it was built. The answer would be the same for all houses on Earth. Apparently she's an interstellar inspector, testing properties on many different planets in different star systems with different levels of radon - since most planets in a given system form within a few million years of each other and would have similar levels of radon. Earth's age of 4.5 billion years is about the same as the half-life of U-238, so radon levels are high because much of the original uranium is still in the process of decaying. She recommends waiting 100 billion years - much longer than the expected lifetime of Cueball&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;,&lt;/ins&gt;{{&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;cn&lt;/ins&gt;}} the building, and the Sun as we know it - enough to cause U-238 to decay to a trivial amount, not factoring in other daughter nuclides due to their comparatively shorter half-life.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The Sun is an example of a G-type {{w|main sequence}} star, also known as a yellow dwarf, which the inspector notes is a short-lived star. In the next 1 billion years the Sun will {{w|Sun#Main_sequence|become more luminous and end life on Earth}}, and in 4 to 7 billion years the Sun's outer layers will expand, turning it into a red giant that will likely {{w|Sun#After_core_hydrogen_exhaustion|engulf the Earth}}. If we'd 'built' around an M-type red dwarf we could have comfortably waited for the uranium to fully decay, though being in the habitable zone of a red dwarf [https://aasnova.org/2016/09/14/are-stellar-storms-bad-news-for-m-dwarf-planets/ has its own difficulties]. &amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The Sun is an example of a G-type {{w|main sequence}} star, also known as a yellow dwarf, which the inspector notes is a short-lived star. In the next 1 billion years the Sun will {{w|Sun#Main_sequence|become more luminous and end life on Earth}}, and in 4 to 7 billion years the Sun's outer layers will expand, turning it into a red giant that will likely {{w|Sun#After_core_hydrogen_exhaustion|engulf the Earth}}. If we'd 'built' around an M-type red dwarf we could have comfortably waited for the uranium to fully decay, though being in the habitable zone of a red dwarf [https://aasnova.org/2016/09/14/are-stellar-storms-bad-news-for-m-dwarf-planets/ has its own difficulties]. &amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>172.71.148.24</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=371067&amp;oldid=prev</id>
		<title>Avrayter: /* Explanation */</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=371067&amp;oldid=prev"/>
				<updated>2025-04-02T01:19:48Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 01:19, 2 April 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l16&quot; &gt;Line 16:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 16:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;But rather than inquire about the age of the home, Ponytail asks about the age of the planet on which it was built. The answer would be the same for all houses on Earth.{{cn}} Apparently she's an interstellar inspector, testing properties on many different planets in different star systems with different levels of radon - since most planets in a given system form within a few million years of each other and would have similar levels of radon. Earth's age of 4.5 billion years is about the same as the half-life of U-238, so radon levels are high because much of the original uranium is still in the process of decaying. She recommends waiting 100 billion years - much longer than the expected lifetime of Cueball, the building, and the Sun as we know it - enough to cause U-238 to decay to a trivial amount, not factoring in other daughter nuclides due to their comparatively shorter half-life.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;But rather than inquire about the age of the home, Ponytail asks about the age of the planet on which it was built. The answer would be the same for all houses on Earth.{{cn}} Apparently she's an interstellar inspector, testing properties on many different planets in different star systems with different levels of radon - since most planets in a given system form within a few million years of each other and would have similar levels of radon. Earth's age of 4.5 billion years is about the same as the half-life of U-238, so radon levels are high because much of the original uranium is still in the process of decaying. She recommends waiting 100 billion years - much longer than the expected lifetime of Cueball&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;{{citation needed}}&lt;/ins&gt;, the building, and the Sun as we know it - enough to cause U-238 to decay to a trivial amount, not factoring in other daughter nuclides due to their comparatively shorter half-life.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The Sun is an example of a G-type {{w|main sequence}} star, also known as a yellow dwarf, which the inspector notes is a short-lived star. In the next 1 billion years the Sun will {{w|Sun#Main_sequence|become more luminous and end life on Earth}}, and in 4 to 7 billion years the Sun's outer layers will expand, turning it into a red giant that will likely {{w|Sun#After_core_hydrogen_exhaustion|engulf the Earth}}. If we'd 'built' around an M-type red dwarf we could have comfortably waited for the uranium to fully decay, though being in the habitable zone of a red dwarf [https://aasnova.org/2016/09/14/are-stellar-storms-bad-news-for-m-dwarf-planets/ has its own difficulties]. &amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The Sun is an example of a G-type {{w|main sequence}} star, also known as a yellow dwarf, which the inspector notes is a short-lived star. In the next 1 billion years the Sun will {{w|Sun#Main_sequence|become more luminous and end life on Earth}}, and in 4 to 7 billion years the Sun's outer layers will expand, turning it into a red giant that will likely {{w|Sun#After_core_hydrogen_exhaustion|engulf the Earth}}. If we'd 'built' around an M-type red dwarf we could have comfortably waited for the uranium to fully decay, though being in the habitable zone of a red dwarf [https://aasnova.org/2016/09/14/are-stellar-storms-bad-news-for-m-dwarf-planets/ has its own difficulties]. &amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Avrayter</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=368161&amp;oldid=prev</id>
		<title>Kynde at 09:42, 7 March 2025</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=368161&amp;oldid=prev"/>
				<updated>2025-03-07T09:42:12Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 09:42, 7 March 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l47&quot; &gt;Line 47:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 47:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;{{comic discussion}}&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;{{comic discussion}}&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[Category:Home Inspections]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Category:Comics featuring Cueball]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Category:Comics featuring Cueball]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Category:Comics featuring Ponytail]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Category:Comics featuring Ponytail]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Kynde</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=368160&amp;oldid=prev</id>
		<title>Kynde: /* Explanation */</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=368160&amp;oldid=prev"/>
				<updated>2025-03-07T09:41:56Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 09:41, 7 March 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l10&quot; &gt;Line 10:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Explanation==&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Explanation==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This comic was the first in a series (of at least two comics) about absurd results of [[:Category:Home Inspections|home inspections]].&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This comic was the first in a series (of at least two comics) about absurd results of [[:Category:Home Inspections|home inspections]]&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;. The second, [[3059: Water Damage]] came out less than two months after this one&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, roughly 2.8 ppm of the planet is made of uranium;&amp;lt;ref&amp;gt;https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview&amp;lt;/ref&amp;gt; this is about 0.00028% of the planet, which weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms.&amp;lt;ref&amp;gt;https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html&amp;lt;/ref&amp;gt; Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, roughly 2.8 ppm of the planet is made of uranium;&amp;lt;ref&amp;gt;https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview&amp;lt;/ref&amp;gt; this is about 0.00028% of the planet, which weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms.&amp;lt;ref&amp;gt;https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html&amp;lt;/ref&amp;gt; Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Kynde</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=368159&amp;oldid=prev</id>
		<title>Kynde: /* Explanation */ Category:Home Inspections - new series category created and added</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&amp;diff=368159&amp;oldid=prev"/>
				<updated>2025-03-07T09:41:06Z</updated>
		
		<summary type="html">&lt;p&gt;‎&lt;span dir=&quot;auto&quot;&gt;&lt;span class=&quot;autocomment&quot;&gt;Explanation: &lt;/span&gt; Category:Home Inspections - new series category created and added&lt;/span&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Revision as of 09:41, 7 March 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l10&quot; &gt;Line 10:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 10:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Explanation==&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Explanation==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;This comic was the first in a series (of at least two comics) about absurd results of [[:Category:Home Inspections|home inspections]].&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot;&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, roughly 2.8 ppm of the planet is made of uranium;&amp;lt;ref&amp;gt;https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview&amp;lt;/ref&amp;gt; this is about 0.00028% of the planet, which weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms.&amp;lt;ref&amp;gt;https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html&amp;lt;/ref&amp;gt; Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238 (&amp;lt;sup&amp;gt;238&amp;lt;/sup&amp;gt;U or U-238), the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, roughly 2.8 ppm of the planet is made of uranium;&amp;lt;ref&amp;gt;https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview&amp;lt;/ref&amp;gt; this is about 0.00028% of the planet, which weighs about 5.9722×10&amp;lt;sup&amp;gt;24&amp;lt;/sup&amp;gt; kilograms.&amp;lt;ref&amp;gt;https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html&amp;lt;/ref&amp;gt; Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is &amp;lt;!--(5.9722×10^24 * 0.00028 * 0.01 =)--&amp;gt; 1.67×10&amp;lt;sup&amp;gt;19&amp;lt;/sup&amp;gt; kilograms of uranium across the entire planet. Thus, radon gas is a relatively commonplace phenomenon, and {{w|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over a long enough time, that is, with the windows and doors closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but this isn't why it accumulates in basements; it mixes completely with air, and does not &amp;quot;settle out&amp;quot; because of its atomic weight or density. Rather, its concentrations are higher in the basement than elsewhere in a building because the basement is adjacent to rock and the house foundation where it is generated, and because of the relatively poor air circulation usual in basements. Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Kynde</name></author>	</entry>

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