# CO2, higher concentration in an open cellar? **URL:** \ **Category:** Factual Questions\ **Created:** [November 20, 2002, 5:23am UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703 "2002-11-20T05:23:53Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![aeroponica](https://avatars.discourse-cdn.com/v4/letter/a/839c29/32.png) [@aeroponica](https://boards.straightdope.com/u/aeroponica)\ **Post date:** [November 20, 2002, 5:23am UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/1 "2002-11-20T05:23:53Z")
I am an indoor gardening fanatic. C02 is heavier than air and essential to plant growth. I’ve considered cutting two holes from the floor in my garden room through to the cellar below, serving two purposes; the first being a heat vent and second as an uptake for fresh air and hopefully higher concentrations of C02 than could be supplied by a first-story window. The cellar has several open vents and an open doorway but smells of stagnant water and mildew. I live in a heavily forested area with lush greenery that grows up to 15ft. from my home. Is it possible that higher or lower than average concentrations of C02 might exist in my cellar at an extreme that merits special consideration? Thank you, Aeroponica ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 20, 2002, 8:36am UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/2 "2002-11-20T08:36:28Z")
If you want to increase the concentration of CO[sub]2[/sub] in a space, couldn’t you just light a candle? (A scented one might help with the odour too). ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [November 20, 2002, 1:24pm UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/3 "2002-11-20T13:24:43Z")
live in the green house. Or just buy some solid CO2 and dump on the floor. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 20, 2002, 1:31pm UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/4 "2002-11-20T13:31:46Z")
It’s also worth noting that plants need oxygen too; not that you’re likely to build up an environment that excludes it completely. Plants respire just like we do; it just happens that when they are exposed to light, photosynthesis (a completely separate process to respiration) results in a surplus of oxygen. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 20, 2002, 2:08pm UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/5 "2002-11-20T14:08:47Z")
I doubt that you’ll build up much of a CO[sub]2[/sub] concentration in a cellar, unless it’s walled with limestone or has an improperly vented gas furnace. Here’s a nice link which gives descriptions of the common [methods of CO[sub]2[/sub] fertilization](http://www.hydromall.com/grower/suite101/co2.html) . You need to be a bit careful about how much CO[sub]2[/sub] you add to your room, as levels above 1000 ppm can [damage your plants](http://www.rockwool.com/sw4568.asp). You may find more useful information in the results of these searches : [(“co2 fertilization” -climate -aquarium -animals -aquatic)](http://www.google.com/search?q=+%22co2+fertilization%22+-climate+-aquarium+-animals+-aquatic&hl=en&lr=&ie=UTF-8&safe=off&as_qdr=all&start=20&sa=N) [( “co2 toxicity” plants)](http://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&as_qdr=all&q=+%22co2+toxicity%22+plants&btnG=Google+Search) ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 20, 2002, 2:13pm UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/6 "2002-11-20T14:13:43Z")
CO2 isn’t so dense that it separates from the air and pool in low places. If it were, there would be significantly less CO2 on top of mountains. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 20, 2002, 3:22pm UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/7 "2002-11-20T15:22:02Z")
> [@](#): > > CO2 isn’t so dense that it separates from the air and pool in low places It doesn’t separate from air easily, but the reactions that produce CO[sub]2[/sub] make it a high concentration, and _already_ separated from the bulk of the atmosphere. This form of CO[sub]2[/sub] pools quite readily. It’s one of the main reasons mines and tunnels need to be ventilated. If the air is still, CO[sub]2[/sub] will also pool in low spots and in basements. This article on [CO[sub]2[/sub] induced tree kills](http://wrgis.wr.usgs.gov/fact-sheet/fs172-96/) in the long valley caldera tells us: > [@](#): > > When CO[sub]2[/sub] from soil leaves the ground, it normally mixes with the air and dissipates rapidly. CO[sub]2[/sub] is heavier than air, however, and it can collect at high concentrations in the lower parts of depressions and enclosures, posing a potential danger to people. Breathing air with more than 30% CO[sub]2[/sub] can very quickly cause unconsciousness and death. Therefore, poorly ventilated areas above and below ground can be dangerous in areas of CO[sub]2[/sub] seepage. ---
**Author:** ![aeroponica](https://avatars.discourse-cdn.com/v4/letter/a/839c29/32.png) [@aeroponica](https://boards.straightdope.com/u/aeroponica)\ **Post date:** [November 20, 2002, 8:40pm UTC](https://boards.straightdope.com/t/co2-higher-concentration-in-an-open-cellar/137703/8 "2002-11-20T20:40:19Z")
Thank you everyone for responding. > [@](#): > > _Originally posted by Mangetout_ > **If you want to increase the concentration of CO2 in a space, couldn’t you just light a candle? (A scented one might help with the odour too).** High maintainence. I am trying to minimize my daily must-doos > [@](#): > > \*Originally posted by scr4 \* > \*\*CO2 isn’t so dense that it separates from the air and pool in low places. If it were, there would be significantly less CO2 on top of mountains. \*\* Tree line. > [@](#): > > \*Originally posted by Shalmanese \* > **Or just buy some solid CO2 and dump on the floor.** Not a bad idea. They actually give it away at my local Co-Op. Any idea how long a brick lasts? **Squink** , thank you for all the great links. I am looking into renting a CO2 tester. Who knows for sure unless I test, right? Then I can experiment with all the different C02 supplement methods as well. I’ll post the results. Thanks again, Aeroponica