My Own Private Venus
February 14, 2007 7:03 PM   Subscribe

How can I reduce CO2 levels in my house?

My girlfriend brought a professional air quality monitor home from work, and the CO2 level in the house is over 900ppm (1000ppm is a common regulatory threshold). This is surprising considering how drafty the house is, but it's a fairly small house with two people and a dog. It's too cold to keep doors and windows open -- is there another way to keep the CO2 level below brain-clouding concentrations?
posted by bjrubble to Health & Fitness (11 answers total)
Is your house a gas-burning place? Are you certain that your stove, water heater, and furnace all vent correctly? I dunno squat about such things, but that seems like the obvious place to start.

Also, have you checked your CO levels?
posted by TheNewWazoo at 7:13 PM on February 14, 2007


1. Carbon Dioxide
2. Sunlight
3. ????*
4. Oxygen!

* photosynthesis
posted by CKmtl at 7:25 PM on February 14, 2007 [2 favorites]

Well, you could stop breathing. Or you could open a window.

You're running in terror from shadows. I don't believe that the 1000 PPM number.

According to the Material Safety Data Sheet for gaseous CO2, the OSHA long term Permissible Exposure Limit (PEL) is 5000 PPM. The Short Term permissible exposure limit is 30,000 PPM. (OSHA is the Occupational Safety and Health Administration.)

The human LC50 is 100,000 PPM. LC50 means "lethal concentration 50%", a concentration that will kill 50% of humans.

900 PPM represents no hazard whatever.
posted by Steven C. Den Beste at 7:30 PM on February 14, 2007

You can perform some experiments to determine if you're really getting the right data, and whether the data is meaningful.

* Go outside and measure.
* Close all the windows and measure inside.
* Open all the windows and measure inside.
* Turn off everything that's burning inside and measure.
* Go somewhere else outside, far from your neighborhood, and measure.
* Go to someone else's house and measure.
* Go get a different monitor and do the same measurements.
* Compare the results.

Obviously, if outside = inside, then there's nothing you can do. ;-)
posted by frogan at 7:45 PM on February 14, 2007

Just to eliminate the obvious: it wasn't given to her because it was out of cal or otherwise broken, was it? Also, what's the operating range of the detector? If the calibration is for say, 5000-50000 ppm, a reading of 900 may mean "zero, plus or minus a bit." If one or both of you know how to use the equipment properly, then disregard. I don't know anything about CO2 monitors, just calibrated equipment in general.

As to your actual question: I guess your ventilation system (if any) can't be cranked up without the heating being able to keep up? You might want to check the radon level, too.
posted by ctmf at 11:12 PM on February 14, 2007

Response by poster: Thanks for the feedback. A couple of responses:
* My girlfriend does this professionally. The machine is working and calibrated.
* The actual regulations are more complicated (700ppm over the outside concentration) but 1000ppm is higher than ideal.
* I'm in law school and study a lot at home, so even if it's not dangerous I don't want my brain clouded.
* I have lots of houseplants (including a few phylodendrons).

It sounds like I should just step outside once in a while...
posted by bjrubble at 8:39 AM on February 15, 2007

That kind of concentration won't "cloud your brain". It won't affect you in the slightest.

You're treating CO2 as if it's some sort of poison. It isn't. The only reason that CO2 becomes dangerous is that it's a metabolic waste we excrete (in our breath) and if there's too much of it in the air around us we can't get rid of it in our breath, so it builds up in our blood. But the safe range is quite broad, and even if it starts to build up in your blood it doesn't damage anything until the level becomes quite high.

And long before it does you'll feel distinctly uncomfortable. You'll find yourself panting, and you'll have an overwhelming urge to leave the vicinity.

But that requires concentrations 50 times what you're measuring. The levels you're finding represent no hazard at all. They will have no effect on you whatever.

Are you perhaps confusing carbon dioxide with carbon monoxide? Those are entirely different things. Carbon monoxide definitely is a problem even in low concentrations, but carbon dioxide is a normal part of our environment even in concentrations well beyond what you've found.
posted by Steven C. Den Beste at 9:25 AM on February 15, 2007

Response by poster: SCDB, not to be prickly, but please don't treat me like an idiot. You may be correct that these levels of CO2 will have no effect whatever, but I'm disinclined to take this assurance seriously when you follow this with the suggestion that I don't know the difference between CO2 and CO.

The regulatory limits are based on actual physiological danger. My concern is that I'm spending several hours reading dense material in conditions that are bordering on what is considered to constitute a "sick building." I haven't seen anything on the effects of elevated (but not toxic) levels of CO2 on mental performance -- if you have this data, please present it -- but elevated CO2 is also considered a general indication of poor ventilation, which presents the possibility of high levels of other measurable and unmeasurable pollutants.
posted by bjrubble at 12:02 PM on February 15, 2007

elevated CO2 is also considered a general indication of poor ventilation

These people don't seem to think so.

If you have double-layered windows, you may be able to get some fresh air in by cracking the exterior set at the bottom and the interior set at the top... it'd still let some cold in, but at least it would cut the wind.
posted by CKmtl at 1:16 PM on February 15, 2007

When light is not shining on them, most plants (cacti are an exception) absorb oxygen and give off carbon dioxide, just like we do. Another possible source of CO2 is the soil your houseplants are rooted in, but I couldn't find numbers for you.
posted by jamjam at 2:24 PM on February 15, 2007

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