If you're in a closed space, you may want to open a window.

before the industrial revolution, the atmosphere had 300 parts-per-million (PPM) of CO2. today, this number is already above 400 on average, and 500 in urban areas.

but CO2 doesn't just effect the environment, high enough levels of it also effect our bodies, and our minds.

so let's leave the atmosphere for a bit, and go inside. one study checked office employee's decision making skills at various CO2 levels, here some of the results:


this level is common at poorly ventilated spaces like a workrooms/offices. and one study on schools in several US districts found 50% of classrooms to have this level.

at this CO2 level the cognitive function in the office experiment decreased by 15%.


this level can also be reached at the places described above.

here cognitive function decreased by 50%!


from this level onward some people described other side effects such as: slight nausea, loss of attention and poor concentration, sleepiness, headaches, and increased hearth rates.

and still, these levels aren't uncommon -


this is common in cars and bedrooms (closed spaces which are either small, you spend a long time in, or both. and the side effects increase.


motorcycle helmets can reach these levels. Being in such an environment for long times can harm your long-term health.

So what can you do?

1. simply open a window! (at least in this part of the century)

2. you can get some plants for your room or office -

The NASA Clean Air Study looked at about two and half dozen plants, and recommends these tree plants: Areca Palm, Snake Plant, and Money Plant.

This lung institute guide seems to be based on this study, so i suggest reading it.

3. buy a CO2 monitor if you want to always know in what environment you're in. though, these seem cost quite a bit (for a reason unclear to me). so i don't know if it will really benefit you. i know i won't bother.

The IPPC reported that CO2 levels will be, by the end of the century, between 541 and 970ppm. if we extrapolate from the previous study, this may mean a 10-15% decrease in the cognitive function of humanity as a species (and even more than the previous results in closed spaces).

some studies found evidence that air pollution can harm the brain itself.

Should this change our attitude towards climate change as a catastrophic risk?

This has been brought to my attention by this video series and this video. give it a look if you want to see for yourself how high CO2 levels affect a person

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This 2018 paper did a nice review of the state of evidence.

See "Rapid evidence assessment on the effects of CO2 on performance"


One local rationalists got a sensor and took it to community events. It lead to those events having the window open much more often. It also had some ripple effects and now I'm opening my own windows at home more often as well.

Unfortunately, CO2 isn't the only air-pollution. It's unfortunate that you can't buy a smart CO2 sensor that measures particle pollution, CO, CO2 and all the variables that are interesting. The fact that you need to buy mulitple devices to get all the relevant values makes me wait for new tech.

Building machines that remove CO2 from the air in office buildings is another business opportunity.

yeah i wrote a line at the end about pollution in general, but talked about CO2 cause that can be emitted just from the breathing process. and also a lot of time CO2 is used as a general metric for pollution, even if it's not the only substance.

the office machine to remove CO2 is really quite interesting actually, it's the first good (or any) idea i heard that makes it worthy for business . i wonder how much effect it can have on the general environment if it were put into practice.

After previous thread I bought CO2 monitor with alarm. It typically is hovering around 600 ppm, not that bad, despite my closed windows. Alarm runs at 1200 and it is happening relatively rare, if have many friends or use gas for cooking. I also have CO alarm and fire alarm.