It takes hours for carbon monoxide to leave your body
That means low exposure over a long period of time can be a serious problem.
“Once inhaled, carbon monoxide passes from your lungs into your bloodstream, where it attaches to the hemoglobin molecules that normally carry oxygen. Oxygen can’t travel on a hemoglobin molecule that already has carbon monoxide attached to it. As exposure continues, the gas hijacks more and more hemoglobin molecules, and the blood gradually loses its ability to carry enough oxygen to meet your body’s needs. … In fresh air, it takes four to six hours for a victim of carbon monoxide poisoning to exhale about half of the inhaled carbon monoxide in their blood.”
Those quotes are from Harvard Health.
I only learned about this recently, from an episode of The Sharp End podcast. (The podcast is ok overall… good for adventurers. This particular episode got a bit repetitive.)
“For cleaner air, set car vents to ‘recirculate'”
I used to usually turn off the “recirculate air” button in my car until some years ago when I read an article in the LA Times. Since then I’ve tended to leave “recirculate air” on.
“Using that setting…can cut pollution concentrations inside a typical car to 20% of on-road levels.”
“Particle pollution is linked to respiratory illness, heart disease, cancer and premature death.”
“There’s one downside to keeping the windows up and using recycled air, especially if you’re carpooling: It can get stuffy. That’s a product of carbon dioxide from breathing, which can build up on longer drives in tightly sealed new cars with several passengers, according to the study.
‘To prevent this, outside air should be pulled in every 10 or 15 minutes for a minute or two, especially if there are two or more people in the vehicle'”
It makes me think that car review websites should measure and publish air filtration quality. I would take it into account when car shopping.
Classroom air filters might improve test scores
A study indicates that installing air filters in classrooms improved test scores. For more, see the Vox writeup or the original paper.
Another Vox article has a good collection of info about how poor air quality affects cognitive ability.