There was a recent discussion about excessive CO2 levels in the soil. Although CO2 is not a radon issue, ventilation in buildings is an important factor in maintaining air quality and ultimately radon levels. We are also moving towards tighter and tighter building shells and often are not being concerned with how this affects air quality. Dave Wilson has documented whole developments that have 10% of the units with radon that all get remediated. Five years later the same development gets retested and a new 10% of the units turn up with elevated radon. Sometimes the explanation is the development had weatherization done without any additional ventilation. But in general all homes are getting more air tight and ventilation in these homes is typically not considered.

Obviously as our buildings get tighter without adding ventilation CO2 levels start climbing and now that the percentage of homes have AC and Heating systems the homeowners often never open any windows. The issue is the affect of small increases in CO2 on worker performance has been studied and found to be very significant. Check out this recent study that comes up when you google CO2 levels and performance. There are other studies which most demonstrate an affect on cognitive performance when CO2 levels rise.

https://thinkprogress.org/exclusive-elevated-co2-levels-directly-affect-human-cognition-new-harvard-study-shows-2748e7378941/

There will be a presenter at the Denver AARST conference talking about the affect of CO2 and the concept of increasing outdoor air into homes. I would highly encourage everyone to purchase an inexpensive CO2 monitor and plug it at your office or home. You will be shocked how much the CO2 levels shoot up in any room that is occupied without ventilation. This unit is less than $100

https://www.amazon.com/Hydrofarm-Autopilot-Desktop-Monitor-Logger/dp/B01FYWU2IS/ref=sr_1_3?keywords=co2+monitor&qid=1562085098&s=gateway&sr=8-3

In my own office which is not very large, the CO2 levels would climb to 1500 ppm and higher when 3 of us were working. Shocking when you read a study that CO2 increases of as little as 400 ppm caused a 20% decrease in cognitive performance. I have a portable CO2 monitor and in my car the CO2 levels would climb to 2000 ppm if the air was on re-circulating. Could this be a factor in car accidents?

As we move towards an increasing CO2 level in our outdoor air this is an important area to be educated on.