As we clean up large sources of toxic air pollutant exposure in our environment, we are able to find things like this: a study linking exposure to particulate matter and NO2 to cognitive decline: https://bit.ly/43hIzRw
The mean exposure in this study was 6.9 micrograms of particulate matter per cubic meter, and 12.9 parts per billion of nitrogen dioxide, both of which are considerably lower than the US National Air Quality Standards for these pollutants of 15 mcg/m3 for PM2.5 and 53 ppb for NO2.
