No Limit?

PM2.5s are Particulate Matter with an average diameter of 2.5 microns. These tiny soot particles, are released into the air by diesel engines; factories; wildfires as well as fashionable wood-burning stoves in up-market areas of London. High levels of PM2.5s are predictably found by busy roads in major cities. This form of atmospheric pollution has long been known to have profound detrimental effects on human health. It increases chronic repiratory and cardiovascular disease as well as reducing longevity. Two recent substantial studies now essentially confirm there's no such thing as a 'safe level' of PM2.5s (https://www.theguardian.com/environment/2024/feb/21/air-pollution-quality-harmful). Even small exposures to PM2.5s increased the risk of cardiovascular disease in EU; UK and US populations. Many locations in these countries frequently exceed WHO-specified levels of particulates. PM2.5 levels are dramatically higher in some other countries (like China and India). Particulates need to be largely eliminated, if human health matters to society! This means creating and policing clean air zones. It's not going to be easy, as this form of pollution is only hazy. Emitters see it as vanishing into the air.