After years of headlines about air pollution, we’ve been misled on a few things about the world’s biggest environmental health problem. For example, we’re told that “PM2.5” – solid pollution particles measuring 2.5 micrometres or less – can pass through our lungs and into our blood stream.
But, in fact, the vast majority of them can’t.
We’ve also been told NOx gases – including nitrogen dioxide – are the biggest threat to health within cities. However, NOx is responsible for just 14% of deaths attributed to air pollution in Europe.
The biggest killer of all never makes the headlines, isn’t regulated, and is barely talked about beyond niche scientific circles (despite their best efforts to change that narrative): it’s nanoparticles.
PM2.5 may be too small to see, being roughly 30 times smaller than the width of a human hair. But, compared to a nanoparticle it’s a relative heavyweight. PM2.5 stomps in at 2,500 nanometres (nm), while the real killers are 100nm or below. This issue is that local authorities consider PM2.5 and any particle smaller than it to be the same – which means that often their reports underrepresent the true risks. Link