Global Study Reveals There's No Place on Earth You Can Be Fully Safe From Deadly Air Pollutants

PM2.5 is an air pollutant consisting of both solid microparticles and the smallest liquid droplets of about 10 nm to 2.5 μm. PM2.5 readily penetrates biological barriers and therefore poses the greatest threat to the body, with a new study suggesting that the size of the hazard may be greater than previously thought.