World can now breathe easier but further mitigation still needed, air pollution study finds

Ambient fine particulate matter (PM2.5) is the world's leading environmental health risk factor. At only 2.5 micrometers or smaller, these particles are small enough to be inhaled and cause respiratory problems, such as asthma and bronchitis, and cardiovascular issues, including heart attacks and high blood pressure. For children, PM2.5 can cause lifelong developmental issues, and for the general population, PM2.5 is associated with premature death.