Pedestrians in Beijing, which was shrouded in polluted air after a sandstorm in March 2021. Hundreds of millions of people around the world are breathing dirty air that far exceeds health guidelines, and climate change is making pollution worse, according to a new report that analyzed real-time air quality data from tens of thousands of monitoring stations. Those sensors measured levels of PM2.5 , particulate matter 2.5 micrometers and smaller in length that’s found in vehicle exhaust, power plant emissions, desert dust storms and smoke from cooking stoves and wildfires. Scientists have linked exposure to PM2.5 with heart and lung disease and 7 million premature deaths each year. In September 2021, the World Health Organization issued guidelines that cut acceptable annual exposure to PM2.5 in half, to 5 micrograms per cubic meter of air. No country achieved that strict standard in 2021, according to the report released Tuesday by […]