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 analysed 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 Organisation issued guidelines that cut acceptable annual exposure to PM2.5 in half, to five micrograms per cubic metre of air. No country achieved that strict standard in 2021, according to the report released on Tuesday by IQAir, a Swiss company that makes air quality monitors and air purification technologies...