The link between air pollution exposure and risk of premature death is well known to epidemiologists—according to one study, in 2015 alone, air pollution killed about 4.2 million people worldwide. Two large studies from China have now provided further evidence of how such exposure increases the risk of specific and acute health problems. Most such studies have been done in high-income countries and used relatively small samples. The new studies, both led by researchers at Huazhong University of Science and Technology, focused on fine particulate matter pollution, or PM2.5. The first study, led by Yonghua Hu, investigated the relationship between daily PM2.5 concentrations and 8.83 million hospital admissions of people with cardiovascular disease in 184 Chinese cities between 2014 and 2017 (BMJ 2019, DOI: 10.1136/bmj.l6572). At the national level, an average increase of 10 μg/m3 in daily concentration of PM2.5 was associated with a 0.26% increase in hospital admissions on the same day for cardiovascular diseases, including heart failure, stroke, and restricted blood flow to the heart. The second study, led by Dongfeng Gu, examined 3,540 hospitalizations due to stroke from 2000 to 2015. Gu’s team found that each increase of 10 μg/m3 in PM2.5 concentration led to a 13% higher risk of stroke (BMJ 2019, DOI: 10.1136/bmj.l6720).