A new scientific report published by a team of researchers at the US-based Health Effects Institute found that even low levels of air pollution, well below the current national regulatory cutoffs — may harm human health. The report included Medicare demographic and mortality data from more than 68 million older Americans from all but two states across the US over a 16-year period, adjusting many factors known to affect health, such as socioeconomic status, smoking, and body mass index. The authors wrote that death rates rose by 6 to 8 percent for each incremental increase in PM2.5 exposure between 2000 and 2016.