Health benefits that have resulted from reductions in fine particulate air pollution aren’t distributed equally among populations in the U.S., a new Yale-led study finds. Racial and ethnic minorities — and Black people in particular — still experience disproportionately high rates of cardiovascular disease-related deaths caused by exposure to fine particulate matter, according to the research.
Fine particulate matter, also known as PM2.5, consists of particles or droplets smaller than 2.5 micrometers in diameter, or 30 times smaller than the width of a human hair. While some PM2.5 in the environment comes from natural sources, such as wildfires, the majority of particulate matter pollution in the U.S. is the result of human activities, including emissions from vehicles, power plants, and factories.
“When you inhale such small particles, they can get into your lungs and some smaller particles can even get into the blood stream and circulate around the body,” said Kai Chen, assistant professor of epidemiology at Yale School of Public Health and senior author of the study. “That can impact your heart, which leads to a lot of the cardiovascular disease we see today.”
For the study, the researchers collected data on cardiovascular disease deaths and monthly PM2.5 concentrations across 3,103 counties in the contiguous U.S. between 2001 and 2016. They then evaluated whether there was a link between increases in PM2.5 levels and changes in cardiovascular disease-related deaths.
The results showed that overall, an increase of one microgram per square meter in average PM2.5 levels was associated with 2.01 additional cardiovascular disease-related deaths per 1 million people. But when the researchers took a closer look at the data, they found that the human costs vary in different populations: the same increase in the average PM2.5 levels was associated with 1.76 additional deaths per 1 million White people, 2.66 additional deaths per 1 million Hispanic people, and 7.16 additional deaths per 1 million Black people. On average, there were 202.70 deaths per 1 million White people, 279.24 deaths per 1 million Hispanic people, and 905.68 deaths per 1 million Black people each year.
“Poor air quality imposes a substantial burden on Black Americans, with greater exposures and greater vulnerability,” said co-author Harlan Krumholz, the Harold H. Hines, Jr. Professor of Medicine at Yale School of Medicine. “We have identified another way that the structure of our society contributes to cardiovascular health disparities. The study demonstrates that the excess mortality among Black people is not just derived from traditional risk factors, but likely also to the increased exposure to poor air quality based on where they live.”