Study Links Air Pollution To Higher COVID-19 Death Rate

A Harvard study determined COVID-19 patients who lived in regions of the United States with higher levels of air pollution before the pandemic are at a higher risk of dying from the disease than those who live in areas with cleaner air. The nationwide study, conducted by Harvard’s T.H. Chan School of Public Health, was the first to demonstrate a clear link between long term exposure to pollution and high risk of death from COVID-19.

The study analyzed over three thousand counties in the United States to determine that higher levels of fine particulate air pollution (PM2.5) were associated with higher death rates from COVID-19. This type of air pollution is mostly generated from fuel combustion from cars, refineries and power plants. The study adjusted for variables such as population size, number of hospital beds, availability of testing for COVID-19, and weather. In addition, socioeconomic and behavioral variables such as obesity and smoking were taken into account. Even so, long term exposure to PM2.5 leads to a significant increase in the death rate from COVID-19.

The study found that “someone who lives for decades in a county with high levels of fine particulate pollution is 8%* more likely to die from COVID-19 than someone who lives in a region that has just one unit (one microgram per cubic meter) less of such pollution.” According to study author Francesca Dominici, Clarence James Gamble Professor of Biostatistics, Population and Data Science at the Harvard Chan School, this means that the areas with higher pollution levels will be guaranteed more “hospitalizations, higher numbers of deaths and [will be] where many of the resources should be concentrated.”

The Harvard study is one of a small group of studies that demonstrate how breathing dirty air, particularly over a long period of time, can make people more vulnerable to severe cases of COVID-19. The majority of these studies have been conducted in Europe, but the body of research is growing larger. Dr. Dominici of the Harvard Chan School, and other public health experts, suggest that results of this study and others like it mean that people who live in areas like the Central Valley of California must be ready for more severe cases of COVID-19 than in, for example, more coastal areas of California.

The Harvard study did not analyze individual patient data. It did not attempt to answer why some general areas of the country have been hit harder than others or at different times than others, and it is not clear whether or not fine particulate matter pollution helps to spread COVID-19 or not. The study did not determine whether fine particulate matter pollution leads to a greater risk of falling ill, it only determined that it leads to more severe cases and a greater risk of death. This finding is of particular concern to hospitals in poor neighborhoods and communities of color, which tend to be exposed to higher levels of air pollution than affluent and/or white communities, according to Dr. John R. Balmes, a spokesman for the American Lung Association.

These studies support other connections between PM2.5 exposure increased death risk from other cardiovascular and respiratory conditions. The researchers emphasize the need for continued enforcement of air pollution regulations in order to protect human health both during the COVID-19 pandemic and after it fades from view.