Mar 14, 2019

The unequal burden of air pollution

Adapted from Tessum et al., 2019, “Inequity in consumption of goods and services adds to racial-ethnic disparities in air pollution exposure”; Chart: Chris Canipe/Axios

Exposure to air pollution in the U.S. is unevenly distributed, with the white population causing much of the pollution that black and Hispanic populations breathe in, a thought-provoking and novel new study found.

Why it matters: Fine particulate matter is responsible for 63% of environment-related deaths in the U.S. each year, adding up to around 100,000 deaths. Previous research has examined the ties between income and pollution exposure, and it has long been known that the location of pollution sources — such as coal-fired power plants and factories — tend to be in or upwind of poor neighborhoods that have a greater concentration of minorities.

However, this new research is the first to comprehensively analyze the gap between who generates pollution and who breathes it in.

Background: The study, by a group of engineers and economists, focuses on fine particulate matter, known as PM2.5, tiny particles smaller than the width of a human hair that can easily be breathed in and get lodged deep into the lungs. Such particles can cause cardiovascular problems, aggravate pre-existing conditions like asthma, and increase mortality from cancer, strokes and heart disease.

What they did: The study, published in Proceedings of the National Academy of Sciences on Monday, first estimates mortality from PM2.5 for the U.S. as a whole for all emission sources.

  • Next, the researchers tied these emissions to the end-use activities and end-user parties responsible for generating this pollution.
  • The team compared the types of goods and services people spend their money on to the amount and geographic distribution of these activities.
  • Lastly, they compared results among racial and ethnic groups to calculate a metric known as "pollution inequity," which they define as "the extent to which groups disproportionately contribute to or bear the burden of pollution."
  • More simply, this metric is the difference between the pollution that people cause and the pollution to which they are exposed.

What they found: The study found that the black population has a pollution inequity of 56%, while Hispanics (in this study, people of all races who are Hispanic or Latino) have a pollution inequity of 63%. The white population and other races, on the other hand, are exposed to 17% less PM2.5 pollution than they contribute and therefore enjoy a "pollution advantage."

  • The study zeroes in on the role that the amount of personal consumption of goods and services (everything from going out to restaurants to buying a new house) plays in causing this pollution imbalance.
  • They found that the quantity of consumption accounts for the majority of the overall pollution imbalance between all races and ethnicities studied.

Meanwhile: Exposure to PM2.5 has decreased among all ethnic groups during the 2003–2015 study period, which is a sign that clean air rules are succeeding. However, racial and ethnic inequities are persisting.

What they're saying: “Someone had to make the pen you bought at the store. We wanted to look at where the pollution associated with making that pen is located. Is it close to where people live? And who lives there?” said co-author Julian Marshall in a press release.

"They certainly make assumptions in their analysis that might be questioned down the line, but I doubt that the overall pattern they found will change," Ana Diez Roux, an epidemiologist at Drexel University who was not involved in the study, told NPR.

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