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Hyperlocal air pollution analysis shows health inequities

Rates of asthma and mortality attributable to air pollution vary among Bay Area neighborhoods

by Katherine Bourzac
April 8, 2021 | A version of this story appeared in Volume 99, Issue 13


A photo of a child taking an asthma inhaler.
Credit: Shutterstock
In some San Francisco Bay Area neighborhoods, air pollution causes half of new childhood asthma cases.

An analysis of the San Francisco Bay Area details how the health and mortality burdens of exposure to air pollution vary among neighborhoods—and shows that people of color bear much of those burdens (Environ. Health Perspect. 2021, DOI: 10.1289/EHP7679). This kind of information will help policy makers design regulations and other interventions for the most vulnerable neighborhoods, the study’s authors say.

Researchers can usually study air pollution’s health impacts only on a state or county level, says Veronica Southerland, a PhD student in environmental health at George Washington University. Exposure to pollutants, including nitrogen dioxide, is known to increase the risk of asthma and death. But because some air pollution disperses rapidly, its health effects are often highly localized and difficult to measure. Thanks to new technologies, that’s changing.

The new study is the first to pair street-by-street air pollution measurements with detailed health records to attribute outcomes—including childhood asthma cases and premature death—to exposure to pollutants, including NO2 and fine particulate matter (PM2.5).

Southerland’s team included a researcher from the Alameda County Public Health Department, who helped provide anonymous health information. The group drew on US Census Bureau data for demographic information. Sensor-equipped cars measured air pollution around Oakland, California, from 2015 to 2017 at a resolution of 100 m. The team also used air pollution readings from other sources, including satellites.

The study finds that every year in the Bay Area, PM2.5 pollution causes over 3,000 deaths and 5,500 childhood asthma cases. NO2 exposure is linked to 2,500 annual deaths and 5,200 new childhood asthma cases annually. The intracity analysis allowed other insights. When the researchers examined census block health data, which cover neighborhoods, they attributed about 15% more deaths to NO2 and PM2.5 than when they used county-level disease data.

The analysis also highlighted racial and ethnic disparities. The study reports that air pollution is linked to one in five childhood asthma cases across the Bay Area but half of cases in West Oakland’s predominantly Hispanic and Black neighborhoods.

“Air pollution impacts communities of color disproportionately,” says Maria Harris, an epidemiologist at the Environmental Defense Fund and one of the study’s authors. The study shows that people in census blocks where residents are predominantly Black, Asian, Hispanic, Pacific Islander, or American Indian are exposed to more air pollution and experience more adverse health effects than people living in predominantly White census blocks.

The studies methods are “immensely valuable for understanding the distribution and impacts of urban air pollution,” says Sally Pusede, an atmospheric chemist who works on local air pollution analysis at the University of Virginia and who was not involved with the work.

Lowering air pollution emissions overall in a city is a social good. But targeting interventions to improve air quality for disproportionately affected communities—by adding green-space buffers between residential and industrial areas, for instance—could help correct “decades of discrimination in housing and planning policies,” Harris says.

Southerland’s group is working to expand this analysis to 13,000 cities around the world using satellite data. Performing continuous mobile air quality monitoring in every major city is not practical—nor is it necessary. The study showed that though satellite data are lower resolution, they can also be used to estimate intracity health impacts. “Satellite data represent an opportunity to get better information about pollution disparities globally,” Southerland says.


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