Studies show that pollution, whether from factories or traffic-snarled roads, disproportionately affects communities where people of different races live. Scientists have begun documenting the differences in detail, but they don't have enough information on daily variations. Scientists are looking at how exposure varies from day to day in 11 major US cities. Climate change could make the differences worse.
At the fall meeting of the American Chemical Society, the researchers will present their findings.
Dropping off a few hundred yards from a freeway is one way air pollution levels can vary. Sally Pusede is one of the researchers who have used satellite and other observations to determine how air quality varies at the level of neighborhoods.
This approach doesn't take into account another important variable. "When we regulate air pollution, we don't think of it as being unchanging over time, we think of it as dynamic," says Pusede. She says that the new work takes a step forward by looking at how these levels vary.
Information about the fluctuations can help find the source of pollution. Pusede and colleagues at the University of Virginia found that air quality in major U.S. cities improved on weekends. The drop was tied to the reduction of diesel- fueled trucks. More than half of these trucks are parked on Saturdays and Sundays.
The gas NO 2 is a component of the complex brew of potentially harmful compounds. Scientists look to NO 2 for a sense of air pollution levels. Exposure to high concentrations of this gas can cause lung problems. Asthma can be caused by elevated levels of NO 2 over time.
The team has been using data on NO 2 collected almost daily by a space-based instrument known as TRO POMI, which they confirmed with higher resolution measurements made from a similar sensor on an airplane flown as part of NASA's LISTOS project. The census tracts are defined by the U.S. Census Bureau. In a proof-of-concept project, they used this approach to analyze initial differences in Houston, and then used these data-gathering methods to study daily differences in New York City and Newark, New Jersey.
Satellite-based data for 11 additional cities has been analyzed for daily variations. Atlanta, Baltimore, Chicago, Denver, Houston, Kansas City, Los Angeles, Phoenix, Seattle, St. Louis, and Washington, D.C. are all in the same city. On some days, the levels of pollution were much higher than on other days. Washington, D.C. had the lowest disparity, with an average of 10% higher levels in black, Hispanic and Asian communities.
As in New York City and Newark, the researchers looked at the data to see if there were any links with wind and heat. Although the analysis is not complete, the team has found a direct correlation between stagnant air and pollution distribution, which was not surprising because of the wind. Air pollution is expected to increase in the northeastern and southwestern U.S. if action is not taken to reduce emissions. The team did not find a strong connection with heat. Climate change is predicted to increase the number of hot days. According to the researchers, if greenhouse gas emissions aren't reduced soon, people in these communities could face more days in which conditions are hazardous to their health.
Pusede would like to see this type of analysis used to support the fight for air quality. She says that it's possible to evaluate the success of interventions, such as rerouting diesel trucks or adding emissions controls, to reduce them.
More information: Observing air pollution inequality from space, ACS Fall 2022, www.acs.org/content/acs/en/mee … tings/fall-2022.html
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