Most polluted neighborhoods in US with worst air quality remain unchanged after 3 decades: Study

While the level of fine particulate air pollution has declined considerably over the last several decades, researchers found that its distribution has remained largely unchanged


                            Most polluted neighborhoods in US with worst air quality remain unchanged after 3 decades: Study
(Getty Images)

While air pollution has declined considerably over the last several decades in the US, there are significant disparities as to who breathes the worst air. Even after over three decades, the most polluted areas in the US continue to remain the most polluted today, according to researchers from the University of Virginia, Stanford University, and the US Census Bureau. In contrast, areas that were less polluted in 1981 were still less polluted in 2016. However, areas that “were Whiter and richer in 1981” have become relatively less polluted over time. Further, areas that “became Whiter and richer between 1981 and 2016” have become relatively less polluted over time. 

The level of fine particulate air pollution has declined substantially in the US. Overall, the concentration of fine particulate air pollution (PM2.5) — airborne particulate matter less than 2.5 microns in diameter — has decreased by roughly 70% since 1981 in the US. While this has led to improvements in air quality and by extension, human health and economic well-being, the authors found that its distribution has remained largely unchanged. 

According to the experts, like other types of pollution and environmental hazards, increased levels of air pollution are often associated with disparities between different racial, ethnic and economic groups. However, little is known about how the spatial distribution of PM2.5 has evolved over time. The team, therefore, combined measurements of PM2.5 spanning 1981-2016 with geographic, economic, and demographic data from 65,000 neighborhoods across the US. They used PM2.5 data observed at 8.6 million distinct locations over 36 years. “We do not attempt a formal welfare analysis. Nevertheless, environmental justice and reducing disparities have been stated as objectives of the US environmental policy for decades. US Environmental Protection Agency and state guidelines aim for all people to enjoy the same degree of protection from environmental hazards and stipulate that no groups should bear a disproportionate share of pollution,” emphasizes the team in the study published in Science. 

Like other types of pollution and environmental hazards, increased levels of air pollution are often associated with disparities between different racial, ethnic, and economic groups, say experts.
(Getty Images)

The results reveal that the most and least polluted US neighborhoods in 1981 remained the most and least polluted more than 30 years later, with disadvantaged communities with more Black or Hispanic people far more likely to have higher levels of particulate pollution at any given time. The findings reveal persistent socioeconomic disparities in access to clean air and highlight the perpetual problem of environmental inequality, say experts. “We show that differences in PM2.5 between more and less polluted areas declined substantially between 1981 and 2016. However, the most polluted census tracts in 1981 remained the most polluted in 2016. The least polluted census tracts in 1981 remained the least polluted in 2016. The most exposed subpopulations in 1981 remained the most exposed in 2016. Overall, absolute disparities have fallen, but relative disparities persist,” say researchers.

However, some local variation exists. Ohio, West Virginia, eastern Kentucky, and the Northeast Corridor became relatively less polluted. California’s Central and Imperial Valleys, southwestern Arizona, southern Texas, and western Arkansas and eastern Oklahoma became relatively more polluted. “Mechanisms for differential trends in these specific locations may include import competition, the decline in manufacturing, changes in the structure of energy production (for example, the hydraulic fracking boom, a decline in coal production), and differential environmental regulation,” explain authors. 

In a related perspective, an expert from the University of Kentucky writes that further investigation to determine what caused the downward shift in the pollution distribution and the preservation of rankings over time could inform policies that “avoid undesirable distributional consequences.” “Implementing environmental justice is, therefore, ultimately inseparable from assessing the mechanisms that created the inequities in the first place,” says the perspective. 

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