Scientists reported that the United States have made important strides in the global pollution control over the last 36 years, but they have been less successful in addressing disparities of exposure to PM2.5 between communities.
Actually, air pollution rate is unequally distributed across locations overall the world. For example, the average concentration of fine particles (PM2.5 ) has decreased by ~70% since 1981. This improvement in air quality is associated with greater life expectancy, reduced infant mortality, and higher property values.
However, we do not have exact data of how the spatial distribution of PM2.5 has evolved. Particle and other air pollutants represent geographic variation because of the differences in population density, emissions sources, economic activity, climate, and geophysical conditions.
Pollution is also associated with difference in race, poverty, and demographic factors owing socio-political forces and residential states. But the opted policies for the pollution reduction in the U.S from 1981 affected the most this disparity.
Although the U.S. Environmental Protection Agency makes a great effort to guarantee the same degree of protection from environmental hazards for all residents, relative PM2.5
American Scientists provided evidence, in their report in Nature review, on how differences in PM2.5 concentrations between the most and the less polluted areas have declined substantially between 1981 and 2016. However, the most polluted census tracts in 1981 remained the most polluted in 2016 and the least polluted census tracts in 1981 remained the least polluted in 2016.
Also, the most exposed subpopulations in 1981 remained the most exposed in 2016. Overall, absolute disparities have fallen, but relative disparities persist.
These results are obtained from 36 years of PM2.5 concentration measurements over ~8.6 million grid cells with geographic, economic, and demographic data from ~65,000 U.S. census tracts.
They illustrated also that the changes in relative PM2.5 concentrations are not strongly correlated with the socio-economic and the demographic factors. If anything, relative disparities are growing for vulnerable subpopulations. From a socio-economic and demographic perspective, the most exposed subpopulations to fine particles matter remain constant over time, according to the report.