US air pollution rates falling, but pockets of inequity remain: study

Over the past decades, air pollution emissions have decreased significantly; However, the magnitude of the change varies by demographics, according to a new study from Columbia University’s Mailman School of Public Health. The results indicate that racial/ethnic and socioeconomic disparities exist in reductions in air pollution emissions, particularly in the industrial and energy production sectors. The results are published in the journal Natural communications.

The research provides a national survey of changes in air pollution emissions over the 40 years since the Clean Air Act (CAA) was enacted. Studies to date have primarily focused on assessing disparities in air pollution simultaneously, focusing on pollutant concentrations rather than emissions.

However, the focus on emissions has more direct implications for regulations and policies. In this study, researchers used county-level data to assess racial/ethnic and socioeconomic disparities in changes in air pollution emissions in the neighboring United States between 1970 and 2010.

“The analyzes provide insight into the sociodemographic characteristics of counties that have experienced disproportionate decreases in air pollution emissions over the past 40 years,” said Yanelli Nunez, Ph.D., first author of the study and department scientist. . in Environmental Health Sciences at the Columbia Mailman School of Public Health and affiliated with PSE Healthy Energy.

By analyzing air pollution emissions, researchers have identified specific pollution source sectors that are potentially important contributors to disparities in air pollution exposure.

Nunez and colleagues leveraged air pollution emissions data from the Global Burden of Disease Inventory of Major Sources of Air Pollution to analyze air pollutant emissions from six pollution-producing sectors: industry (carbon dioxide sulfur), energy (sulfur dioxide and nitrogen oxides), agriculture (ammonia), road transport (nitrogen oxides), commercial (nitrogen oxides) and residential (organic carbon particles).

On average, air pollution emissions in the United States declined significantly between 1970 and 2010 in all source sectors considered by the researchers, except ammonia emissions from agriculture and particulate matter emissions. of organic carbon from the residential sector, which researchers say comes mainly from the use of solid biofuels for indoor heating. .

The most pronounced emissions decreases were observed for sulfur dioxide from industrial and energy production activities. Nitrogen oxide emissions from transportation, commercial activities and energy production have declined moderately.

Despite overall downward trends for most pollutants, the researchers found that some populations experienced relatively smaller reductions, or even increases, in air pollution emissions.

For example, an increase in a county’s average percentage of Hispanic or Native American population resulted in a relative increase in emissions of sulfur dioxide, nitrogen oxides, and ammonia from the industrial, energy production and agriculture.

Additionally, an increase in county median family income was linked to increased emissions reductions in every pollution-source sector the researchers analyzed, except agriculture.

“Air pollution emissions do not perfectly capture population exposure to air pollution, and we also know that neighborhood-level air pollution inequalities are common, which we could not analyzed in this study given the available data,” noted Marianthi-Anna Kioumourtzoglou, ScD, associate professor of environmental health sciences at the Columbia Mailman School and lead author.

“In this study, we provide information on potential racial/ethnic and socioeconomic inequalities in nationwide air pollution reductions from major sources of air pollution, which can inform regulators and complement the analysis at the local level.”

“Policies specifically targeting reductions in overburdened populations could support more equitable reductions in air pollution and reduce disparities in air pollution exposure,” observed Dr. Nunez. “This is an important lesson learned from 53 years of implementation of the Clean Air Act, which is particularly relevant as we develop policies to transition to renewable energy sources, which will have a collateral impact on air quality and, consequently, on public health. “