From the University of North Carolina, Gillings School of Global Public Health. This should limit the urgency that the EPA had over implementing new air pollution laws where they make claims of increasing death tolls.
Air pollution in the U.S. has decreased since about 1990, and a new study conducted at the University of North Carolina at Chapel Hill now shows that this air quality improvement has brought substantial public health benefits. The study, published Oct 19 in the journal Atmospheric Chemistry and Physics, found that deaths related to air pollution were nearly halved between 1990 and 2010.
The team’s analyses showed that deaths related to air pollution exposure in the U.S. decreased by about 47 percent, dropping from about 135,000 deaths in 1990 to 71,000 in 2010.
These improvements in air quality and public health in the U.S. coincided with increased federal air quality regulations, and have taken place despite increases in population, energy and electricity use, and vehicle miles traveled between 1990 and 2010.
“We’ve invested a lot of resources as a society to clean up our air,” said Jason West, PhD, professor of environmental sciences and engineering at the UNC Gillings School of Global Public Health and study co-author. “This study demonstrates that those changes have had a real impact with fewer people dying each year due to exposure to outdoor air pollution.”
The study was led by Yuqiang Zhang, PhD, former postdoctoral researcher at the UNC Gillings School and at the Environmental Protection Agency and current research scientist at the Duke University Nicholas School of the Environment, and in collaboration with West and several scientists at the EPA.
This study supports results from a small number of other recent studies that also showed similar and marked reductions in air pollution-related deaths, but this study is unique in its use of a 21-year computer simulation and ability to estimate air pollution deaths each year.
Zhang, West and colleagues analyzed concentrations of two pollutants, known as PM2.5 and ozone, from a 21-year computer simulation of air pollution across the U.S. PM2.5 are very small particles suspended in the air that come from power plants, motor vehicles, industries, and some commercial and residential sources. The diameter of such small particles is less than 2.5 micrometers, which is about 3 percent of the diameter of a human hair.
They then related the declining concentrations of PM2.5 and ozone to the geographical areas in which people live and the causes of death in those areas, using data from the Centers for Disease Control and Prevention, to estimate deaths from air pollution during the period. They estimated deaths from ischemic heart disease, chronic obstructive pulmonary disease, lung cancer and stroke related to PM2.5, and from respiratory disease for ozone.
Because other factors also influence the overall rates of these causes of death, the drop in deaths was not solely the result of improved air quality. Still, the authors found that improved air quality likely reduced deaths by about 40,000 in 2010, compared to the number that would have resulted if air pollution had stayed the same from 1990 to 2010.
“These health improvements likely have continued beyond 2010 as we observe that air pollutant concentrations have continued to decrease,” said Zhang.
The team plans to use other datasets to analyze air pollution deaths since 2010.
Still, despite clear improvements, air pollution remains an important public health issue in the U.S. The estimated 71,000 deaths in 2010 translates to 1 of every 35 deaths in the U.S. – that’s as many deaths as we see from all traffic accidents and all gun shootings combined.
“Even though we’ve seen some tangible success, there are still people dying, and a public health challenge remains going forward,” West said. “New federal policies curtailing air pollution regulations likely will slow the improvement in air quality or possibly make air quality worse.”
The study was funded by NASA through its Health and Air Quality Applied Sciences Team, of which Dr. West is a member, and by the EPA.
The paper: (open access) https://www.atmos-chem-phys.net/18/15003/2018/
Long-term trends in the ambient PM2.5– and O3-related mortality burdens in the United States under emission reductions from 1990 to 2010
Abstract. Concentrations of both fine particulate matter (PM2.5) and ozone (O3) in the United States (US) have decreased significantly since 1990, mainly because of air quality regulations. Exposure to these air pollutants is associated with premature death. Here we quantify the annual mortality burdens from PM2.5 and O3 in the US from 1990 to 2010, estimate trends and inter-annual variability, and evaluate the contributions to those trends from changes in pollutant concentrations, population, and baseline mortality rates. We use a fine-resolution (36km) self-consistent 21-year simulation of air pollutant concentrations in the US from 1990 to 2010, a health impact function, and annual county-level population and baseline mortality rate estimates. From 1990 to 2010, the modeled population-weighted annual PM2.5 decreased by 39%, and summertime (April to September) 1h average daily maximum O3 decreased by 9% from 1990 to 2010. The PM2.5-related mortality burden from ischemic heart disease, chronic obstructive pulmonary disease, lung cancer, and stroke steadily decreased by 54% from 123700deathsyear−1 (95% confidence interval, 70800–178100) in 1990 to 58600deathsyear−1 (24900–98500) in 2010. The PM2.5-related mortality burden would have decreased by only 24% from 1990 to 2010 if the PM2.5 concentrations had stayed at the 1990 level, due to decreases in baseline mortality rates for major diseases affected by PM2.5. The mortality burden associated with O3 from chronic respiratory disease increased by 13% from 10900deathsyear−1 (3700–17500) in 1990 to 12300deathsyear−1 (4100–19800) in 2010, mainly caused by increases in the baseline mortality rates and population, despite decreases in O3 concentration. The O3-related mortality burden would have increased by 55% from 1990 to 2010 if the O3 concentrations had stayed at the 1990 level. The detrended annual O3 mortality burden has larger inter-annual variability (coefficient of variation of 12%) than the PM2.5-related burden (4%), mainly from the inter-annual variation of O3 concentration. We conclude that air quality improvements have significantly decreased the mortality burden, avoiding roughly 35800 (38%) PM2.5-related deaths and 4600 (27%) O3-related deaths in 2010, compared to the case if air quality had stayed at 1990 levels (at 2010 baseline mortality rates and population).