Improvements in life expectancy among Americans during the 1980s and 1990s were associated with reductions in fine-particulate air pollution…
Title: Fine-particulate air pollution and life expectancy in the United States
Authors: CA Pope III, M Ezzati, DW Dockery – Reference: N Engl J Med 2009; 360: 376-386,
Reviewer: Robert Goldberg, PhD, Contributing editor, ProCor; Professor of Medicine and Epidemiology, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
Problem addressed: Air pollution in the US and life expectancy.
Purpose of study: To examine the association between changes in fine particulate air pollution during recent decades and life expectancy in Americans residing in major metropolitan areas.
Location of study: United States
Study design: Investigators of these ecologic and cross-sectional analyses utilized data from a variety of sources to examine the a asociation between changes in average life expectancy over the period 1978-1982 and 1997-2001 with declines in fine particulate air pollution among residents of 211 county units in 51 major metropolitan areas throughout the US. To this end, data from the Environmental Protection Agency (EPA) Inhalable Particulate Monitoring Network, other air pollution monitoring sources, and national mortality data were collated and analyzed. Age standardized death rates from lung cancer and chronic obstructive pulmonary disease (COPD) were also utilized as proxy indicators of accumulated exposure to cigarette smoking, which may have acted as an important potential confounder.
Results: In the initial period examined (1978-1982), average life expectancy in the US was 74.3 years whereas average life expectancy increased to 77 years during the most recent period under study of 1997-2001. During the period of improved life expectancy, ambient concentrations of fine particulate matter declined in each of the metropolitan areas examined whereas the death rates from lung cancer and COPD increased.
A variety of cross-sectional and regression analyses were performed to examine the association between changes in the concentrations of air pollutants and increases in life expectancy while controlling for several sociodemographic variables and proxy indicators for cigarette smoking. A decline of 10 ug per cubic meter in the concentration of ambient fine particulate matter was associated with an estimated increase in average life expectancy of slightly more than six months.
Comments: The results of this observational study suggest that improvements in life expectancy among Americans during the 1980s and 1990s were associated with reductions in fine particulate air pollution as measured by various sources in major metropolitan areas throughout the US. While other factors were associated with increases in average life expectancy during the years under study, improvements in air quality were estimated to have contributed to as much as 15% of the overall increase in life expectancy observed.
The results of the present study, which were based on the best data available to the investigators with its inherent strengths and weaknesses, provide encouraging support for the health benefits associated with improvements in air quality noted throughout the US over the past several decades. This has been a direct result of significant discussions and efforts to improve air quality by the EPA and other federal and local agencies.
While there are ongoing concerns with the state of the US economy, and much needed increases in health related sources of funding, the results of the present study suggest that efforts directed at improving the air that we breathe have paid significant dividends with regards to improving life expectancy in Americans. Efforts to improve the quality of the air that Americans (and those of all nations) breathe, and the water they drink, need to be continually encouraged as topics of environmental concern might be placed on the back burner during these difficult economic times. Broad policy level efforts remained needed, as well as efforts that each person can do more of, such as driving their automobiles for fewer miles (with concomitant increases in physical activity), need to be continually encouraged to improve both the general environment as well as our quality and duration of life.