Fine Particulate Air Pollution Contributes to Cardiopulmonary Mortality Risk

by | Aug 7, 2019 | 2019, Environmental Health, Lung Cancer, Lung Health

Written by Angeline A. De Leon, Staff Writer. This study observed that in a large, representative, contemporary cohort of U.S. adults, long-term exposure to PM2:5 air pollution was associated with elevated risks of early mortality.

Environmental HealthA large body of research has linked exposure to fine particulate matter (PM, a mixture of hazardous solid and liquid particles less than 2.5 µm in diameter) air pollution to cardiopulmonary disease and lung cancer 1. Generated by the combustion of coal, gasoline, and other biofuels, PM may contain soot, nitrates, and sulfates, hazardous chemicals capable of penetrating the lungs 2. A 2018 meta-analysis by Vodonos and colleagues reported evidence linking long-term exposure to PM with increased risk of mortality in areas of North America, Europe, and Asia 3. However, it is difficult to generalize the impact of PM air pollution to the U.S. adult population, given that many of the cohort studies examining pollution-related effects have been geographically limited 4, over-representative of affluent white adults 5, and/or restricted to specific populations such as postmenopausal women 6, older adults 7, and health professionals 8. Thus, in a research study 9 published in Environmental Health Perspectives (2019), investigators sought to evaluate PM-mortality associations in a large nationally representative cohort of U.S. adults.

Study subjects were individuals aged 18-84 years living in the contiguous U.S. between 1986 and 2014. Subjects participated in the National Health Interview Surveys and were linked to the National Death Index through 2015. A resulting cohort of 1,599,329 U.S. adults was created, as well as a sub-cohort consisting of 635,539 adults with data on smoking and body mass index (BMI). Annual-average PM concentrations were estimated for all cohort members at the census-tract level based on nationwide regulatory monitoring data reports for PM beginning in 1988. Adjusted PM-mortality hazard ratios (HR) were calculated for all-cause and cause-specific deaths, controlling for individual risk factors and regional differences. Additional sensitivity and subgroup analyses were included.

Estimated adjusted mortality HR associated with every 10-µg/m3 increase of long-term PM exposure was 1.13 for all-cause mortality (95% CI: 1.11 to 1.16), 1.24 for cardiopulmonary mortality (95% CI: 1.20 to 1.29), and 1.08 for lung cancer mortality (95% CI: 0.99 to 1.18). Results were similar for the sub-cohort of 635,539 with smoking and BMI profiles: 1.12 for all-cause mortality (95% CI: 1.08 to 1.15), 1.23 for cardiopulmonary mortality (95% CI: 1.17 to 1.29), and 1.12 for lung cancer mortality (95% CI: 1.00 to 1.26). Estimated PM-mortality HRs for all-cause and cardiopulmonary mortality remained similar after controlling for combinations of age, sex, race-ethnicity, and rural vs. urban regions. The PM-mortality association also remained consistently positive across strata for BMI, income, marital status, and survey year. For all-cause mortality, HR was larger for individuals younger than 65 years at the time of survey and never-smokers. The largest PM-mortality HRs were found in the Midwestern regions of the U.S.

Using a large, contemporary cohort of American subjects, the present study’s findings confirm the link between PM air pollution and elevated risk of mortality, all-cause mortality as well as cardiopulmonary mortality and lung cancer mortality. The current investigation benefited from the use of a large, nationally representative sample of U.S. adults, the availability of well-documented air pollution estimates at the census-tract level, and the ability to control for key individual risk factors such as smoking status and BMI in data analysis. Primary limitations include the inability to directly quantify individual lifetime pollution exposure and the observational nature of the study, which prevents the establishment of a direct cause-effect relationship. Overall, however, findings contribute to a better understanding of the impact of air pollution on public health, highlighting the importance of clean breathing air for all populations and socioeconomic groups across the U.S.

Source: Pope CA, Lefler S, Ezzati M, et al. Mortality risk and fine particulate air pollution in a large, representative cohort of U.S. Adults. Environmental Health Perspectives. 2019; 127(7). DOI: 10.1289/EHP4438.

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Posted August 7, 2019.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

References:

  1. Hamra GB, Guha N, Cohen A, et al. Outdoor particulate matter exposure and lung cancer: a systematic review and meta-analysis. Environmental health perspectives. 2014.
  2. Cohen AJ, Brauer M, Burnett R, et al. Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015. The Lancet. 2017;389(10082):1907-1918.
  3. Vodonos A, Awad YA, Schwartz J. The concentration-response between long-term PM2. 5 exposure and mortality; A meta-regression approach. Environmental research. 2018;166:677-689.
  4. Lepeule J, Laden F, Dockery D, Schwartz J. Chronic exposure to fine particles and mortality: an extended follow-up of the Harvard Six Cities study from 1974 to 2009. Environmental health perspectives. 2012;120(7):965-970.
  5. Jerrett M, Turner MC, Beckerman BS, et al. Comparing the health effects of ambient particulate matter estimated using ground-based versus remote sensing exposure estimates. Environmental health perspectives. 2016;125(4):552-559.
  6. Miller KA, Siscovick DS, Sheppard L, et al. Long-term exposure to air pollution and incidence of cardiovascular events in women. New England Journal of Medicine. 2007;356(5):447-458.
  7. Thurston GD, Ahn J, Cromar KR, et al. Ambient particulate matter air pollution exposure and mortality in the NIH-AARP diet and health cohort. Environmental health perspectives. 2015;124(4):484-490.
  8. Hart JE, Liao X, Hong B, et al. The association of long-term exposure to PM 2.5 on all-cause mortality in the Nurses’ Health Study and the impact of measurement-error correction. Environmental Health. 2015;14(1):38.
  9. Pope III CA, Lefler JS, Ezzati M, et al. Mortality Risk and Fine Particulate Air Pollution in a Large, Representative Cohort of US Adults. Environmental health perspectives. 2019;127(7):077007.