Tuesday, January 26, 2016

What are the Health Impacts of Low Concentrations of PM2.5?

Low-Concentration PM2.5 and Mortality: Estimating Acute and Chronic Effects in a Population-Based Study (7 page pdf, Liuhua Shi, Antonella Zanobetti, Itai Kloog, Brent A. Coull, Petros Koutrakis, Steven J. Melly, and Joel D. Schwart, Environmental Health Perspectives, Jan. 1, 2016)

 Today we review research into the mortality impact, resulting from exposures to low concentrations of PM2.5 on both the short and long term, among a large population cohort in New England over the age of 65. The question is whether concentrations below EPA standards (12 μg/m3 of annual average PM2.5, 35 μg/m3 daily) still present a risk of death. Results indicate that low concentrations present a risk that varies according to the sources and composition of the particles with may include secondary aerosols. A major conclusion with public health policy implications was that improving air quality even at low levels of PM2.5 can yield health benefits.

  low levels pm

 Key Quotes:

“Both short- and long-term exposures to fine particulate matter (≤ 2.5 μm; PM2.5) are associated with mortality. However, whether the associations exist at levels below the new U.S. Environmental Protection Agency (EPA) standards (12 μg/m3 of annual average PM2.5, 35 μg/m3 daily) is unclear”

“there is spatial variability in PM2.5 concentrations within cities that time series studies generally do not take into account, which can introduce exposure measurement error.. In general, existing study cohorts are not representative of the overall population.”

“the estimated percent change in all-cause mortality with 95% CIs for a 10-μg/m3 increase in both short- and long term PM2.5 in the restricted and full cohort. In the restricted population, we found an estimated 9.28% increase in mortality (95% CI: 0.76, 18.52%) for every 10-μg/m3 increase in long-term PM2.5 exposure. A 2.14% increase in mortality (95% CI: 1.34, 2.95%) was observed for every 10-μg/m3 increase in short term PM2.5 exposure.”

 “When we applied the predicted daily PM2.5 with 1-km spatial resolution from our novel hybrid models, we observed that both short- and long-term PM2.5 exposure were significantly associated with all-cause mortality among residents of New England ≥ 65 years of age,”

 “Our findings suggest a larger effect at low concentrations among those ≥ 65 years of age, which may also reflect particle composition. The sources and composition of the particles may differ between low-pollution days and high-pollution days, which are likely more affected by secondary aerosols.”

“Our findings show that both short- and long-term exposure to PM2.5 were associated with all-cause mortality, even for exposure levels not exceeding the newly revised U.S. EPA standards, suggesting that adverse health effects occur at low levels of fine particles.”

“improving the air quality at even lower levels of PM2.5 than presently allowed by the U.S. EPA standards can yield health benefits.”

No comments:

Post a Comment