Low-Concentration PM2.5 and Mortality

Research studies on wood smoke and other air pollution.

Low-Concentration PM2.5 and Mortality

Postby Wilberforce » Sat Jun 06, 2015 7:25 pm

Low-Concentration PM2.5 and Mortality: Estimating Acute and Chronic Effects in a Population-Based Study
Shi et al
Background: Both short- and long-term exposures to fine particulate matter (PM2.5) are associated with mortality. However, whether the associations exist below the new EPA standards (12 µg/m3 of annual average PM2.5, 35 µg/m3 daily) is unclear. In addition, it is not clear whether results of previous time series studies (fit in larger cities) and cohort studies (fit in convenience samples) are generalizable to the general population.

Objectives: To estimate the effects of low-concentration PM2.5 on mortality.

Methods: High resolution (1 × 1 km) daily PM2.5 predictions, derived from satellite aerosol optical depth retrievals, were employed. Poisson regressions were applied to the Medicare population (age>=65) in New England to simultaneously estimate the acute and chronic effects, with mutual adjustment for short- and long-term exposure, as well as area-based confounders. Models were also restricted to annual concentrations below 10 µg/m3 or daily concentrations below 30 µg/m3.

Results: PM2.5 was associated with increased mortality. In the cohort, 2.14% (95% CI: 1.38, 2.89%) and 7.52% (95% CI: 1.95, 13.40%) increases were estimated for each 10 µg/m3 increase in short- (2 day) and long-term (1 year) exposures, respectively. The associations still held for analyses restricted to low-concentration PM2.5 exposures. The corresponding estimates were 2.14% (95% CI: 1.34, 2.95%) and 9.28% (95% CI: 0.76, 18.52%). Penalized spline models of long-term exposure indicated a higher slope for mortality in association with exposures above versus below 6 µg/m3. In contrast, the association between short-term exposure and mortality appeared to be linear across the entire exposure distribution.

Conclusions: Using a mutually adjusted model, we estimated significant acute and chronic effects of PM2.5 exposures below current EPA standards. These findings suggest that improving air quality below current standards may benefit public health.
• The Surgeon General has determined that there is no safe level of exposure to ambient smoke!

• If you smell even a subtle odor of smoke, you are being exposed to poisonous and carcinogenic chemical compounds!

• Even a brief exposure to smoke raises blood pressure, (no matter what your state of health) and can cause blood clotting, stroke, or heart attack in vulnerable people. Even children experience elevated blood pressure when exposed to smoke!

• Since smoke drastically weakens the lungs' immune system, avoiding smoke is one of the best ways to prevent colds, flu, bronchitis, or risk of an even more serious respiratory illness, such as pneumonia or tuberculosis! Does your child have the flu? Chances are they have been exposed to ambient smoke!
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