TITLE:
Short-Term Effects of Ozone and PM2.5 on Mortality in 12 Canadian Cities
AUTHORS:
Nawal Farhat, Tim Ramsay, Michael Jerrett, Daniel Krewski
KEYWORDS:
Air Pollution; Ozone; Particulate Matter; Mortality; Canada
JOURNAL NAME:
Journal of Environmental Protection,
Vol.4 No.12A,
December
18,
2013
ABSTRACT:
Numerous recent epidemiological studies
have linked health effects with short-term exposure to air pollution levels commonly
found in North America. The association between two key pollutants—ozone and fine
particulate matter— and
mortality in 12 Canadian cities was explored in a time-series study. City-specific
estimates were obtained using Poisson regression models, adjusting for the effects
of seasonality and temperature. Estimates were then pooled across cities using the
inverse variance method. For a 10 ppb increase in 1-hr daily maximum ozone levels,
significant associations were in the range of 0.56% - 2.47% increase in mortality. For a 10 μg/m3 increase in the 24-hr average PM2.5 concentration of, significant associations
varied between 0.91% and 3.17% increase in mortality. Generally, stronger associations
were found among the elderly. Effects estimates were robust to adjustment for seasonality,
but were sensitive to lag structures. There was no evidence for effect modification
of the mortality-exposure association by city-level ecologic covariates.