Long-range fine particulate matter from the 2002 Quebec forest fires and daily mortality in Greater Boston and New York City.

Julie Goodman,Ge Tao,Ke Zu,Christopher Long,Peter Valberg

doi:10.1007/s11869-015-0332-9

Abstract

During July 2002, forest fires in Quebec, Canada, blanketed the US East Coast with a plume of wood smoke. This “natural experiment” exposed large populations in northeastern US cities to significantly elevated concentrations of fine particulate matter (PM2.5), providing a unique opportunity to test the association between daily mortality and ambient PM2.5 levels that are uncorrelated with societal activity rhythms. We obtained PM2.5 measurement data and mortality data for a 4-week period in July 2002 for the Greater Boston metropolitan area (which has a population of over 1.7 million people) and New York City (which has a population of over 8 million people). Daily average PM2.5 concentrations were markedly increased for 3 days over this period, reaching as high as 63 μg/m3 for Greater Boston and 86 μg/m3 for New York City from background ambient levels of 4–48 μg/m3 in the non-smoke days. We examined temporal patterns of natural-cause deaths and 24-h ambient PM2.5 concentrations in July 2002 and did not observe any discernible increase in daily mortality subsequent to the dramatic elevation in ambient PM2.5 levels. Comparison to mortality rates over the same time periods in 2001 and 2003 showed no evidence of impact. Results from Poisson regression analyses suggest that 24-h ambient PM2.5 concentrations were not associated with daily mortality. In conclusion, substantial short-term elevation in PM2.5 concentrations from forest fire smoke were not followed by increased daily mortality in Greater Boston or New York City.Electronic supplementary materialThe online version of this article (doi:10.1007/s11869-015-0332-9) contains supplementary material, which is available to authorized users.

Highlights

A number of single-city and multicity time-series studies have evaluated the association between short-term population exposure to ambient fine particulate matter (PM2.5) and day-byday mortality, many of which have reported small positive risk increments (US EPA 2009)
We examined the association between PM2.5 and mortality in Greater Boston and New York City during and after this natural experiment, wherein substantial short-term increases in PM2.5 levels were uncorrelated with local human activities
The 2002 Quebec wildfires significantly increased airborne PM2.5 in both Greater Boston and New York City over multiple days beginning on Saturday, July 6, and extending into Wednesday, July 10, with the largest PM2.5 impacts occurring on Sunday, July 7

Summary

Introduction

A number of single-city and multicity time-series studies have evaluated the association between short-term population exposure to ambient fine particulate matter (PM2.5) and day-byday mortality, many of which have reported small positive risk increments (US EPA 2009). The National Morbidity, Mortality, and Air Pollution Study (NMMAPS), a large-scale collaborative project that aims to evaluate the health effects of ambient air pollution, conducted a national analysis of PM2.5 and mortality from 1999 to 2000 in 96 US cities and reported that a 10-μg/m3 increase in ambient PM2.5 was associated with a 0.29 % increase (95 % posterior interval 0.01, 0.57) in daily mortality at lag 1 (Dominici et al 2007). Zanobetti and Schwartz (2009) conducted a national analysis of ambient PM2.5-mortality associations from 1999 to 2005 in 112 US cities and reported a pooled estimate of 0.98 % (95 % CI 0.75, 1.22) increase in all-cause daily mortality for a 10-μg/m3 increase in PM2.5 at lag 0–1. Based on the epidemiology evidence, including these studies, the United States Environmental Protection Agency (US EPA) concluded that there is a causal relationship between short-term exposures to PM2.5 and daily mortality (US EPA 2009)

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