Biomass smoke pollution and mortality rates in Launceston, Australia, 1994-2007: evaluation of coordinated interventions to improve ambient air quality

Abstract

BACKGROUND In Launceston, Tasmania, coordinated interventions to reduce pollution from domestic wood heaters were implemented from 2001. These were associated with substantially improved winter air quality. The interventions included community education, enforcement of environmental regulations, and a wood heater replacement program. AIM To assess the effect of reductions in biomass smoke pollution on daily mortality. METHODS We assessed changes in daily all-cause, cardiovascular and respiratory mortality during the 6.5 year periods before and after June 2001 in Launceston and in Hobart, a comparable city that did not receive any air quality interventions. Age-stratified time-series analysis of daily mortality using Poisson regression models adjusted for the effects of temperature, humidity, day of week, respiratory epidemics, and secular mortality trends, were applied to Launceston and Hobart. RESULTS Mean daily wintertime PM10 fell from 42 µg/m3 during 1994-2000 to 26 µg/m3 during 2001-2007 in Launceston. The period of improved air quality was associated with small non-significant reductions in annual mortality. In males the observed reductions in annual mortality were of greater magnitude and statistically significant for all-cause (-11.4%, 95%CI -19.2 to -2.9 p=0.01), cardiovascular (-17.9%, 95% CI -30.6 to -2.8 p=0.02) and respiratory (-22.8%, 95% CI -40.6 to 0.3 p=0.05) mortality. In wintertime statistically borderline reductions in cardiovascular (-19.6%, 95%CI -36.3 to 1.5 p=0.06) and respiratory (-27.9% 95%CI -49.5 to 3.1 p=0.07) mortality were observed (males and females combined). There were no significant mortality changes in the non-intervention city of Hobart CONCLUSIONS Decreased air pollution from ambient biomass smoke was associated with reduced annual mortality in males, and with reduced cardiovascular and respiratory mortality during winter months.