Particulate air pollution (haze) due to the 1997 forest fires and effects on deaths in Malaysia

Abstract

In 1997, uncontrolled widespread forest fires resulted in severe haze or smoke pollution in Malaysia. We aimed to determine associations between particulate air pollution and daily mortality in three cities during the haze period. We analysed daily hospital-based mortality data and air pollution data using Poisson regression methods. Mean daily particulate matter less than 10 microns (PM₁₀) levels reached 458μglm3, 852μg/m3, and 148μg/m³ in Kuala Lumpur, Kuching and Kota Bharu respectively. There were no significant associations between the haze period and non-trauma mortality for the three cities. In Kuala Lumpur there were associations between mean daily PM 10 and non-trauma deaths (RR= 1.04, 95%CI = 0.90- 1.21) and cardiovascular deaths (RR = 1.24, 95%CI = 0.96-1.60), and between carbon monoxide and cardiovascular deaths (RR = 1.18, 95%CI = 0.94-1.46). In both Kuching and Kota Bharu, there were no significant associations between air pollutants and deaths except for between carbon monoxide and cardiovascular deaths in Kota Bharu (RR = 1.57, 95%CI = 1.06- 2.32). In Kuala Lumpur we found only a weak, non-significant association between daily PM₁₀ levels and deaths. Although we did not find any associations between the peak haze period and mortality in any of the three cities, a real effect may have been obscured by methodological and data constraints. The findings have important implications for governments in terms of risk management and risk communication when particulate air pollution is due to forest fires or bush fires.