TLDR
Forest-fire haze in the Klang Valley was linked to more deaths from breathing-related illnesses, both on haze days and several days afterward. Men, especially older men, showed particularly large increases.
Summary
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1 Study Aim
The authors aimed to assess whether forest-fire haze events were linked to daily deaths in Malaysia’s Klang Valley from 2000 to 2007. The study asked whether hazy days were followed by more deaths.
2 Study Design
The study used a case-crossover design (comparing exposure shortly before an event with exposure on other days for the same population). The authors analyzed daily mortality and air-pollution data in the Klang Valley from 2000 to 2007. They classified haze days as days when PM10 (particulate matter, or airborne particles, no larger than 10 micrometers) exceeded 100 micrograms per cubic meter. The study identified 88 haze days and examined natural and respiratory deaths, including differences by sex and age. The researchers compared deaths around smoky days with deaths on other days.
3 Findings
The authors report that haze exposure was associated with immediate and delayed mortality effects. On haze days, respiratory deaths increased by 19% overall, 34% among males, and 41% among elderly males. The highest mortality associations were reported two to five days after exposure. These findings suggest that health risks may continue after haze clears, supporting attention to vulnerable groups during and after haze events. More people died from breathing-related illnesses on smoky days and in the days that followed, especially older men.