1. Investigation of association between smoke haze and under-five mortality in Malaysia, accounting for time lag, duration and intensity
- Author
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Vera Ling Hui Phung, Wan Rozita Wan Mahiyuddin, Akiko Honda, Mazrura Sahani, Kayo Ueda, Hirohisa Takano, and Xerxes Seposo
- Subjects
medicine.medical_specialty ,Haze ,010504 meteorology & atmospheric sciences ,Epidemiology ,Lag ,corneal opacity ,Time lag ,Accounting ,010501 environmental sciences ,children’s health ,01 natural sciences ,fire-physical phenomenon ,Air Pollution ,Smoke ,Humans ,Medicine ,Mortality ,Child ,0105 earth and related environmental sciences ,Air Pollutants ,Cross-Over Studies ,business.industry ,fire-disasters ,Malaysia ,General Medicine ,Odds ratio ,Fire ,Southeast Asia ,eye diseases ,Confidence interval ,haze ,asia, southeastern ,Intensity (physics) ,Particulate Matter ,business - Abstract
Background Studies on the association between smoke haze (hereafter ‘haze’) and adverse health effects have increased in recent years due to extreme weather conditions and the increased occurrence of vegetation fires. The possible adverse health effects on under-five children (U5Y) is especially worrying due to their vulnerable condition. Despite continuous repetition of serious haze occurrence in Southeast Asia, epidemiological studies in this region remained scarce. Furthermore, no study had examined the association accounting for three important aspects (time lag, duration and intensity) concurrently. Objective This study aimed to examine the association between haze and U5Y mortality in Malaysia, considering time lag, duration and intensity of exposure. Methods We performed a time-stratified case-crossover study using a generalized additive model to examine the U5Y mortality related to haze in 12 districts in Malaysia, spanning from 2014 to 2016. A ‘haze day’ was characterized by intensity [based on concentrations of particulate matter (PM)] and duration (continuity of haze occurrence, up to 3 days). Results We observed the highest but non-significant odds ratios (ORs) of U5Y mortality at lag 4 of Intensity-3. Lag patterns revealed the possibility of higher acuteness at prolonged and intensified haze. Stratifying the districts by the 95th-percentile of PM distribution, the ‘low’ category demonstrated marginal positive association at Intensity-2 Duration-3 [OR: 1.210 (95% confidence interval: 1.000, 1.464)]. Conclusions We found a null association between haze and U5Y mortality. The different lag patterns of the association observed over different duration and intensity suggest consideration of these aspects in future studies.
- Published
- 2021
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