A case-crossover analysis of forest fire haze events and mortality in Malaysia

Mazrura Sahani, Nurul Ashikin Zainon, Wan Rozita Wan Mahiyuddin, Mohd Talib Latif, Rozita Hod, Firoz Khan, Norhayati Mohd Tahir, Chang Chuan Chan

Research output: Contribution to journalArticle

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Abstract

The Southeast Asian (SEA) haze events due to forest fires are recurrent and affect Malaysia, particularly the Klang Valley region. The aim of this study is to examine the risk of haze days due to biomass burning in Southeast Asia on daily mortality in the Klang Valley region between 2000 and 2007. We used a case-crossover study design to model the effect of haze based on PM10 concentration to the daily mortality. The time-stratified control sampling approach was used, adjusted for particulate matter (PM10) concentrations, time trends and meteorological influences. Based on time series analysis of PM10 and backward trajectory analysis, haze days were defined when daily PM10 concentration exceeded 100μg/m3. The results showed a total of 88 haze days were identified in the Klang Valley region during the study period. A total of 126,822 cases of death were recorded for natural mortality where respiratory mortality represented 8.56% (N=10,854). Haze events were found to be significantly associated with natural and respiratory mortality at various lags. For natural mortality, haze events at lagged 2 showed significant association with children less than 14 years old (Odd Ratio (OR)=1.41; 95% Confidence Interval (CI)=1.01-1.99). Respiratory mortality was significantly associated with haze events for all ages at lagged 0 (OR=1.19; 95% CI=1.02-1.40). Age-and-gender-specific analysis showed an incremental risk of respiratory mortality among all males and elderly males above 60 years old at lagged 0 (OR=1.34; 95% CI=1.09-1.64 and OR=1.41; 95% CI=1.09-1.84 respectively). Adult females aged 15-59 years old were found to be at highest risk of respiratory mortality at lagged 5 (OR=1.66; 95% CI=1.03-1.99). This study clearly indicates that exposure to haze events showed immediate and delayed effects on mortality.

Original languageEnglish
Pages (from-to)257-265
Number of pages9
JournalAtmospheric Environment
Volume96
DOIs
Publication statusPublished - 2014

Fingerprint

haze
forest fire
mortality
confidence interval
valley
analysis
time series analysis
biomass burning
particulate matter
gender
trajectory

Keywords

  • Air pollution
  • Case-crossover
  • Haze
  • Malaysia
  • Mortality

ASJC Scopus subject areas

  • Atmospheric Science
  • Environmental Science(all)

Cite this

A case-crossover analysis of forest fire haze events and mortality in Malaysia. / Sahani, Mazrura; Zainon, Nurul Ashikin; Wan Mahiyuddin, Wan Rozita; Latif, Mohd Talib; Hod, Rozita; Khan, Firoz; Tahir, Norhayati Mohd; Chan, Chang Chuan.

In: Atmospheric Environment, Vol. 96, 2014, p. 257-265.

Research output: Contribution to journalArticle

Sahani, Mazrura ; Zainon, Nurul Ashikin ; Wan Mahiyuddin, Wan Rozita ; Latif, Mohd Talib ; Hod, Rozita ; Khan, Firoz ; Tahir, Norhayati Mohd ; Chan, Chang Chuan. / A case-crossover analysis of forest fire haze events and mortality in Malaysia. In: Atmospheric Environment. 2014 ; Vol. 96. pp. 257-265.
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AB - The Southeast Asian (SEA) haze events due to forest fires are recurrent and affect Malaysia, particularly the Klang Valley region. The aim of this study is to examine the risk of haze days due to biomass burning in Southeast Asia on daily mortality in the Klang Valley region between 2000 and 2007. We used a case-crossover study design to model the effect of haze based on PM10 concentration to the daily mortality. The time-stratified control sampling approach was used, adjusted for particulate matter (PM10) concentrations, time trends and meteorological influences. Based on time series analysis of PM10 and backward trajectory analysis, haze days were defined when daily PM10 concentration exceeded 100μg/m3. The results showed a total of 88 haze days were identified in the Klang Valley region during the study period. A total of 126,822 cases of death were recorded for natural mortality where respiratory mortality represented 8.56% (N=10,854). Haze events were found to be significantly associated with natural and respiratory mortality at various lags. For natural mortality, haze events at lagged 2 showed significant association with children less than 14 years old (Odd Ratio (OR)=1.41; 95% Confidence Interval (CI)=1.01-1.99). Respiratory mortality was significantly associated with haze events for all ages at lagged 0 (OR=1.19; 95% CI=1.02-1.40). Age-and-gender-specific analysis showed an incremental risk of respiratory mortality among all males and elderly males above 60 years old at lagged 0 (OR=1.34; 95% CI=1.09-1.64 and OR=1.41; 95% CI=1.09-1.84 respectively). Adult females aged 15-59 years old were found to be at highest risk of respiratory mortality at lagged 5 (OR=1.66; 95% CI=1.03-1.99). This study clearly indicates that exposure to haze events showed immediate and delayed effects on mortality.

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