Health risks of air pollution on mortality in Klang Valley, Malaysia

Abstract

Background/Aims: In the first coordinated Public Health and Air Pollution in Asia (PAPA) study, the results showed that short-term exposures to polluted air were associated with daily mortality rates in some major cities in Asia. However, there are limited numbers of health effects of air pollution studies in Malaysia due to lack of capacity in environmental epidemiology. In this study, we conducted the first daily air pollution time series study in Klang Valley which is a heavily industrialized urban area in Malaysia, using a protocol developed by the PAPA study.

Objective: To estimate the health risks of 5 criteria air pollutants on mortality in Klang Valley.

Methods: Daily deaths records for Klang Valley from 2000 to 2006 were obtained from the Statistics Department. For the same period, daily concentrations of the criteria air pollutants (PM10, SO2, NO2, O3, and CO) and the daily meteorological data (temperature, relative humidity, and rainfall) were obtained from the Department of Environment and the Meteorological Service Department, respectively. Descriptive analysis was performed to identify the trend for the air pollutants and the mortality data. We used Poisson regression to model the daily mortality counts while controlling for time trends, temperature, rainfall, month and day of the week, and assessed effects of single pollutant and multiple pollutants.

Results: The main air pollutants in the Klang Valley region were ozone and PM10. In the single pollutant model, the RRs of all pollutants were found to be greater than 1.0 except for NO2 and SO2 at lag 0 and lag 1, respectively. However, these RR were insignificant. The natural-cause mortality risk was significant for PM10 at lag 1 and ozone at lag 2 and at average lag 0 to lag 2 concentrations. In the multiple pollutant models, the highest excess risk was found for ozone at lag 2 with 1.10% per 10 µg/m3 increase in ozone. The risks on respiratory and cardiovascular mortality were also found.

Conclusion: The study confirms the association between mortality risks and air pollutants, particularly for ozone and PM10, as with magnitude similar to those by other studies worldwide.