by Chee-khoon Chan
23rd June 2013

In 2002, Narayan Sastry, currently a professor of demography at the University of Michigan published a paper entitled “Forest Fires, Air Pollution, and Mortality in Southeast Asia” in the February 2002 issue of the journal Demography.

The smog of 1997 coincided with an El Niño year which intensified the seasonal mid-year drought. The land clearing and forest fires in that year burned an estimated 2-3% of Indonesian land area, mostly in Sumatra and Kalimantan but also affecting sizeable tracts in Irian Jaya, Sulawesi, Java, Sumbawa, Komodo, Flores, Sumba, Timor, Wetar as well as areas in Sarawak and Brunei.

Sastry obtained daily mortality statistics from the Department of Statistics in Malaysia and correlated these with the daily Air Pollution Index (API) readings from the Malaysian Meteorological Department, in order to analyze the acute mortality in Kuching and Kuala Lumpur following upon days of high air pollution (defined as days when PM10 > 210 ug/m3). (The API is largely based on PM10, the concentration of suspended particulates of size 10 microns and below).

For a fifteen-day period in September 1997, the API in Kuching reached or exceeded 850. The highest API reading recorded was 930, and visibility was down to about 10 metres. In Peninsular Malaysia, API readings hovered in the 200-300 range during the same period. One shudders to imagine what the situation would have been like in the affected areas closer to the hot spots.

The salient findings were reported thus in Demography:

“a high air pollution day associated with the smoke haze increased the total all-cause mortality by roughly 20%. Higher mortality was apparent in two locations – Kuala Lumpur and Kuching (Sarawak ) – and affected mostly the elderly. In Kuala Lumpur, non-traumatic mortality among the population aged 65-74 increased about 70% following a day of high levels of air pollution. This effect was persistent; it was not simply a moving forward of deaths by a couple of days (a “harvesting” effect). This finding suggests that there were real and serious health effects of the smoke haze… one implication of these results on the short-term effects of the smoke haze in Malaysia is that the effects in Indonesia itself are likely to have been tremendous. The presence of significant mortality effects in Malaysian cities that are several hundred miles away from the main fires strongly supports this notion. Unfortunately, there are no appropriate health or mortality data for Indonesia to study this issue directly.”

In plain language, the acute (immediate) death rate among elderly people (excluding deaths due to accidents or violence) increased by 70% when API readings exceeded 210.

We are rightly concerned about the long-term health effects of recurrent exposures to these seasonal smogs. But we already have strongly suggestive evidence that the immediate effects of smogs such as we experience now go beyond temporary distress and discomfort – they can kill.