The Malaysia haze and its health economic impact
Key findings
The 1997 Asian haze caused an estimated 19,800 to 48,100 premature deaths in Indonesia and respiratory problems affecting 20 million people across Southeast Asia.
Hospital admission costs from haze-related illness in Malaysia escalated from MYR 1.8 million (2005 episode) to MYR 118.9 million (2013 episode).
The total cost of illness from the 2013 haze alone reached MYR 410.6 million, including MYR 202.8 million in medical leave costs and MYR 958 million in lost income opportunities.
Asthma cases increased by 62% during haze days, with daily inpatient admissions rising by 31% compared to normal air quality days.
Abstract
The transboundary smoke haze has become a major concern as it had a wide-ranging impact in Southeast Asia from the aspect of public health to national economics. This review synthesizes available literature in epidemiology, economics, and haze-related studies to provide essential information for the valuation of health costs associated with haze in Malaysia.
Evidence on health economic impact was gathered through a literature review collecting information on the health effects of haze, the cost of haze-related illness, and hospitalization costs from medical conditions and hospital admissions due to haze. Articles analysed were published from 1999 to 2016.
The review found that the 1997 Asian haze episode caused an increasing trend of premature mortality and respiratory problems. Several subsequent haze episodes caused increased numbers of hospitalizations. The cost impact on hospital admission ranged from MYR 1.8 million in 2005 to MYR 118.9 million in 2013. During the 1997 haze, the incremental cost of illness was noted to be MYR 21 million, rising sharply to MYR 410 million during the 2013 haze.
Background
Haze is a transboundary pollution phenomenon that occurs when the density and extent of smoke from large-scale fires is so great at the source that it remains at measurable levels after crossing into another country’s airspace. Since 1982, haze pollution has become an almost annual occurrence in Southeast Asia, with the worst episodes occurring during 1997–1998, 2006–2007, and 2015.
In Malaysia, the primary source of haze is open biomass burning from Indonesia, though local sources including paddy field burning, palm oil plantation activity, industrial emissions, motor vehicles, and domestic open burning also contribute. The haze affects the health of an estimated 75 million people and the economies of six Southeast Asian nations — Indonesia, Malaysia, Singapore, Thailand, Brunei, and the Philippines.
Haze from biomass smoke contains a large and diverse number of chemical components with health implications. These include particulate matter (PM), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃). Particulate matter — particularly the fine fraction PM₂.₅ — is the dominant component during haze events, reaching levels 4–5 times higher during haze days compared to normal conditions. PM₂.₅ particles are small enough to penetrate deep into the respiratory system and significantly affect the cardiovascular system.
Health effects of haze
The review examined eight studies covering different haze episodes across Southeast Asia. The health effects documented include increased premature mortality, respiratory illness, cardiovascular problems, and a range of symptoms affecting daily life.
The 1997 Asian haze
The worst-documented haze episode caused an estimated 19,800 to 48,100 premature deaths in Indonesia, where the fires originated from approximately 45,600 km² of burning vegetation across Kalimantan and Sumatra. In Malaysia, a one-unit increase in Air Pollution Index (API) was associated with 0.055 additional cases of respiratory symptoms per 10,000 people. Singapore saw a 30% increase in emergency department respiratory presentations, including a 19% rise in asthma and 26% rise in rhinitis. Thailand experienced an 8% increase in outpatient respiratory symptoms.
Later haze episodes (2000–2013)
A case-crossover study covering Malaysian haze events from 2000 to 2007 found elevated odds ratios for both natural mortality (OR 1.41) and respiratory mortality (OR 1.19). During the 2013 haze, a survey documented widespread symptoms among the general population: coughing (37.5%), eye irritation (36.1%), blurred vision (23.6%), and throat irritation (21.9%). In Indonesia, the 2013 haze caused throat discomfort in 68.8% of respondents, nose discomfort in 64.1%, and eye discomfort in 60.7%.
Hospitalization trends in Malaysia
Two cross-sectional studies documented the impact of haze on hospital admissions in Selangor and Kuala Lumpur. During the 2005, 2006, 2008, and 2009 haze episodes, an excess of 1,707 inpatient cases was recorded — equivalent to 2.4 additional admissions per 10,000 population. This translated to approximately 142 additional cases monthly or 4.7 daily.
A closer analysis of the 2005 and 2006 haze periods found that daily inpatient rates rose from 0.41 (normal days) to 0.53 (haze days), representing a 31% increase or 90 excess cases. Pneumonia, ischaemic heart disease, upper respiratory tract infections, asthma, and hypertensive disease accounted for approximately 63% of haze-related admissions. Asthma cases alone increased by 62% during haze days.
Economic impact
International comparison
Using the 1997 Asian haze as a benchmark, hospitalization costs varied significantly across affected countries. Indonesia bore the highest costs at an estimated USD 385 million in hospitalization alone, reflecting the severity of fires originating on its territory. Malaysia recorded USD 0.6 million in hospitalization and USD 1.8 million in outpatient costs. Singapore recorded USD 0.1–0.5 million in hospitalization and USD 0.6–1.6 million in outpatient costs.
| Country | Haze episode | Hospitalization cost (USD) | Outpatient cost (USD) |
|---|---|---|---|
| Indonesia | 1997 Asian haze | $385 million | Not reported |
| Malaysia | 1997 Asian haze | $0.6 million | $1.8 million |
| Singapore | 1997 Asian haze | $0.1–0.5 million | $0.6–1.6 million |
Malaysia’s escalating costs
Three local studies tracked the escalating economic burden of haze across different episodes. The figures reveal a dramatic increase in health-related costs over time.
| Cost measure | 1997 haze | 2005 haze | 2013 haze |
|---|---|---|---|
| Hospital admission cost | — | MYR 1.8 million | MYR 118.9 million |
| Total cost of illness | MYR 21 million | — | MYR 410.6 million |
| Medical leave costs | — | — | MYR 202.8 million |
| Reduced activity days | — | — | MYR 69.3 million |
| Loss of income opportunities | — | — | MYR 958 million |
The incremental cost of illness rose from MYR 9.5 million during the 1997 haze to MYR 410.6 million during the 2013 haze — a more than 40-fold increase. The 2013 analysis also captured previously unmeasured costs including MYR 202.8 million in medical-related leave, MYR 69.3 million in reduced activity days, and an estimated MYR 958 million in lost income opportunities.
The 2013 haze demonstrates that health costs alone represent only a fraction of the total economic impact. When medical leave, reduced productivity, and lost income are factored in, the true cost to Malaysia’s economy exceeds MYR 1.7 billion from a single haze episode.
Implications and conclusions
The haze poses a serious and escalating health threat to Malaysia and the broader Southeast Asian region. Recurring episodes have driven a growing burden of respiratory and cardiovascular illness, with hospitalization rates rising consistently across studied periods. The economic costs — spanning hospital admissions, medication, medical leave, and lost productivity — have increased dramatically from millions to hundreds of millions of ringgit.
The authors recommend that health facilities, staffing, and resources be planned with haze events in mind, and call for serious international discussion and legislation to address the transboundary sources of haze pollution. Beyond health costs, the haze impacts tourism, business operations, and transportation — making the total economic damage substantially higher than health costs alone.
Given that haze has become an almost annual occurrence in the region, preparedness and cross-border cooperation are essential to managing both the immediate health effects and the long-term economic burden.