The haze in Malaysia that started in late August (2026) was initially intermittent and affected areas sporadically.
Since late September (2026), it has blanketed most parts of the country and has been persistent.
There has been publicity about the acute effects of the air pollution, with reports of an increase in healthcare interactions for respiratory and eye ailments, and the Health Ministry’s purchases of respiratory devices.
However, there has been minimal public discussion on the long-term effects of air pollution on health.
Dangerous particles
Air pollution is the second highest risk factor for non-communicable diseases (NCDs) and the second leading cause of premature death, surpassed only by high blood pressure.
The World Health Organization (WHO) estimated that in 2019, ambient air pollution and household air pollution were associated with 6.7 million premature deaths annually.
About 68% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and stroke, 14% to chronic obstructive pulmonary disease (COPD), 14% to acute lower respiratory infections and 4% to lung cancers.
Common pollutants are:
- Particulate matter (PM)
The major components of this are sulphates, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water.
There is strong evidence of negative health impacts associated with exposure to PM.
- Carbon monoxide
This is a colourless and odourless toxic gas produced by incomplete combustion of carbon fuels like wood, petrol, charcoal, natural gas and kerosene.
- Ozone
At ground level (not the ozone layer in the upper atmosphere), ozone is a major component of smog formed through reaction with gases in the presence of sunlight.
- Nitrogen dioxide
This is a gas commonly released from combustion of fuels in the transportation and industrial sectors.
- Sulphur dioxide
This is a colourless gas produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores containing sulphur.
PM is used as an indicator of air pollution and is classified according to the diameter of the pollutant particles, i.e.:
- PM0.1 – Ultrafine particles less than 0.1µm
- PM2.5 – Fine particles 2.5µm or less
- PM10 – Coarse particles 10µm or less.
Affects the whole body
Toxic particles from polluted air enter the body through the nose, throat, airways, lungs and skin.
They ultimately make their way into the bloodstream, thereby spreading throughout the body.
This leads to an immune system response and disease.
Particulate matter can affect almost all organs in the body, including:
- Heart – increases the risk of cardiovascular diseases like stroke, ischaemic heart disease, heart failure and high blood pressure
- Liver – impacts the liver, spleen and blood, and increases the risk of type 2 diabetes
- Reproductive system – increases the risk of gestational diabetes and miscarriage for women, and low birth weight, premature birth and stillbirth for babies
- Brain – increases the risk of headache, anxiety, cognitive impairment and dementia
- Lungs – increases the risk of irritation, inflammation and infection; asthma; COPD; lung cancer; pneumonia; and reduced lung function
- Skin – accelerates ageing.
Children, senior citizens, pregnant women and their foetuses, and people with pre-existing conditions like asthma, COPD, ischaemic heart disease and diabetes are more vulnerable to the effects of air pollutants.
They are at increased risk of exacerbations, hospitalisations and death.
Not meeting the guidelines
The WHO Global Air Quality Guidelines (AQG) provide global guidance on thresholds and limits for key air pollutants that pose health risks.
Malaysia has nothing much to shout about.
According to the WHO, Malaysia’s 2023 annual mean of PM2.5 was 22µg/m3, which was four times that of WHO’s standard of 5µg/m3.
The WHO also attributed 21% of deaths from stroke and ischaemic heart disease in Malaysia to air pollution.
According to the 2025 State of Global Air Quality data, air pollution is among the top 10 risk factors for death in Malaysia, with more than 16,000 deaths from air pollution.
The percentages attributed to air pollution were 14% of stroke deaths, 15% diabetes deaths, 16% ischaemic heart disease deaths, 22% of COPD deaths, 12% lung cancer deaths, 12% lower respiratory infection deaths and 8% neonatal deaths.
None of the Malaysian population live in areas where PM2.5 levels are below the least stringent WHO interim target for healthy air (i.e. 35 µg/m3), while 57% of the population live in areas where PM2.5 levels do not meet the national annual standard (i.e. 15 μg/m3).
About one-third (34%) of outdoor PM2.5 levels were caused by fossil fuel combustion, i.e. the use of coal, oil and gas, and 3% of deaths due to air pollution were in children under five years of age.
Preventive measures
Most causes of outdoor air pollution are beyond individuals’ control.
As such, concerted action from policymakers in government and various sectors like manufacturing, energy, transport, waste management and agriculture are required.
Examples of successful policies that have reduced air pollution include:
- Use of clean technologies that reduce industrial emissions, improved management of urban and agricultural waste, and alternatives to incineration
- Access to affordable clean household energy solutions for cooking, heating and lighting
- Shifting to clean modes of transport, walking and cycling networks, and shifting to cleaner heavy-duty and low-emissions vehicles and fuels
- Improving energy efficiency of buildings and more green cities
- Use of combustion-free power, e.g. solar, wind or hydropower, and use of low emission fuels and renewable combustion
- Improvements in waste management, including recycling and biogas production, and where incineration is unavoidable, the use of combustion technologies with strict emission controls, and
- Low carbon development pathways for healthcare delivery.
Individuals can act to protect themselves.
Depending on the severity of the pollution, such measures include:
- Use of N99 masks that are NIOSH certified – this is the preferred option; the alternatives are KN95, KF94 and FFP2 masks that are manufactured according to Chinese, South Korean and European standards respectively
- Reduce, minimise or avoid outdoor activity
- Indoor use of air purifiers, if the reader can afford it
- Keeping well-hydrated
- Always being aware of the severity of the air pollution – the Environment Department provides real-time Air Pollutant Index (API) readings on its MyEQMS Platform, with an API above 100 considered unhealthy.
The health impact of the haze depends on the reader’s health status, the air quality as measured by the PM2.5 reading, the duration of exposure and the intensity of outdoor activity.
Children, senior citizens, the pregnant and people with chronic lung or heart conditions have to take more stringent protective measures.
It is advisable to seek medical advice whenever there is doubt.
Dr Milton Lum is a past president of the Federation of Private Medical Practitioners Associations and the Malaysian Medical Association. For more information, email starhealth@thestar.com.my. The views expressed do not represent that of organisations that the writer is associated with. The information provided is for educational and communication purposes only, and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
