You can usually smell it before the news reports it: that faint, sour, burnt-leaf note in the air, the skyline turning the colour of weak teh. When the haze arrives, the most useful haze season health tips come down to four moves: check the air quality reading daily, cut outdoor exertion when levels are unhealthy, clean the air where you sleep and work, and use a well-fitted N95 mask if you must be outside for long.
Everything else, from sore eyes to itchy skin, is about damage control. Here's how to do each part properly.
Key takeaways
- Haze is mainly fine particulate matter (PM2.5) from land and peat fires; the particles are small enough to reach deep into the lungs and enter the bloodstream.
- The WHO's 2021 air quality guidelines recommend 24-hour PM2.5 exposure stay below 15 µg/m³, a level regularly exceeded many times over during haze episodes.
- Malaysia's Air Pollutant Index (API) above 100 is classed as unhealthy; that's the point to move workouts indoors and limit time outside.
- N95 masks filter at least 95% of fine particles when fitted well; surgical and cloth masks offer much less protection against haze.
- A HEPA air purifier in the bedroom, with doors and windows closed, is one of the most effective home measures.
What is haze, and why is it harmful?
The transboundary haze that affects Malaysia, Singapore and parts of Indonesia and southern Thailand mostly comes from land and forest fires, especially smouldering peatland in Sumatra and Kalimantan. It tends to peak in the drier southwest monsoon months, though timing and severity vary a lot from year to year.
The main health concern is PM2.5: particles 2.5 micrometres across or smaller, about 30 times thinner than a human hair. The World Health Organization notes that these particles can penetrate deep into the lungs and enter the bloodstream, and long-term exposure is linked to heart disease, stroke, lung cancer and respiratory illness.
Short-term exposure matters too. During bad haze, clinics typically see more people with asthma flare-ups, bronchitis, and eye and throat irritation. A modelling study published in Environmental Research Letters estimated that smoke from the severe 2015 fire season was associated with around 100,000 excess deaths across Indonesia, Malaysia and Singapore. Estimates like this carry wide uncertainty, but the direction is clear: severe haze is a genuine public health event, not just an inconvenience.
How do you read the air quality index?
Malaysia's Department of Environment publishes hourly Air Pollutant Index readings for monitoring stations nationwide on its APIMS website. Singapore's National Environment Agency publishes the PSI and one-hour PM2.5 readings on haze.gov.sg. The bands are broadly similar:
| API / PSI reading | Category | What to do |
|---|---|---|
| 0–50 | Good | Normal activities |
| 51–100 | Moderate | Normal for most; sensitive people watch for symptoms |
| 101–200 | Unhealthy | Cut prolonged or strenuous outdoor activity; sensitive groups minimise time outside |
| 201–300 | Very unhealthy | Avoid outdoor exertion; everyone limits time outside |
| Above 300 | Hazardous | Stay indoors as much as possible; follow official advisories |
Check the station nearest you, not just the national headline figure. Conditions can differ sharply between, say, Klang and Cheras on the same afternoon.
Haze season health tips for your lungs
- Move exercise indoors when readings pass 100. Hard exercise makes you breathe faster and deeper, drawing more particles in. Swap the evening run at the park for a gym, pool session in a covered facility, or a home workout.
- Wear an N95 correctly if you're outside for extended periods. It should seal around the nose and chin with no gaps; beards and loose fits reduce protection. N95s aren't designed for young children, and people with heart or lung conditions should ask a doctor before using one, as they increase breathing effort.
- Clean the air where you spend the most time. Choose a HEPA purifier sized for the room (look at its clean air delivery rate, or CADR) and run it in the bedroom with the door closed. True HEPA filters capture at least 99.97% of particles at 0.3 microns.
- Use your aircon wisely. Set it to recirculate, keep windows shut, and clean or replace filters more often during haze season.
- Keep medication close. If you have asthma or COPD, make sure your reliever inhaler is in date and follow your action plan.
Protecting your eyes
Gritty, red, watery eyes are one of the most common haze complaints. Rinse with clean water or use lubricating eye drops (preservative-free versions are gentler for frequent use). Resist rubbing, which can worsen irritation. Contact lens wearers may find glasses more comfortable on bad days. See a doctor if you have eye pain, blurred vision or discharge.
Looking after your skin
Skin is also a barrier against pollution, and research, including a German study of women living near heavy traffic, has linked higher particulate exposure with more pigment spots. The evidence for haze-specific skincare is limited, so keep it simple:
- Cleanse gently in the evening to remove particles and sunscreen, without over-scrubbing.
- Use a moisturiser to support your skin barrier, especially if you're in aircon all day.
- Keep wearing sunscreen. Haze scatters some sunlight but doesn't reliably block UV.
Staying well indoors
Haze days often mean long stretches in closed rooms, which comes with its own problems. Keep drinking regularly, because aircon and a sore throat both make water more welcome than you'd expect; our guide to hydration in a humid climate has practical tips. Sealed rooms and low light can also leave you sluggish by mid-afternoon, so our advice on beating the 3pm energy slump applies doubly here: short movement breaks, a glass of water and time near a window.
Who is most at risk, and when should you see a doctor?
Children, older adults, pregnant women, and people with asthma, COPD, heart disease or diabetes are most vulnerable. Outdoor workers, including delivery riders, are heavily exposed and often have the least choice.
Seek medical help promptly for breathlessness, chest tightness or pain, wheezing that doesn't settle with your usual inhaler, a persistent cough, or dizziness. Call emergency services if symptoms are severe.
This article is general information, not medical advice. Talk to a doctor or pharmacist for advice about your own situation, especially if you're pregnant, on medication or managing a heart or lung condition.
Frequently asked questions
What API level is unsafe for exercise?
Once the Air Pollutant Index passes 100, the 'unhealthy' band, it's sensible to move strenuous exercise indoors. People with asthma, heart or lung conditions, older adults and children should be more cautious and may need to limit outdoor activity at lower readings.
Do surgical masks protect against haze?
Not very well. Surgical and cloth masks are not designed to filter fine particles and usually leave gaps around the face. A well-fitted N95 respirator offers far better protection against PM2.5.
Does an air purifier really help during haze?
Yes, a HEPA air purifier can substantially reduce indoor particle levels, especially in a closed room. Choose one with a clean air delivery rate suited to the room size and keep doors and windows shut while it runs.
Can haze cause long-term health problems?
Long-term exposure to PM2.5 is linked to heart disease, stroke and lung disease, according to the WHO. Short haze episodes mainly cause acute symptoms, but reducing exposure where you can is worthwhile, particularly for vulnerable groups.
Is it safe to open windows during haze?
It's best to keep windows closed when air quality is unhealthy. Ventilate briefly when readings improve, such as after rain, and check the API for your area before opening up.
Sources
- World Health Organization: Ambient (outdoor) air pollution fact sheet
- World Health Organization: Global air quality guidelines (2021)
- Department of Environment Malaysia: Air Pollutant Index of Malaysia (APIMS)
- National Environment Agency Singapore: Haze updates
- US EPA: Air cleaners and air filters in the home
- AirNow: Air Quality Index basics
- Ministry of Health Malaysia
