Haze at work: what supervisors need to know

Why it matters

Haze carries very fine particles. They reach deep into the lungs. Workers get coughs, itchy throats, watery eyes and runny noses. People with heart or lung disease can get much worse.

Outdoor workers breathe it longest. Hard physical work makes them breathe faster and deeper, so they take in more. Poor visibility adds a second risk, because operators and drivers can't see as far.

Know which reading you are looking at

Countries report air quality differently, and the numbers do not convert. Use your own regulator's scale.

• Singapore: the PSI forecast plans the next day. The 1-hour PM2.5 reading adjusts work during the day. Both are on haze.gov.sg.
• Malaysia: the API, based on a 24-hour running average, from the Department of Environment.
• Brunei: PSI readings and health advisories from JASTRe, MOH and the Meteorological Department.

Singapore: what to do at each level

MOM added the 1-hour PM2.5 bands on 20 October 2026. Vulnerable workers are the elderly, pregnant women and people with chronic heart or lung disease.

• PSI forecast 101 to 200: healthy workers reduce prolonged or strenuous outdoor work. Elderly and pregnant workers minimise it. Workers with heart or lung disease avoid it.
• PSI forecast 201 to 300: healthy workers avoid prolonged or strenuous outdoor work. Elderly and pregnant workers minimise all outdoor work. Workers with heart or lung disease avoid it. Provide masks if prolonged or strenuous work can't be avoided.
• PSI forecast above 300: healthy workers minimise outdoor work. Everyone else avoids it. Redeploy jobs, cut intensity and duration, give regular indoor breaks and defer non-essential work. Provide masks or suitable respirators if work can't be avoided.
• PM2.5 56 to 150: healthy workers reduce strenuous outdoor work. Vulnerable workers avoid it.
• PM2.5 151 to 250: healthy workers avoid strenuous outdoor work. Vulnerable workers avoid outdoor work. Provide masks if strenuous work can't be avoided.
• PM2.5 251 and above: healthy workers minimise outdoor work. Vulnerable workers must not work outdoors. Provide masks or respirators if outdoor work can't be avoided. Give affected workers hourly rest breaks of about 10 to 15 minutes, indoors where you can.

Malaysia: what to do at each level

DOSH published the second edition of its haze guidelines in October 2026. Susceptible employees are those with heart or respiratory illness.

• API 51 to 100: prepare. Identify susceptible employees, set your criteria for stopping outdoor work, stock N95 respirators and fit-test outdoor workers.
• API 101 to 200: minimise strenuous outdoor work. Give respirators to susceptible employees working outdoors, and move them indoors if they struggle. Spray construction sites with water regularly.
• API 201 to 300: avoid strenuous outdoor work. Move susceptible employees indoors. Give respirators to everyone working outdoors. Stop earthworks and earth movements for now.
• API 301 to 400: you must give respirators to everyone working outdoors. Decide by risk assessment whether crane lifts should stop. Susceptible employees stay indoors.
• API above 400: avoid outdoor work and stop any work whose health risk can't be reduced. Emergency and essential services wear suitable respirators.

Brunei: what SHENA expects

SHENA's notice of 3 September 2026 sets no fixed action levels. It asks workplaces to treat significant haze exposure as a workplace hazard and to step up precautions as readings rise.

• Review your risk assessment when air quality, weather, work or advisories change. This falls under section 12 of the WSH Act and the Risk Management Regulations.
• Reduce, reschedule or relocate prolonged or strenuous outdoor work.
• Decide whether vehicle work, lifts and work at height should stop when visibility drops.
• Provide a properly fitted N95 or equivalent where the risk assessment calls for one.

Masks: get these right

Singapore also asks you to keep at least a one-week supply of masks in your haze plan if people work outdoors. Provide goggles if eyes get irritated.

• Use N95 or equivalent. These filter about 95% of very fine particles. Ordinary surgical masks are not what the regulators specify.
• Fit-test everyone who needs one. Singapore points to SS 548:2022. A mask that leaks does little.
• Train and supervise wearers. Change masks when soiled or damaged, or when breathing gets hard.
• Masks add breathing effort. Slow the pace, add breaks and push water. Move anyone who struggles to indoor work.
• Older and pregnant workers, and those with heart or lung disease, should see their doctor before using a mask.
• An N95 may not be enough in hazardous haze. MOM suggests full-face respirators for prolonged outdoor work when the PSI forecast is above 400.

Cranes, vehicles and indoor work

MOM and DOSH both name tower and mobile crane lifts. Put poor visibility in the risk assessment, and lift only with the right precautions in place. DOSH also advises drivers to switch on headlights at API 301 to 400.

Indoors, keep windows and doors closed most of the time, and use suitable air cleaning devices. SHENA suggests HEPA air purifiers where practical. Malaysia adds a check that air processing units on equipment can filter out the particles.

Common mistakes

• Waiting for the haze to arrive before buying masks and fit-testing.
• Checking the forecast in the morning, then not looking at the hourly readings again.
• Treating all workers the same. Vulnerable workers move first.
• Handing out masks with no fit test, no training and no extra breaks.
• Forgetting visibility in the lifting plan.
• Giving workers no way to report symptoms.

In other countries

• Indonesia: We found no labour ministry guidance specific to workers and haze. The Health Ministry publishes public advice on masks in forest fire smoke. It says N95s need an individual fit test. The general K3 duties under Law No. 1 of 1970 still apply, and local governments may issue their own circulars.

Use it on site: the haze checklist and the toolbox talk to brief your crew.

Sources

1. Additional guidance on 1-hour PM2.5 readings to protect outdoor workers during haze (20 October 2026), Ministry of Manpower.
2. Guidelines on protecting employees from haze, Ministry of Manpower.
3. What penalties can MOM impose if employers do not follow its guidelines?, Ministry of Manpower.
4. Guidelines for the Protection of Employees Against the Effects of Haze at Workplaces, 2nd edition, 2026, DOSH Malaysia.
5. 2026/WSHN/04: Workplace safety and health precautions during hazy conditions, SHENA Brunei.
6. Penggunaan masker pada asap kebakaran hutan, Ministry of Health, Indonesia.

This is practical guidance, not legal advice. Laws and codes of practice change; always check the current official text and your site's own procedures.