Malaysia haze season — when it happens, health risks and what to do
Transboundary haze from Indonesian fires affects Malaysia every year. When is it worst, how bad can it get, and how to protect your health.
What causes the haze?
The Southeast Asian haze is caused primarily by deliberate burning of forests and peatlands in Sumatra and Kalimantan, Indonesia. Farmers use fire to clear land cheaply for palm oil and pulpwood plantations. When these fires coincide with dry El Niño conditions, the smoke can blanket Malaysia, Singapore and southern Thailand for weeks or months.
When is haze season?
The primary haze season runs from August to October, when the southwest monsoon carries smoke from Sumatra across the Strait of Malacca to Peninsular Malaysia and Singapore. A secondary haze period occurs in February-March from fires in mainland Southeast Asia (Myanmar, Laos, northern Thailand), affecting northern Malaysia less severely.
How bad can it get?
During severe haze years (1997, 2013, 2015, 2019), Malaysia's Air Pollutant Index (API) has exceeded 300 — hazardous levels that trigger school closures and flight cancellations. The 2015 crisis cost Malaysia an estimated $4 billion in health impacts and lost productivity. PM2.5 levels can reach 200+ µg/m³, more than 10x the WHO guideline.
Health protection
When API exceeds 100 (unhealthy): limit outdoor exertion, keep windows closed, use air purifiers indoors. When API exceeds 200 (very unhealthy): wear N95 masks outdoors (not surgical masks — they do not filter PM2.5), avoid all outdoor exercise, keep vulnerable people (children, elderly, asthmatics) indoors. Monitor readings at apims.doe.gov.my (Malaysia) or haze.gov.sg (Singapore).
Travel implications
Haze can ruin scenic views (Cameron Highlands, Langkawi sunsets), cause flight delays, and make outdoor activities unpleasant. If you are visiting Malaysia in September-October, check the ENSO forecast — El Niño years have the worst haze. Have a backup indoor itinerary. Kuala Lumpur's malls and museums provide excellent haze-day alternatives.
Frequently Asked Questions
Does haze affect East Malaysia (Sabah/Sarawak)? ▾
Yes — Sarawak and western Sabah can be affected by fires in Kalimantan. The 2015 and 2019 haze events severely impacted Kuching and Kota Kinabalu.
Is haze getting better or worse? ▾
Indonesia has made progress since the catastrophic 2015 event (moratorium on new peat concessions, peatland restoration), but fires still occur annually. El Niño years remain high-risk. Climate change may increase fire risk by extending dry seasons.