Malaysia was yesterday shrouded with haze from forest fires on the Indonesian island of Sumatra, causing "unhealthy" levels of pollution in six areas.
Haze is an annual problem during the monsoon season from May to September as winds blow the smoke across the Malacca Strait to Malaysia.
Environment Department director general Halimah Hassan said satellites had had detected 46 hotspots in Sumatra.
The Air Pollutant Index showed unhealthy levels of between 101 and 129 in six areas on Sunday morning, including two places in Malacca state along with Port Dickson and the country's largest port, Port Klang.
In the capital, Kuala Lumpur, the skies were hazy, with air pollution readings at 92, just below the unhealthy threshold.
A level of 101-200 is considered unhealthy, and 51-100 is moderate.
Halimah attributed the haze to the westerly monsoon season, during which winds blow smoke towards Malaysia. Haze, mostly caused by fires in Indonesia, builds up during the dry season.
Indonesia's government has outlawed land-clearing by fire but weak law enforcement means the ban is largely ignored.