Environment minister G. Palanivel said the air pollutant index (API) hit 750 – a 16-year high for Malaysia – in the town of Muar on Sunday morning, with two other towns also reaching hazardous levels.
“The prime minister has signed a declaration of emergency for Muar and Ledang districts,” Palanivel told AFP in a text message.
Haze is an annual problem during drier summer months, when westerly monsoon winds blow smoke from forest fires and slash-and-burn land-clearing on the Indonesian island of Sumatra across the Malacca Strait to Malaysia and Singapore.
Malaysia’s API indicated that the capital Kuala Lumpur was also experiencing “unhealthy” air which has limited visibility to one kilometre, according to Palanivel.
The highest ever API reading was 860 during the 1997-1998 haze crisis that gripped the region.
An emergency was declared in 2005 when readings soared above 500.
Hundreds of schools have been closed since Thursday in Muar, which has a population of about 250,000.
Many Malaysians have begun wearing face masks as a precaution as the pollution levels have climbed.
The annual haze problem is blamed by Indonesia’s neighbours for affecting tourism and public health.
Singapore and Indonesia have lashed out at each other in recent days after the smog hit “critical” levels which the island-state said was potentially life-threatening to its ill and elderly.
Indonesia’s government has outlawed the use of fire to clear land, but weak enforcement means the ban is largely ignored.
Indonesia, meanwhile, has blamed Malaysian and Singapore-based palm oil companies for allowing slash and burn on estates they own on Sumatra.
The haze hit its worst levels in 1997-1998, costing Southeast Asia an estimated $9 billion from disruptions to air travel and other business activities.