Smoke haze particles from Indonesia's forest fires on Thursday surged beyond the safety threshold of 120 microgrammes per cubic metre.
The situation on the resort island of Phuket became critical, posing a risk to people's health, delaying flights to the south, with a potential negative effect on tourism.
The haze situation has deteriorated since Monday and was likely to worsen further if Indonesia cannot contain the forest fires that are creating the haze.