Smog has made its annual return to Bangkok and is expected to continue into February, with outdoor burning banned for now and people working on the streets advised to wear masks.
City Hall has begun spraying water in the streets and work at big construction sites was ordered suspended.
People working outdoors were advised to wear masks.
Pongsakorn Kwanmuang, spokesman of the Bangkok Metropolitan Administration, said PM2.5 levels averaged 74.6 mcg/cm in Bangkok on Tuesday. In Thailand, 50mcg/cm is the set safe level, higher than most countries.
The smoggy conditions would probably prevail in Bangkok until February, he said.
The Pollution Control Department reported Bangkok's highest PM2.5 level of 118mcg/cm on Din Daeng Road in Din Daeng district, followed by 102 on Charoen Nakhon Road in Khlong San district, 100 on Ma Charoen Road in Nong Khaem district, 94 on Srinakarin Road in Prawet district and Tha Phra intersection in Bangkok Yai district, and 93 on Sam Sen Road in Phra Nakhon district.
Spokesman Lt Gen Kongcheep Tantrawanit said Deputy Prime Minister Prawit Wongsuwon had ordered agencies to stop farmers burning field trash, ask industries to reduce production, facilitate traffic flow, limit construction times and put vehicles spewing black smoke off the roads, to reduce smog levels.
Attapol Charoenchansa, director-general of the Pollution Control Department, said officials increased vehicle emission checkpoints and outdoor burning was strictly banned in Bangkok and vicinity until Thursday.
Nattapol Nattasomboon, director-general of the Meteorological Department, said air over the city would remain stagnant for another day or two, and the accompanying smog. The air was then expected to gradually improve.
Health Department deputy director-general Danai Teewanda said school morning assembly should be kept to 10-15 minutes to limit the health impact on students.
He said vendors, taxi motorcyclists and others working on the streets were at high risk and they should wear face masks.