Haze in the northern provinces of Chiang Mai, Lampang, Lamphun and Phrae has reached levels that can be harmful to health, the Disaster Prevention and Mitigation Department (DPMD) says.
The level of dust particles measuring less than 10 micrometres, or PM10, in nine northern provinces early yesterday was between 68 and 160 microgrammes per cubic metre (ug/cu m).
The safety PM10 level is 120 ug/cu m.
The air quality index (AQI) in the nine provinces ranged from 68 to 118. Any AQI over 100 is dangerous to health, according to the Pollution Control Department.
Air quality in the four provinces has reached unsafe levels.
Chiang Mai province posted 81 ug/cu m of PM 10 and 104 of AQI. Lampang registered 160 ug/cu m of PM 10 and 118 of AQI.
Lamphun recorded 157 ug/cu m of PM 10 and 117 of AQI. Phrae posted 111 ug/cu m of PM 10 and 112 of AQI.
DPMD director-general Chatchai Promlert said the agency is working with northern provincial authorities to keep tabs on air quality and deploy water trucks to spray water to reduce dust particle levels.
All parties are working together to prepare equipment to combat bush fires and smoke, he said, adding public relations campaigns have been launched to warn the public about the impact of haze on their health.
People are also urged to avoid setting fire to rubbish or other farm waste to reduce the intensity of the smoke, Mr Chatchai said.
They are warned not to carry out outdoor activities for long periods and they should wear face masks when they go outside for their own protection so as not to inhale the dust, he said.
Motorists also should take precautions when driving due to the poor visibility, he added.
Dulyawit Ratanapak, chief of the Phayao Office of Natural Resources and Environment, said Phayao is shrouded by haze.
The office and others in the area has deployed special task forces to combat wildfires and smoke in the province.
Patrol units were sent to prevent people from starting fires, Mr Dulyawit said, adding water trucks were also sent to spray water to dissipate the dust.
The work is also aimed at curbing the haze problem ahead of the University of Phayao's graduation ceremony today, which will be chaired by HRH Princess Maha Chakri Sirindhorn.