The air quality in Chiang Mai remains low, especially in Chiang Dao and Hot districts, where forest fires have been reported.
Meanwhile, in the tourist town of Pai in Mae Hong Son, the concentration of PM2.5 pollutants in the atmosphere reached 105 microgrammes per cubic metre (µg/m³), more than twice the safe threshold of 50µg/m³.
Chiang Mai governor Nirat Pongsitthaworn said state agencies are deploying their resources to fight the fires, which have been raging for about a week, blanketing parts of the city with smoke.
The air quality index (AQI) in the province's Muang district remained at moderate levels yesterday, but the figure shot up to 289 and 276 in Chiang Dao and Hot districts respectively, which is considered very unhealthy.
Also, both districts were also found to have a PM2.5 reading of 179 µg/m³ and 166 µg/m³. Prolonged exposure to PM2.5 levels above 50µg/m³ can cause serious health issues.
According to Iqair.com, Chiang Mai reported an AQI of 160 yesterday, while its PM2.5 level stood at 73.5µg/m³, which could trigger reactions among sensitive individuals.
The city was ranked 16th on Iqair's list of most polluted cities in the world. Bangkok is on the 53rd of the list.
On Saturday, Chiang Mai governor Nirat visited firefighters in Hot and Chom Thong districts and held an urgent meeting with a committee which is dealing with the Chiang Mai fires problem.
He said anyone who reports evidence of illegal burning in the forest will be given a 10,000 baht reward, if the report leads to prosecution of the offender.
Reports can be lodged to chiefs of district offices, national park offices and forest protection and fire control offices, he said.
From Jan 1 to Feb 11, there were 806 hot spots in Mae Hong Son which were affected by wildfire.