Severe haze pollution has not only posed a health hazard to residents in Chiang Mai, but also hit tourism.

Concerned parties have urged the government to come up with long-term measures to deal with the problem, including pushing for the "clean air'' bill pending deliberation in parliament.

The PM2.5 pollution choking the upper northern provinces, including Chiang Mai, has stoked hopes among residents that the new government after the May 14 general election will tackle the problem mainly caused by slash-and-burn agriculture and man-made forest fires.

Satellite images showed that from January until this month, Myanmar had the most hotspots among Thailand's neighbours with 275,000 hotspots, followed by Laos with 220,000, Thailand with 154,000, and Cambodia with 100,700.

In the upper North, Chiang Mai recorded the highest number with 12,000 during the four-month period with more than 150,000 rai of land destroyed by fires.

From March until recently, PM2.5 levels and the worsening AQI in the northern province ranked top among the world's worst air pollution. On some days, PM2.5 levels exceeded 800-900 microgrammes per cubic metre (µg/m³), exceeding the standard level of 50 µg/m³.

The Thai Hotels Association's Upper Northern Chapter said the severe haze pollution in the North, particularly in Chiang Mai, is affecting the local economy, especially the hotel business.

Activities and promotional campaigns were rolled out to attract tourists to Chiang Mai during Songkran, but the haze pollution discouraged many.

It was initially estimated that 65% of more than 50,000 hotel rooms in Chiang Mai would be booked, but only 40% were actually reserved, the chapter said.

"Everyone expected more tourist arrivals this year as a vast array of activities were organised after Covid," the chapter's president said. "But the number of tourists dropped by 30% because of the air pollution.''