Cloud-seeding planes have been deployed to combat air pollution in northern Thailand.

The aircraft were dispatched to help dissipate the hazardous smog still cloaking large swathes of the northern region, the Department of Royal Rainmaking and Agricultural Aviation said on Monday.

The agency said the planes have previously been spraying water in a bid to reverse the temperature inversion phenomenon - where warm air rises and acts as a lid trapping pollutants near the ground.


Swiss air quality company IQAir reported on April 7 that the air quality in Chiang Mai was at 265 AQI with a PM2.5 reading of 215 micrograms per cubic metre. The safe level in Thailand is 50.

Chiang Mai authorities held a meeting today to discuss cloud seeding plans in the province, which has been enveloped in a toxic haze for several months.

Chiang Mai Governor Nirat Pongsitthaworn, after initial reservations, finally declared several villages in Chiang Mai 'disaster zones'. The designation would allow resources to be mobilised quickly to address the hazardous PM2.5 dust levels, which have been responsible for thousands of hospital admissions.

The Thai Meteorological Department said that northern regions in Thailand will experience thunderstorms from April 6 to 9, with residents hopeful the rains will help dissipate pollutants.

Scientists found that smog is at its worst in the country when farmers burn waste crops to cheaply clear their land between late October and April. It has been worsened in recent years by rising demand for food and powerful agro-business lobbyists that can stifle the government's control over farmers.

The seasonal lack of wind and rain, combined with a winter low-pressure system in which cold air is trapped closer to the ground by warm air above – hampers the pollution from being dispersed naturally by wind.

The Thai government has been criticised for failing to tackle the country's air pollution crisis, with bizarre measures such as spraying water into the air and giant purifiers having no impact.