The Thai Air Force has started cloud-seeding missions to make rain which they hope will reduce air pollution in northern Thailand - which had the world's highest levels of pollution today.

The Royal Rainmaking Centre in northern Thailand deployed two CASA agricultural planes to generate rainfall across 26 areas in the provinces of Chiang Mai, Chiang Rai, Lamphun, and Lampang on March 26. They continued the bizarre trips on Monday.

The Pollution Control Department said PM2.5 dust readings in Chiang Rai were at 232 micrograms per cubic metre. The province's Mae Sai district saw an alarming 542 micrograms per cubic metre reading.

The safe PM2.5 threshold in Thailand is 50 micrograms per cubic metre.

Chiang Mai - once one of the most popular travel destinations - now faces having its tourism industry decimated by air pollution that politicians are unable or unwilling to solve due to its connection to the lucrative agricultural industry.

Rangsan Budmueaung, director of the Royal Rainmaking Operations Centre in the upper northern region, said a meeting was held on Sunday to tackle air pollution and forest fires that are causing the toxic smog and razing agricultural areas.

Rangsan said the cloud seeding mission was launched to purify the air, minimise dust levels, and avert forest fires.

Thai health experts have warned that prolonged exposure to PM2.5 fine dust can lead to lung damage, cardiovascular diseases, and cancer.

Dr. Suwannachai Wattanayingcharoenchai, director-general of Thailand's health department, told local media: 'Exposure to long-term and excessive PM2.5 will finally cause internal inflammation, damage to lung cells, cardiovascular diseases and cancer.'

Scientists found that the smog in Thailand is at its worst when farmers burn waste crops to cheaply and quickly clear their land between late October and April. This is combined with high numbers of polluting cars on the road and large construction projects across the capital.

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 – prevent the pollution from being dispersed naturally.

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.