Shocking aerial drone footage shows how apocalyptic farm fires are sending air pollution levels soaring in northern Thailand.

A thick haze hovered over roads in Khon Kaen province as the levels of toxic PM2.5 particles in the atmosphere reached 154 AQI or 'unhealthy' levels on March 2.

Riders and pedestrians wore masks to avoid inhaling air pollutants while local authorities sprayed water to disperse the heavy smog.

Resident Komsan Jirasathit, 50, said the air pollution only eases during windy conditions, adding the haze has formed due to the severity of PM2.5 levels caused by fires on farmland.

He said: 'I've asked my family to wear masks when they go outside to keep from getting sick. I hope local authorities can improve the air quality soon.'

Theerasak Theetkhayuphan, mayor of Khon Kaen City, said water trucks were regularly dispatched to spray water to alleviate the dusty mist and clean roads.

He urged locals to refrain from illegal outdoor burning as they handle the smog.

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. 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.

Data scientist engineer Worasom Kundhikanjana said: 'PM 2.5 pollution has a seasonal trend in Bangkok and the northern provinces, but has only recently received public attention. During this winter haze, the harmful particle pollution level is high throughout the day, including on weekends.

'Unfortunately, spraying water into the air does not appear to be effective, since the volume of water is minuscule compared to actual rain.

'With the start of the monsoon season, the weather in Bangkok will get better, and public attention on this issue will likely fade. However, without immediate policy measures, the problem will come back again next winter.'