Air pollution remains severe as a choking mist continued to shroud northern Thailand.

Footage shows the grey-orange haze in Phayao province, reducing visibility on roads and prompting residents to retreat into their homes.

The PM2.5 level in the Mueang Phayao District had reached 207 micrograms per cubic metre, with a "very unhealthy'"AQI of 317.

Dry weather, illegal burning, and forest fires have been blamed for the persistent toxic smog. Chiang Mai and Chiang Rai, along with Pai in Me Hong Son province, have also been among the worst affected areas.

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 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.

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".

He also added: "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".

Air pollution remained severe this morning as a choking mist continued to shroud northern Thailand.

Footage shows the gray-orange haze in Phayao province, reducing visibility on roads and prompting residents to retreat into their homes. The PM2.5 level in the Mueang Phayao District had reached 207 micrograms per cubic metre, with a 'very unhealthy' AQI of 317.

Dry weather, illegal burning, and forest fires have been blamed for the persistent toxic smog. Chiang Mai and Chiang Rai, along with Pai in Me Hong Son province, have also been among the worst affected areas.

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 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.

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.'