Selfish farmers continued burning fields despite the soaring air pollution in Thailand.

Aerial footage shows roadside fields blackened from slash-and-burn agriculture in Nakhon Ratchasima province, on February 14.

Thick smoke drifted towards the highway, reducing visibility as the fire threatened low-lying power cables near the road.

Air quality monitor IQAir reported that the province saw 23.6 microgrammes of PM2.5 fine dust pollutants per cubic metre of air on February 14. The air quality was at 78 US AQI or 'moderate'.

The agricultural fire is just one of thousands burning across Thailand - and tens of thousands more across Southeast Asia - which cause chronic seasonal air pollution that has been cited as a reason for rises in respiratory illnesses, including cancer and emphysema.

Under Section 220 of the Thai Criminal Code regarding arson, anyone who starts a fire that causes property damage or physical injury may face up to seven years in jail and a fine of up to 14,000 baht (330 GBP).

Crop burning is considered a nuisance under Section 25 of Thailand's Public Health Act of 1992. The same act says those who fail to comply with local ordinances by continuing to engage in crop burning may be punished with up to three months in prison, a fine of up to 25,000 baht (590 GBP), or both.

But despite the continued health concerns, and hospital data showing rises in the number of deaths from chest illnesses, benighted government officials fail to tackle the issue - instead focusing on lucrative tourism campaigns such as legalizing casinos and cannabis.

Scientists found that smog is at its worst in Thailand when farmers burn waste crops to cheaply clear their land between late October and April. The agricultural process known as 'slash and burn' is quicker and easier than crop rotation fields and leaves a nutrient-rich layer of ash that helps to fertilise new crops.

However, the side-effect is severe air pollution full of toxic PM2.5 particles that cause respiratory ailments. The pollution has also worsened in recent years due to the rising demand for food from rapidly developing cities in Southeast Asia.

The lack of wind and rain during the same period, combined with a winter low-pressure system in which cold air is trapped closer to the ground by warm air above, prevent the smog from being dispersed naturally by wind.

Thailand's government has been criticised for failing to tackle the country's air pollution crisis, with bizarre measures such as spraying water into the air, placing giant purifiers on roads and even using cloud-seeding planes to cause downpours. There have also been claims that they are under pressure from powerful food conglomerates to allow the intensive farming methods.

Data scientist engineer Worasom Kundhikanjana said that the pollution will keep returning without draconian policies banning agricultural burning.

She 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.'