Footage shows smog lingering above homes in Bangkok, Thailand, this morning amid predictions that this year's pollution will be worse than ever.

The annual air pollution haze season - caused by agricultural burning - usually starts around December and lasts until April but clouds of deadly PM2.5 dust have already been shrouding the semi-developed city.

Incompetent officials have not tackled the issue for several years, with bungling Bangkok mayor Chadchart Sittipunt even blaming incense sticks for the clouds of killer particles.

The Pollution Control Department warned that ultra fine dust levels will be worse this season due to drier weather.

Scientists found that smog is at its worst in the country when farmers burn waste crops to cheaply clear their land. 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 return every year 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.'