Thick smog obscured the sky as seasonal air pollution continues to plague northern Thailand today.

Footage shows a bird's eye view of homes shrouded by the carcinogenic haze in Chiang Mai.

Police Aviation Division pilots riding an AW 189 helicopter took off form the Chiang Mai airport, flying through reduced visibility to monitor the situation.

Swiss air quality company IQAir reported that the PM2.5 level in the province that day was at 100 microgrammes per cubic metre while the air quality index registered 175, falling in the 'unhealthy' range.

The safe level set by the World Health Organisation is five microgrammes per cubic metre.

Medics in Thailand reported this week that lung cancer deaths in the north of the country - the area hit worst by PM 2.5 pollution - have soared from 20.3 per 100,000 people in 2010 to 30.7 in 2019.

Associate Professor Chalerm Liewsisakul of Chiang Mai University's Faculty of Medicine said the last decade has seen a 'notable deterioration in air quality in the region correlating with an increase in lung disease cases'.

Dangerous levels of deadly PM 2.5 particles - which cause cancer and other debilitating illnesses - are recorded every year in Thailand between December and April when farmers across Southeast Asia burn waste crops to clear their land.

The rudimentary method, known as 'slash and burn', is quicker and cheaper than modern machinery, leaving relatively poor landowners unwilling to heed environmental and health concerns over economic necessity.

Despite paying lip service for several years, politicians have failed to stop individuals from burning their land due to it being cheaper and easier than modern farming methods.

In March 2023, the Public Health Ministry of Thailand reported that around 1.3 million people in the country had been unwell due to the rising levels of air pollution. Officials said 200,000 residents were hospitalised in a single week.

Researchers from Peking University in Beijing, China, found that exposure to PM 2.5 air pollution is associated with an increased risk of lung cancer.

In December, Dr Krittai Thanasombatkul from Chiang Mai - one of the world's worst cities for air pollution - died of lung cancer. He had previously blamed PM 2.5 microdust particles for his condition.

The New York State Department of Health says PM 2.5 also increases the risk of heart disease, asthma, and low birth weight.

Medics from South Korea published research in the National Institute of Health in the United States that said the pollutant increases the risk of stroke, ischemic heart disease, chronic obstructive pulmonary disease (COPD), lung cancer, and other illnesses such as immune deficiency and even obesity.