A fire that started from illegal forest burning swept through a mountain, causing severe air pollution in northern Thailand.

Aerial footage shows smoke blanketing Doi Suthep mountain as firefighters scrambled to contain the fire in Chiang Mai province on March 12.

Somnuek Taopa, chief of forest fire control at Protected Areas Regional Office 16, said ground staff and helicopters from the Department of National Parks, Wildlife, and Plant Conservation were deployed to extinguish the blaze.

Chiang Mai Governor Nirat Pongsitthaworn said the level of toxic PM 2.5 particles in the air was rising due to the forest fire, and westerly winds blowing in fumes from neighbouring countries.

He pleaded for whistleblowers to report illegal agricultural burning and offered rewards of 10,000 baht (220 GBP).

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.

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.

They warned hospitals in December 2023 to prepare for an influx of patients.

It came as researchers from Peking University in Beijing, China, also discovered that long-term exposure to particulate matter PM.25 air pollution is associated with an increased risk of lung cancer.

In December, Dr Krittai Thanasombatkul from Chiang Mai, Thailand, died of lung cancer. He had previously blamed PM 2.5 microdust particles for his condition.

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

While 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.