Drone footage shows heavy smog from illegal agricultural burning blanketing northern Thailand.

Choking air pollution covered homes and buildings as forest fires caused by slash-and-burn harvesting of crops raged in Chiang Mai province on February 28.

The blaze broke out in the Ob Luang National Park, with smoke spreading from the woods into the urban area.

Swiss air quality company IQAir reported that Chiang Mai was ranked ninth in the world for air pollution at 9 am on Wednesday, with an 'unhealthy' Air Quality Index (AQI) of 159 and PM2.5 level of 70.9 microgrammes per cubic metre.

Dangerous levels of deadly PM 2.5 particles 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.