Residents were ordered to work from home as toxic air pollution caused by agricultural burning choked Thailand.

Residents if former tourist destination Chiang Mai - now a no-go city - were told to stay indoors as PM2.5 fine dust levels soared to up to the highest in the world.

Swiss air quality group IQ Air recorded 224.3 microgrammes of cancer-causing toxic particles per cubic metre - 45 times higher than the safe levels set by the World Health Organisatiin.

Chiang Mai Governor Nirat Pongsitthaworn said government agencies, office workers, and schools were to adopt remote work where feasible.

Restaurants were required to use air-conditioned rooms, while people with underlying health conditions were advised to completely avoid outdoor activities.

The stay-at-home measures will be effective until April 11, in time for the annual Songkran water festival which will be held over the weekend.

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.