The Bangkok Metropolitan Administration (BMA) said that an unpleasant smell in many parts of the capital on Wednesday night was caused by a sudden change of weather mixed with pollutants in the air.

Pornphrom Vikitsreth, an adviser to Bangkok governor Chadchart Sittipunt, spoke on Thursday after many people complained about a burning smell and smog in the city on Wednesday night.

Mr Pornphrom said the wind direction had shifted and was coming in from the east rather than from the Gulf of Thailand as usual.

Many smog hotspots were also detected in nearby provinces over the past 24 hours.

The fluctuating climate aggravated by thunderstorms and high air pressure from the Northeast led to the increase in dust, he said.

This was compounded by the high humidity, which increased the level of PM2.5 pollution.

The haze was also likely caused by gases, including nitrogen oxide and sulphur dioxide, that react to the sunlight and turn into dust, he said, adding this has been a problem for several months.