The levels of ultra-fine dust, known as PM2.5, in some areas of Bangkok and several other provinces have been either moderate or unhealthy. People are advised to check the air quality before leaving their homes or engaging in outdoor activities, said the Public Health Ministry.

PM2.5 dust levels usually go up between the end and early part of the year, the ministry said.

According to the Department of Pollution Control's air quality website, PM2.5 levels in certain provinces - particularly in the Northeast such as Nakhon Phanom, Mukdahan, Yasothon, Nong Khai and Ubon Ratchathani - are now at the moderate (yellow) level or unhealthy (orange) level.

In Bangkok, unhealthy levels were reported in several areas, including Bang Khun Thian; Din Daeng; Bueng Kum; Bang Phlat; Sathon and Khlong San.

The ministry said that before leaving their homes or doing outdoor activities, people should check the PM2.5 levels using the Air4Thai application or visit the Department of Pollution Control's website at http://air4thai.pcd.go.th. They can also visit the website https://pm25gistda.or.th to assess air quality levels:

Blue (very good): No health risk.

Green (moderate): No health risk.

Yellow (unhealthy): People with respiratory tract disorders should avoid outdoor exercise, while children and the elderly should limit outdoor time.

Orange (very unhealthy): People with respiratory tract disorders should avoid outdoor activities. Children and the elderly should restrict outdoor time.

Red (hazardous): Outdoor exercise should be avoided, and people with respiratory tract disorders should stay indoors.