A lingering problem
For several months, PM2.5 dust has exceeded 50 microgrammes per cubic metre (µg/m³) in many provinces in Thailand, which is considered unsafe. In some areas, such as Chiang Mai, Chiang Rai and Mae Hong Son, PM2.5 levels have reached over 500µg/m³. While some people are aware of the dangers of PM2.5 pollution, others do not take it seriously.
Source: bangkokpost.com