The burning season and PM2.5

From roughly January to April, northern Thailand fills with smoke from field and forest burning (เผา), and Chiang Mai can briefly rank among the most polluted cities in the world. Bangkok gets its own ฝุ่น from December to February, when traffic fumes are trapped by still, cool air. Thais follow the ค่าฝุ่น on apps such as Air4Thai or IQAir the way they check the weather, and schools sometimes close on the worst days. Sensible habits: an N95 หน้ากาก outdoors when the reading is high, a เครื่องฟอกอากาศ in the bedroom, windows shut, and exercise indoors. If you have asthma or are planning a trip north in March, check the readings first.