Rice harvest just about finished around Chiang Mai, coincided with end of burning ban at end of April. Farmers now burning their fields.
They still burn even though they use tractors to plough their fields. It's local tradition. Last night pm2.5 concentration over 120 ug/m3 inside the bedroom before I turned the air filter on.
Or visit for a holiday at this time of the year. How many will read about the pollution & make a mental note to never visit, whatever the time of year?