Just before COVID I flew to Siem Reap during the smokey season, it was way less polluted than Chiang Mai and Bangkok. Cycling around SanSai earlier this week, plenty of forest fires to cycle past. Every morning when I open the doors i can smell the wood smoke.
Thailand is the only country responsible for the pollution in Thailand.
All this 'other countries are causing the pollution' is just lies.
No Thai will accept responsibility for the problems they cause, it's always someone else's fault!