Chiang Mai, a city renowned for its rich cultural heritage and scenic landscapes, has faced a recurring environmental crisis due to PM2.5 pollution. This fine particulate matter, measuring less than 2.5 micrometers in diameter, poses severe health risks and significantly impacts the quality of life for residents and visitors. The issue is particularly severe during the dry season, typically from February to April, when air pollution reaches hazardous levels. Understanding the history, causes, and effects of PM2.5 pollution in Chiang Mai is crucial for developing effective mitigation strategies.