air pollution over chiang mai city, levels of particulate matter smaller than 2.5 microns (

aerial air pollution architecture asia background bangkok building buildings business city cityscape danger dirty downtown dust environment fog hazardous haze health high landmark landscape metropolis mist modern office outdoor pm25 problem respiratory system sky skyline skyscraper smog smoke sunrise sunset thailand tourism tower travel unhealthy urban view chiang mai march 2019: levels particulate matter smaller microns pm2 2 5