CityNews – Smog has finally encroached into Chiang Mai, with over 20 micrograms of dust (not over 10 microns in size) per cubic metre over the safe level measured near Doi Suthep. Measurements were taken at the Ambient Air Quality Monitoring Station in Bhubing Rajanives Palace, close to Doi Suthep. Clean air should have no more than 120 micrograms of dust per cubic metre. Residents have noticed