BANGKOK: Chiang Mai was ranked for a time on Wednesday (APRIL 24) as the third-worst major city in the world for air quality due to high levels of PM2.5 ultrafine dust, according to the Swiss firm IQAir.
It reported that Chiang Mai’s Air Quality Index was 166 on Wednesday morning, which was in the dangerous or red zone. It was ranked third after Kolkata in India and Cairo in Egypt.
