Singapore Air quality report with 24hr PSI/AQI, 1hr PM2. 5 24Hr PM2. 5, 24Hr particulate matter sulphur dioxide nitrogen dioxide ozone and carbon monoxide Features: 1hr PSI/AQI Widget. NOTIFICATION service hourly on hazy day base on 1hr PM2. 5 PSI/AQI > 100, 24hr PSI/AQI>100 or Sumatra Hotspot count>100.