Note:
A sub-index value of 1 to 50 of a pollutant indicates that the level of the air pollutant for the day is in the good range and within the USEPA annual mean ambient air quality standard. A sub-index of 51 to 100 indicates the level of the air pollutant is in the moderate range, but still within the USEPA 24-h ambient air quality standard.

⁺Sub-index for Nitrogen Dioxide is reported only when the one-hour Nitrogen Dioxide concentration exceeds 1130µg/m³).

*Based on the highest indices in accordance with the USEPA guidelines for PSI reporting.

Current & Previous Month 24-hr PSI Readings for Singapore