AirAware › Singapore AQI
Singapore AQI (US EPA, PM2.5 only)
As of 7:00 pm SGT, 18 October 2026, AirAware’s US AQI estimate from NEA’s 24-hr PM2.5 is highest in West at 212. This is a PM2.5-only sub-index calculated by AirAware, not an official Singapore index and not a full multi-pollutant US AQI. Singapore’s official index is the PSI.
- North155
- South173
- East177
- West212
- Central179
Not an official Singapore index, and not a full multi-pollutant US AQI.
| Region | US AQI (PM2.5) | From 24-hr PM2.5 |
|---|---|---|
| North | 155Unhealthy | 61 µg/m³ |
| South | 173Unhealthy | 87 µg/m³ |
| East | 177Unhealthy | 92 µg/m³ |
| West | 212Very Unhealthy | 137 µg/m³ |
| Central | 179Unhealthy | 95 µg/m³ |
How AirAware calculates it
AirAware takes NEA’s published 24-hr PM2.5 concentration for each region, truncates it to one decimal place, finds the pair of US EPA breakpoints that bracket it and interpolates linearly, then rounds to the nearest whole number. It uses the PM2.5 breakpoints the US EPA brought into effect on 6 May 2024. A 24-hr average is only used when at least 18 of 24 hourly readings exist. The result covers PM2.5 only; a full US AQI would also consider ozone, PM10, carbon monoxide, sulphur dioxide and nitrogen dioxide. US EPA fact sheet · Federal Register.
| 24-hr PM2.5 (µg/m³) | AQI | Category |
|---|---|---|
| 0.0–9.0 | 0–50 | Good |
| 9.1–35.4 | 51–100 | Moderate |
| 35.5–55.4 | 101–150 | Unhealthy for Sensitive Groups |
| 55.5–125.4 | 151–200 | Unhealthy |
| 125.5–225.4 | 201–300 | Very Unhealthy |
| 225.5–325.4 | 301–500 | Hazardous |
Why PSI and AQI give different numbers
Both scales run from 0 to 500 and turn pollutant concentrations into a number, but they use different breakpoints. NEA notes that Singapore referenced the US EPA system when developing the PSI, but the two are not identical. Since the US EPA tightened its PM2.5 breakpoints in 2024, the same air can fall in a worse category on the US AQI than on the PSI. The PSI also reports the worst of six pollutants, while AirAware’s AQI figure covers PM2.5 only. For decisions in Singapore, use the PSI and MOH’s advice. NEA FAQ · AirNow: AQI basics.
Sources: US EPA: PM NAAQS and AQI fact sheet (2024) · Federal Register: PM NAAQS reconsideration (2024) · NEA air pollution FAQs