A little clarity
in the haze.

NEA’s monitoring network reports public air readings for five regions: North, South, East, West and Central. Map labels represent these reporting regions, not individual monitoring stations. The selected regional reading cannot describe street-level conditions. See NEA’s explanation and town guide.

1-hour PM₂.₅ is a particle concentration in µg/m³ used for immediate outdoor activity decisions. The 24-hour PSI is an index based on pollutant sub-indices and their specified averaging periods. They are different measurements and their thresholds are not interchangeable.

NEA publishes hourly. Clear SG checks every five minutes while open and caches upstream responses for four minutes. Air readings older than 90 minutes are marked stale; wind and rain observations older than 20 minutes are marked stale. Forecasts expire at the end of their stated valid period. A failed refresh keeps the last available observation and shows a warning. An hourly background task checks air, wind, rain, forecasts and subscriptions while the page is closed; the wind section shows its last result. Historical charts use the last 30 Singapore calendar dates, including today; today may be incomplete.

The “Typical air by hour” panel always uses 1-hour PM₂.₅, even when the other charts show PSI. Each bar averages the same Singapore clock hour across the last 30 calendar dates, using available observations. It describes historical patterns and does not recommend a best time to go outside. The latest reading is shown separately. Each candle groups hourly air readings into a Singapore-time bucket: the wick shows the observed minimum and maximum; the body joins the first and last available readings. Values are never summed. Faded candles have fewer observations than the bucket size. Wind is shown separately using current observations from the named weather station nearest the NEA regional label coordinate. It is a nearby comparison, not a colocated air sensor. Speed is converted from knots to km/h; direction is where wind comes from, and arrows point toward. The source reports a 10-minute mean wind, with minute-resolution observations. Missing observations stay missing. Official sources: NEA wind speed and wind direction.

Postal codes stay on your device and are not saved. The first two digits suggest a broad postal district, not a verified address. Where a district spans reporting regions, choose your area. Postal sectors follow URA’s postal district list; region suggestions follow NEA’s town guide. GPS coordinates also stay on your device. They are checked against Singapore’s boundary and matched to the nearest official regional label coordinate. This is an approximation; these coordinates are not individual sensor locations. You can always choose a region manually. Your selected region and advice profile are saved on this device.

Alert rules, browser push endpoints and encryption keys are stored securely on the Site and linked to your ChatGPT identity. GPS is never saved. Remove an alert to stop it. Only threshold crossings after subscribing trigger alerts; delivery is best-effort, not an emergency warning service.

NEA PM₂.₅ feed · NEA PSI feed · NEA health advisories. Guidance here paraphrases NEA’s 1-hour PM₂.₅ activity advice. Follow your clinician’s advice if you have a medical condition. If you feel unwell, seek medical advice. Map boundary: geoBoundaries (CC BY 4.0); region shading is approximate.