Lahore haze now: air quality today

In Singapore it uses NEA's five regions: North, South, East, West and Central. NEA publishes one reference point per region, not boundaries, so the site shows the region whose point is nearest to you. Tap any region to switch.

Everywhere else it uses the nearest air quality monitor that has reported in the last 3 hours, if there is one within 40 km. These are official and embassy monitors collected by the World Air Quality Index project (aqicn.org). With no monitor nearby, it shows a model estimate instead and says so.

In Singapore your location never leaves your device. Elsewhere it is rounded to about 10 km before it is sent to look up the reading, and it is never stored.

In Singapore the big number is NEA's 1-hour PM2.5: fine particles in the air over the last hour, in micrograms per cubic metre. NEA calls it Normal up to 55, Elevated from 56 to 150, High from 151 to 250 and Very High above 250. The 24-hour PSI is Singapore's official index: up to 50 is Good, 51 to 100 Moderate, 101 to 200 Unhealthy, 201 to 300 Very Unhealthy and above 300 Hazardous.

Everywhere else the big number is the US Air Quality Index (AQI), the scale most air quality apps use worldwide: up to 50 is Good, 51 to 100 Moderate, 101 to 150 Unhealthy for Sensitive Groups, 151 to 200 Unhealthy, 201 to 300 Very Unhealthy and above 300 Hazardous. Your country may publish its own scale, such as Malaysia's API or Indonesia's ISPU, and those numbers can differ. The page links to your official source.

In Singapore the wording follows NEA's guide for 1-hour PM2.5 and the Ministry of Health's advisory for 24-hour PSI. When the two readings point to different advice, the site shows the stricter one and says which reading it came from.

Everywhere else it follows the US EPA's advice for each AQI level. "With kids or elderly" switches to the advice for sensitive groups: children, older adults, pregnant people and people with heart or lung conditions.

Where no monitor is close by, the reading comes from the Copernicus (CAMS) air quality forecast, a computer model of the whole atmosphere, via Open-Meteo. It covers the whole world but is coarse, and in smoke haze it can read much lower than monitors on the ground. Treat it as a floor, not a ceiling: if the air looks or smells worse, trust that and check your official source.

Sites such as aqicn.org convert PM2.5 into the US AQI, which is stricter than NEA's bands. The same air can be Elevated on NEA's scale and Unhealthy on the US one. The US scale row shows that conversion (US EPA table, 2024, using the EPA's 12-hour NowCast) so you can compare. It does not change the advice.

Readings are published about once an hour. The page checks for a new one every five minutes while it is open, and warns you if the latest is old. This is an independent site, not an official one.