About Haze Day and how our data works

Haze Day (haze.day) is a free, ad-free haze (PM2.5) service for Southeast Asia. It shows current readings, causes and weather, and turns the numbers into concrete advice for exercise, school, commuting, home and pets. Where an official feed exists we show only official data; elsewhere figures are clearly labelled model estimates.

Official data vs model estimates

Singapore: readings come from NEA (data.gov.sg). If the official feed is temporarily unavailable we show “unavailable”, never a model number in its place.
Other places: there is no stable open official API yet, so we show the CAMS atmospheric-model estimate (via Open-Meteo), labelled “model estimate, not official”, with a link to the local official site.
Trend and 24-hour curves are model forecasts, calibrated to the official reading in Singapore, and are indicative only.

How often it updates

Singapore's official readings are published hourly and we check about every 5 minutes; each page shows the data timestamp. Fire detections come from NASA FIRMS satellite passes, a few times a day.

How the advice is set

Advice is based on NEA's 1-hour PM2.5 bands (55 / 150 / 250 µg/m³) and the 110 cut-off many youth leagues use, with extra caution for children, pregnant people and anyone with asthma or heart/lung conditions. It is general information, not medical advice; see a doctor if you feel unwell.

Sources

Coverage, cadence, limits and terms for every source are on the data sources pages.

How we use AI

AI is used only to explain existing data in plain language, summarise multilingual news and answer bot questions; it never produces readings. It is given only the page's facts and asked to stay within them.

Found an error?

Please open an issue at GitHub Issues with the page link and the number you saw. We check and correct promptly.

General information, not medical advice. Follow your doctor and your school, league or organiser's final call. Data come from official sources; see data sources.