About
About Air Quality HK
A bilingual relay of the Hong Kong Environmental Protection Department's Air Quality Health Index and air-pollution data, designed to make today's air decisions easier.
What's AQHI?
The Air Quality Health Index (AQHI) is the official Hong Kong measure of short-term health risk from air pollution. It rolls four pollutants (NO₂, O₃, SO₂, particulate matter) into a single number between 1 and 10+, then groups them into five health bands from Low to Serious. The number reflects the increase in hospital admissions for respiratory and cardiovascular conditions on days with similar pollution.
Where the data comes from
Every 30 minutes we read three official EPD feeds: a summary RSS for the HK-wide current and AM/PM forecast, a per-station XML for the latest hour at each of 19 monitoring stations, and 24 hours of history for the same stations. Nothing is computed by us — we just relay, layout, and translate. The official source is EPD's AQHI site at aqhi.gov.hk.
Where the verdicts come from
The 'Should I go outside?' verdicts map directly to the EPD's published health advisory bands. We don't invent new medical guidance — we translate the official band recommendations into the activities people actually ask about: running, kids outside, opening windows, masks.
Geolocation
If you choose to share your location for the on-page verdict, the math runs in your browser only. Coordinates are never sent to our servers, never logged, never stored. Permission can be revoked at any time in your browser settings.
Email alerts — what we store
If you sign up for email alerts, we store: your email address, the AQHI threshold you picked, your locale (EN or zh-HK), and either the station code or the rounded coordinates you chose to watch. Coordinates are stored at the precision you submitted — we don't reverse-geocode and we don't store anything else. Each alert email contains a one-click unsubscribe link, and clicking it deletes your row from our database immediately. Unconfirmed signups (where you never clicked the confirmation link) are auto-deleted after 7 days.
Limitations
AQHI is a 3-hour rolling average, so abrupt changes lag the reading by an hour or so. The 'forecast' covers the rest of today only; we don't predict tomorrow. EPD's per-station feed occasionally has gaps after maintenance — when this happens we drop the affected station from the map for that hour.
Who built this
Built by StudioGKO. Not affiliated with the Hong Kong EPD.