The Air Quality Health Index (AQHI) compiled by the Environmental Protection Department (EPD) informs the public of the short-term health risk of air pollution in Hong Kong and helps the public take precautionary measures to protect their health. The AQHIs are reported on a scale of 1 to 10 and 10+ and are grouped into five health risk categories. The AQHIs are reported hourly at each general and roadside monitoring station to keep the public up to date on the latest air quality situation.
When the category reaches High, children, the elderly and people with heart or respiratory illnesses should reduce outdoor physical exertion. When the category reaches Very High or Serious, the general public should also reduce or avoid outdoor physical exertion.