AQHIs are calculated based on the cumulative health risk attributable to the 3-hour moving average concentrations of four air pollutants namely, ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and particulate matter (PM2.5 / PM10). The risk factors of each pollutant were obtained from local health studies. The potential health effects of air pollutants are listed in here.
The health effects of air pollution depend on the concentrations of the air pollutants and the duration of exposure. Exposure to moderately high pollution levels for a short period of time normally will not lead to significant health problem.
The AQHI informs you of the short-term health risk of air pollution and helps you take precautionary measures to protect your health.
The AQHIs are reported on a scale of 1 to 10 and 10+ and are grouped into five health risk categories as shown below.
The general AQHI is more relevant to most of us as it represents the air pollution that we are exposed to for most of the time. The roadside AQHI is relevant to those who spend several hours continuously in a day in busy streets. The EPD has provided advice to public regarding precautionary actions to take for such levels.