Air Quality Health Index

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.  Here you can learn how the AQHI works and what it can tell you about the short-term health risk of air pollution.

How the AQHI Works?

The AQHI of the current hour is calculated from the sum of the percentage added health risk of daily hospital admissions attributable to the 3-hour moving average concentrations of four criteria air pollutants: ozone, nitrogen dioxide, sulphur dioxide, and particulate matter (PM10 or PM2.5, whichever has a higher health risk) measured at each air quality monitoring station of the EPD.  The risk factors associated with each pollutant were derived from local health statistics and air pollution data.

The AQHIs are reported hourly at each general and roadside monitoring station to keep the public up to date of the latest air quality situation.  We also provide the health risk categories forecast which serves to alert the public before the onset of high health risk categories due to pollution episodes.

What the AQHI Informs?

The AQHI estimates the additional short-term health risk caused by heart and respiratory diseases from air pollution that lead to hospital admissions.  It makes reference to the short-term World Health Organization Air Quality Guidelines as anchor points to define the level where health risk is high due to short term exposure to air pollution.  The AQHIs are reported on a scale of 1 to 10 and 10+ and are grouped into five health risk categories with health advice provided as below.

Health Risk Category AQHI
Low 1
Moderate 4
High 7
Very High 8
Serious 10+

When the health risk category is at the Low or Moderate levels, people can continue to enjoy their usual activities.  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. For more details, please refer to our health advice on the AQHI website.

More on health advice

Monitoring Stations

Air pollutant levels are continuously measured by the EPD's air quality monitoring network, which includes 15 general and 3 roadside monitoring stations.  The general stations are located in different parts of Hong Kong to cover various kinds of land use areas.  They are usually at roof level of four to six storeys high.  The roadside stations are located at street level in Causeway Bay, Mong Kok and Central.  All stations are designed and operated to comply with the highest international standards that can efficiently and accurately measure the air pollutant data.

Map showing locations of general and roadside monitoring stationsHow to determine the AQHI most relevant to you

Data and Statistics

Data collected from the monitoring stations is recorded and analysed by the EPD and turned into useful information for you in the following ways.

The current AQHI readings are available 24 hours a day, seven days a week.  The health risk categories forecast is also available to provide alerts to the public before the onset of high health risk categories due to pollution episodes.

Current AQHIs and Health Risk Categories forecastDownload Air quality Health Index Mobile Applications

The AQHI readings at each monitoring station are available for the past 24 hours.

AQHIs for the past 24 hours

The pollutant concentrations at each monitoring station are available for the past 24 hours.

Pollutant concentration for the past 24 hours

AQHI statistical summaries are available by month.

AQHI monthly summaries

All hourly AQHI records in the past are available.

Past AQHI records

In addition to the above online resources, AQHI information is also broadcasted on radio and television, and printed in local newspapers.  You can also call the AQHI Hotline at (852) 2827 8541 to obtain the latest information.

Other Information

Here provides links to the monitoring bodies of other countries so that you can learn more about air pollution problem around the world, and what is being done about it.

Air pollution information in other countries
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Last review date: April 2022