Air Quality Health Index

The Air Quality Health Index (AQHI) compiled by the Environmental Protection Department 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 excess 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 (including PM10 and PM2.5 whichever has a higher risk) measured at each air quality monitoring station of the Environmental Protection Department.  The risk factors associated with each pollutant were derived from local health statistics and air pollution data.  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 station to keep you up to date of the latest air quality situation.  We also provide the AQHI forecast which serves to alert you before the onset of high health risk categories due to pollution episodes.

What the AQHI Reveals

The AQHI estimates the additional short-term health risk caused by air pollution of respiratory and cardiovascular illnesses 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 AQHI health risk categories with health advice provided.

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

When the health risk category is at the Low and Moderate levels, you can continue to enjoy your 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.

More on health advice

Monitoring Stations

Pollution levels are continuously measured by the Environmental Protection Department's air quality monitoring network, which includes 13 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 built and operated to comply with the highest international standards of accuracy.

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 by the Environmental Protection Department 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 AQHI 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 AQHI forecastDownload Air quality Health Index Mobile Applications

AQHI readings of the past 24 hours are available for those who wish to enquire further.

AQHIs for the past 24 hours

The pollutant concentration at each monitoring station is available for the last 24 hours.

Pollutant concentration for the past 24 hours

AQHI statistical summaries are available by month.

AQHI monthly summaries

More detailed hourly AQHI records are also available by month. 

Past AQHI records

Aside from these online resources, AQHI information is broadcast on radio and television, and printed in local newspapers.  You can also call the AQHI Hotline at (852) 2827 8541 if you would like to obtain information by telephone.

Other Information

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

Air pollution information from other countries
Last review date: June 2017
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