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HKUST Develops Personalised Real-time Air Quality Informatics System

Image Credits: HKUST, Press Release

The HKUST Institute for the Environment (HKUST-IENV) recently launched the “PRAISE-HK-EXP App” – a new mobile app that helps users analyse their personal air pollution exposure budget, from outdoor, indoor, to different micro-environments including various modes of transportation, so that they can better manage their exposure to air pollution in different micro-environments.

Thanks to the 150th Anniversary Charity Program by a major global financial company and bank, the PRAISE-HK system has three major release milestones for the mobile app:

  • Phase 1– Released on 21 June 2019, the PRAISE-HK App profiles a highly accurate “outdoor” air quality map down to the street level, with resolution down to 2-20 metres.
  • Phase 2 – Released on 24 November 2021 the PRAISE-HK-EXP App provides a detailed account of air pollution exposure risks accumulated throughout the day (including outdoors – on the streets, indoor – inside buildings or on different transport modes). It also shows users what they can do to reduce their air pollution health risks during polluted episodes.
  • Phase 3– Will be a health alert app that provides user-specific alerts based on the user’s personalised history of symptoms reported by users in air quality sensitive subgroups.

The PRAISE-HK-EXP App released most recently represents the completed technological core of the PRAISE-HK system. The phase 1 App launched 2 years ago has laid a solid foundation in providing a state-of-the-art real-time analysis and 48-hr forecast, highly accurate and detailed (down to 2-20 metre resolution), “outdoor” air quality information for users, but it does not provide the user with indoor information, or specific recommendation about what they can do to reduce their air pollutant exposure risks.

The second phase of the app (PRAISE-HK-EXP) released on 24 November 2021 is an air pollution exposure tracker. With the user’s authorisation, the app tracks and delivers a personalised exposure budget throughout the day, as users move from one microenvironment to another, indoor and outdoor. It shows users when, where and during what activity they receive the largest dose of air pollutant and offer some suggestions on how they can reduce their air pollution exposure risks.

While air pollution is the world’s largest environmental health risk, the Director of HKUST Institute for the Environment and PRAISE-HK’s Principal Investigator explained that while Hong Kong’s air quality has improved a lot in recent years, there are still times and places where the air quality is not good. Initially, users may not have had sufficiently detailed data to inform their daily decision-making. But now, PRAISE-HK-EXP provides data and clues to answer various practical questions like, “What is the best time to go for a run? What can I do in my apartment or office to reduce my exposure to unhealthy air? Will opening that window at this hour let in a breeze of fresh air or fill in the room with a dangerous dose of particulate matter?”


PRAISE-HK stands for “Personalised Real-time Air-quality Informatics System for Exposure – Hong Kong”. It aims to empower the public with personalised real-time air quality information and to help build Hong Kong into a world-class smart and healthy city.

It differs from Hong Kong’s official air quality monitoring network (with 18 fixed-site stations) which is designed to measure the average air quality over different districts. PRAISE-HK project aims to provide fine-scale air quality variations between streets as well as personal air pollution exposure details which are highly associated with the time a person spent in each micro-environments in their daily routines.

As a personalised air pollution exposure tracking app, PRAISE-HK-EXP tells users where they contact air pollution from the most and then helps them make decisions about their daily activity that can best protect their health.

The PRAISE-HK-EXP App is developed by cross-disciplinary experts led by the HKUST Institute for the Environment. The highly detailed and accurate performance is attributed to the following important technologies:

  1. Air quality and atmospheric model – analyses and forecasts air quality allowing for dispersion of emissions released both regionally and in Hong Kong, and the associated complex photochemical reactions; and the influence on local pollutant dispersion of urban morphology in terms of building density and street ‘canyons’. The system generates street-scale resolution forecast maps (down to 2-20 metres) that highlight both pollution hotspots and areas of better air quality; a fusion of modelled and measured concentration data ensures forecast accuracy.
  2. Traffic model– informs users of important road-side emission data from more than 30,000 road segments. The team developed a state-of-the-art microscopic activity-based traffic model, the first of its kind for Hong Kong, which captures the daily activity patterns of 4-million agents to derive the underlying traffic patterns across all modes of public transport as well as private car usage. The model produces detailed dynamic traffic patterns which are then used to estimate roadside emissions
  3. Sensor technologies and air quality characterisation by microenvironments– compact and portable sensors have been developed to reach the competent performance goals, and to fit the need for complicated microenvironment monitoring; numerous air quality measurement work has been done to characterise the relationships between indoor and outdoor concentrations for different pollutants, in different microenvironments (e.g. homes, schools, offices, shopping malls and different transport modes) under different ventilation conditions.
  4. Big data– fill a wide range of data gaps (from changing traffic speeds to special traffic incidents) to improve overall accuracy and to raise real-time performances
  5. Air quality exposure science– evaluates personal exposure profiles and associated health impacts
  6. Mobile technology– identifies users’ location either outdoor or indoor, in what kinds of buildings or transportation modes, so that the PRAISE-HK system could analyse its personal exposure to the surrounding air quality.
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