Atmosphere, Ocean and Air-Quality Research — Serving the Environment of the Greater Bay Area

Hong Kong and the Pearl River Delta form one of the most densely populated and economically dynamic regions on earth — and they pay for it with severe air pollution and intense pressure on water quality. Building on its strengths in Earth, atmospheric and marine science, HKUST has become a major force in environmental research for Hong Kong and the Greater Bay Area. This article focuses on the University's role in air-quality research, regional ozone and pollution studies in the Pearl River Estuary, complementing the pieces on key laboratories and institutes (Part 1)^※ (which covers the coastal-city climate resilience lab) and the Science Faculty deep dive^※ (which covers the Department of Ocean Science).

In one sentence: HKUST's environmental research is no ivory-tower exercise. From ground-level supersites and street-by-street mobile apps, to water-quality buoys in the Pearl River Estuary and land–sea–air ozone observation campaigns, it is embedded directly in the environmental governance systems of Hong Kong and the Greater Bay Area.

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# 1. The Air Quality Research Supersite

One of the signature facilities of HKUST's air-quality work is its Air Quality Research Supersite. According to the University, HKUST launched Hong Kong's first air-quality research supersite to strengthen air-quality research and tackle air-pollution problems in Hong Kong and the Pearl River Delta^※.

"Supersite" is an internationally recognised term, described by HKUST as a highly specialised, well-instrumented air-monitoring facility that uses state-of-the-art instruments to carry out integrated, comprehensive air-quality measurements^※. The supersite was established with funding from the University Grants Committee (UGC) and the Environment and Conservation Fund, and characterises airborne particulate matter (PM) in real time to deepen understanding of the properties and sources of fine particles^※.

That "real-time characterisation of fine particles" is the crux of the matter: before you can clean up air pollution, you have to know what the pollutants are and where they come from. The supersite lets researchers analyse the chemical composition and sources of PM2.5 and other fine particles in real time, giving pollution-control efforts a scientific foundation. Traditional air monitoring is mostly about measuring concentrations — it tells you how bad the pollution is. The supersite goes further, identifying the composition, answering whether the pollution is dominated by sulphates, nitrates, organic carbon, elemental carbon or sea salt, and thereby pointing the finger at the real emission sources: local vehicle exhaust, coal-fired power plants, or regional pollution blown in from the upwind Pearl River Delta. For a pollution problem that is cross-border, multi-source and chemically complex, this source-apportionment capability is precisely the scientific threshold that separates treating the symptom from treating the cause.

It is worth noting that supersites of this kind are usually run by national environmental agencies or large research programmes elsewhere in the world. That a single university built and operates the first such facility in Hong Kong says a great deal about the calibre of HKUST's instrumentation and expertise in atmospheric chemistry. The supersite is not just a piece of equipment; it is a research platform that continuously produces high-quality composition data, supporting long-term trend analysis and policy evaluation — and laying the groundwork for the University's decade-long role supplying PM2.5 data to the Environmental Protection Department, discussed below.

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# 2. The Institute for the Environment and the Division of Environment and Sustainability: where the enterprise is institutionalised

Behind the scale of HKUST's environmental research sits a stable institutional structure. The two hubs are the Institute for the Environment (IENV) and the Division of Environment and Sustainability (ENVR) — the former an interdisciplinary research platform, the latter responsible for teaching and degree programmes in environment-related fields. The two work as two sides of the same coin, rallying the atmospheric, ocean, civil and environmental engineering strengths scattered across the Schools of Science and Engineering under a single banner.

One of the leading figures in this structure is Prof. Alexis Lau. According to HKUST's profile page for him^※, he serves concurrently as Head and Chair Professor of the Division of Environment and Sustainability, Chair Professor of Civil and Environmental Engineering, Director of the Institute for the Environment, and the Tang Junyuan Professor of Environmental Science. He earned his PhD in Atmospheric and Oceanic Sciences from Princeton University, has published over 200 journal papers, led more than 100 research projects as principal investigator, and secured more than HK$230 million in research funding^※. One detail is quietly telling: his doctoral alma mater, Princeton, is the ancestral home of the "institute for advanced study" model that HKUST's own Jockey Club Institute for Advanced Study^※ emulates — HKUST's environmental science, in other words, is connected by lineage to one of the world's great scholarly traditions.

The Institute for the Environment's mission is to link "measurement — analysis — modelling — policy" into one continuous chain. It conducts fundamental atmospheric chemistry and marine biogeochemistry, but also policy-facing exposure science and health-risk assessment; it serves academic publication, but also speaks directly to the governance needs of the Hong Kong SAR government. The PM2.5 data supply, the AQHI health index, the PRAISE-HK mobile app and the regional ozone research described below all unfold within this framework. If the supersite is the flagship hardware of HKUST's environmental research, the Institute for the Environment and the Division of Environment and Sustainability are the operating system that keeps it running.

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# 3. Supplying data to the EPD's PM2.5 monitoring network (since 2011)

The reach of HKUST's environmental research extends beyond academia into the fabric of Hong Kong's environmental governance. According to HKUST's research-impact case studies, the government's Environmental Protection Department has relied on the University since 2011 to provide analytical data for its PM2.5 monitoring network^※.

The significance is hard to overstate: HKUST does not merely study air pollution — it has become one of the analytical mainstays of Hong Kong's official PM2.5 monitoring system. HKUST states that it possesses the most comprehensive capability in Hong Kong and the Pearl River Delta region to advance knowledge of air quality, spanning measurement, chemical and physical analysis, modelling, control approaches, and impact and policy studies^※. This end-to-end capability — from "measurement" to "policy research" — casts the University in the role of a research think-tank for regional air-quality governance.

From a contract to a scholar. Behind this data chain stands an atmospheric chemist who has spent decades at HKUST: Prof. Jianzhen Yu. According to HKUST's research-impact page, she joined HKUST in 1999^※, and her group has built internationally recognised methodological expertise in the atmospheric measurement of particulate composition. Yu's contribution is not merely running samples; she has developed analytical techniques adopted by colleagues around the world. HKUST credits her with pioneering work on the pyrolysis effect in thermal–optical transmittance carbon analysis, and on an in-port thermal desorption gas chromatography–mass spectrometry (GC-MS) method for non-polar organic compounds^※, the latter eliminating lengthy sample-preparation steps and establishing conversion relationships that allow results from different measurement protocols to be compared — vital for data comparability across cities and across years.

Numbers speak. This long-running monitoring programme has quantified Hong Kong's air-quality improvement. At six monitoring sites, annual mean PM2.5 concentrations fell from 31.3–43.1 micrograms per cubic metre in 2011 to 18.7–27.2 micrograms per cubic metre in 2017^※ — a drop of roughly 30–40 per cent in five or six years. This is not an abstract claim that "the air has got better"; it is a verifiable data curve.

How research becomes policy. The Environmental Protection Department has stated explicitly that Yu's research provided the scientific basis for its decision-making on environmental issues^※. HKUST links this scientific support to the Diesel Commercial Vehicle Replacement Scheme (2014–2019), which targeted some 82,000 vehicles^※. In other words, policy judgements about which pollution sources to prioritise are underpinned on the composition analysis HKUST provides. Yu's group has also exported its capability across the region: HKUST reports that it completed the first comprehensive PM2.5 composition survey in Macau (2015) and led collaborative projects across Guangdong, Hong Kong and Macau^※, with cumulative government and institutional funding exceeding HK$16.8 million.

This data chain, running "since 2011", is itself a textbook example of a research university serving society — not a one-off consultancy report, but an unbroken decade-plus of service as the analytical backbone of an official monitoring system. Yu's group's expertise has even travelled to the Yangtze River Delta: HKUST notes that it collaborated with the Shanghai Academy of Environmental Sciences to study air quality in the Yangtze River Delta^※, carrying the source-apportionment methods honed in the Pearl River Delta to another major city cluster.

Embedded in a cross-border monitoring network. HKUST's analytical capability does not operate in isolation; it sits inside a larger framework of joint regional governance. As early as November 2005, the Guangdong and Hong Kong governments established the Pearl River Delta Regional Air Quality Monitoring Network (PRD RAQMN), the first joint regional air-pollution monitoring and reporting mechanism in this fast-developing, heavily polluted part of southern China^※. According to a Hong Kong government press release, the Guangdong–Hong Kong–Macau network comprises 23 air monitoring stations, and has included carbon monoxide (CO) and fine suspended particulates (FSP) in its measurements since September 2014^※. Comparing the long-term trend from 2006 to 2021, the picture is one of real progress alongside new challenges:

This table also explains why HKUST's research firepower has shifted in recent years from particulates to ozone (see Section 5 below): when conventional pollutants are falling across the board and only ozone is rising, the "main battlefield" of regional pollution control is quietly moving.

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# 4. The Air Quality Health Index and PRAISE-HK: taking research to the street

A second thread running through HKUST's environmental work is translating "air data from the laboratory" into "health information ordinary people can use". This is a story of evolution from policy tool to consumer app.

2013: the arrival of the AQHI. According to HKUST's profile of him, Prof. Alexis Lau helped drive the introduction of the Air Quality Health Index (AQHI) in 2013, making Hong Kong a pioneer in health-based air-quality management^※. The key shift embodied by the AQHI is that it no longer simply reports "pollutant concentrations"; it answers a far more personal question: "How much does today's air raise my risk of hospitalisation or respiratory discomfort?" This pulls air monitoring down from the scale of environmental indicators to the scale of individual health.

2015–2018: the first Pan-Pearl River Delta PM2.5 study. HKUST records that Lau led the first Pan-Pearl River Delta PM2.5 study (2015–2018), a joint initiative of the Hong Kong, Guangdong and Macau governments^※. Cross-border joint research is the inevitable answer to the reality that "pollution respects no borders".

From 2019: PRAISE-HK sharpens the AQHI to street-corner resolution. If the AQHI gives "one number for the whole city", PRAISE-HK gives "one number for every street". According to HKUST, the smart-city mobile app named PRAISE-HK, launched on 21 June 2019, provides real-time and forecast (up to 48 hours ahead) street-level air-quality and health-risk information at a spatial resolution as fine as 2 to 20 metres^※. Led by Lau, it is a five-year project that began in November 2016, funded under the HSBC 150th Anniversary Charity Programme^※.

The app displays more than the AQHI: it also shows the additional short-term health risk percentage (%AR) — the increased risk of hospital admission on a given day attributable to pollutants including nitrogen dioxide, ozone, respirable suspended particulates (PM10 and PM2.5) and sulphur dioxide. It fuses air-quality modelling, traffic analysis, sensor technology, big data, exposure science and mobile technology into a single tool, letting users plan a commute that minimises pollution exposure. Lau's own words capture the app's purpose: 「许多人以为自己对减少污染暴露无能为力。这已经不再成立！」^※ ("Many people think they are powerless to reduce their exposure to pollution. That is no longer true!")

From a map to an exposure budget. PRAISE-HK did not arrive fully formed; it evolved in stages. The first phase (June 2019) offered a street-level outdoor air-quality map; the second (November 2021) added a "cumulative daily air-pollution exposure risk budget" for each user — upgrading "how dirty is this street right now" to "how much pollution have you actually breathed in all day". Public recognition is documented: according to HKUST's Academy of Interdisciplinary Studies, PRAISE-HK received the Gold Award at the Asia Smart App Awards 2022/23^※.

Lau's own role extends well beyond "making an app". HKUST notes that he founded two undergraduate programmes, "Environmental Management and Technology" (EVMT) and "Sustainable and Green Finance" (SGFN)^※, carrying the concerns of environmental research into talent cultivation. He also serves on the Hong Kong SAR government's Advisory Council on the Environment, is a World Meteorological Organization (WMO) expert, and has been President of the Hong Kong Institute of Qualified Environmental Professionals (HKIQEP) since 2015. His appointment as the Tang Junyuan Professor of Environmental Science took effect, HKUST records, on 1 January 2025^※. Taken together, these roles sketch the typical multi-hatted shape of environmental research at HKUST: academic, policy, industry and education at once.

From the AQHI in 2013, to the street-corner precision of PRAISE-HK in 2019, to the "all-day exposure budget" added in 2021, this thread shows a rare "downward" trajectory in HKUST's environmental research — the most advanced exposure science ultimately becoming an icon in an ordinary citizen's pocket. The spirit of this work aligns closely with HKUST's SDG strengths in the THE Impact Rankings^※, particularly the "Sustainable Cities" and "Good Health" goals.

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# 5. Regional ozone in the Greater Bay Area: land, sea and air monitoring (from 2021)

As PM2.5 levels in Hong Kong have fallen year on year, a more intractable opponent has emerged: ozone (O₃). Unlike particulates, ground-level ozone is not emitted directly. It is secondary — formed by photochemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) under sunlight — and it travels readily across borders on air currents. No single city can tackle it alone; it demands regional coordination and three-dimensional observation.

According to HKUST, in August 2021 the University launched with the Hong Kong SAR government a ground-breaking three-year cross-boundary study measuring air quality on land, at sea and in the air simultaneously, to investigate the generation and transport of ozone in Hong Kong and the Greater Bay Area^※. It forms part of the "Study of Photochemical Ozone Formation, Regional and Super-regional Transport Characteristics in the Greater Bay Area", jointly initiated by the Guangdong, Hong Kong and Macau governments.

The most striking feature of the study is its land–sea–air deployment. HKUST reports that the team used ocean-going vessels and helicopters carrying advanced sensors to measure pollutants from ground level up to 600 metres in altitude^※ — expanding the two-dimensional data previously available from ground stations into a three-dimensional picture tracking the vertical distribution and cross-border transport of pollutants. The study is led by the Environmental Protection Department, with the Government Flying Service providing the aerial platform; the HKUST team is drawn from the Division of Environment and Sustainability, including Zhi Ning, Dasa Gu and Zhe Wang. HKUST describes the large-scale cross-boundary study as a major milestone in regional ozone research^※.

The significance of the ozone work is that it moves HKUST's role from "monitoring existing pollution" to "cracking the next pollution problem". PM2.5 control has borne fruit; ozone is now the new bottleneck on Greater Bay Area air quality. Whoever first works out the mechanisms of ozone formation and the pathways of its cross-border transport holds the scientific initiative for the next phase of regional pollution control. The HKUST-FYBB#1 satellite^※, used for environmental and disaster monitoring, complements this ground–sea–air observation campaign at the remote-sensing level — together they sketch HKUST's observational spectrum "from low Earth orbit to the street corner".

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# 6. Pearl River Estuary pollution research: the Jockey Club's HK$18 million

In the water environment, too, HKUST has made major contributions. The Pearl River Delta region has undergone enormous economic and social development — and with it, severe deterioration in water quality. According to HKUST's Environmental Central Facility, the Hong Kong Jockey Club funded HKUST with an HK$18 million research project to conduct a scientific investigation of pollution in the Pearl River Estuary^※.

The Pearl River Estuary is the vital waterway connecting the Greater Bay Area's core cities — Guangzhou, Shenzhen, Hong Kong and Macau. Its water quality bears directly on the regional ecosystem and on the environmental health of tens of millions of people. HKUST's systematic investigation of estuary pollution is an example of its marine-science capability (see the Science Faculty deep dive^※, Department of Ocean Science section) being brought to bear on regional environmental governance needs. It also testifies once again to the Jockey Club's long-standing support for HKUST research (see the pre-history of the University's founding^※).

The Jockey Club's funding of the estuary study continues a pattern of deep and sustained investment in HKUST's research infrastructure — from the 1987 donation that built the Clear Water Bay campus, to naming rights for the Jockey Club Institute for Advanced Study^※, the Club has been present at nearly every pivotal moment of HKUST's research development (for the full story, see Gifts and Naming^※). As for the estuary itself, directing charitable funds towards pollution investigation in a stretch of cross-border water reflects the public weight of the subject: the waters of the Pearl River Estuary are the shared lifeline of four core Greater Bay Area cities.

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# 7. Marine science: eutrophication, hypoxia and "red tides" (OCEAN-HK)

Pearl River Estuary pollution is only one facet of HKUST's marine environmental research. In recent years, the Department of Ocean Science has turned its focus to a stealthier and more menacing problem: hypoxia — seawater oxygen depletion, commonly known as "dead zones".

Start with "red tides". For Hong Kong residents, the most visible consequence of marine eutrophication is the "red tide" — a harmful algal bloom. When nitrogen and phosphorus nutrients in seawater are in excess, algae reproduce explosively in a short period, staining the sea surface reddish-brown. Algal blooms can carry toxins and harm farmed fish; they also consume large amounts of oxygen as they die and decompose, inflicting economic damage on coastal fisheries. The Pearl River Estuary is a red-tide hotspot, the surface manifestation of a eutrophication process decades in the making.

The severity of the problem. The Pearl River carries vast loads of nitrogen and phosphorus into the sea each year; combined with urban sewage discharge, Hong Kong and Pearl River Estuary waters remain chronically eutrophic. Excess nutrients trigger algal blooms (the "red tides"/harmful algal blooms); when the algae die and decompose, the process consumes oxygen en masse, eventually producing water layers with extremely low dissolved oxygen. According to HKUST's School of Science, hypoxia is defined as waters in which dissolved oxygen generally falls below 2 milligrams per litre; it is a consequence of persistent and intensifying eutrophication and may offset the environmental gains achieved by the costly Harbour Area Treatment Scheme of the past decade^※. In other words: Hong Kong may spend heavily to treat direct sewage flows into the harbour, only to have those gains quietly undermined by eutrophication carried down from the Pearl River.

The OCEAN-HK project. To answer this question systematically, HKUST leads a major study called OCEAN-HK (Ocean Circulation, Ecosystem and HypoxiA arouNd Hong Kong waters), headed by Prof. Jianping Gan, Head of the Department of Ocean Science, and funded under the University Grants Committee's Theme-based Research Scheme. According to the School of Science, the project aims to identify the factors driving intensifying eutrophication and hypoxia, and to provide analytical tools and science-based strategies to stabilise or even reverse them^※. The research is organised around four tasks: nutrient sources and sinks and their biogeochemical controls; ecosystem dynamics and biological controls; pollutants and ecosystem impacts; and the physical controls and future trends of the "river–estuary–shelf" waters, integrated.

Methodological innovation. School of Science materials describe the team's plan to build a novel, state-of-the-art ocean monitoring system through interdisciplinary spatial mapping and time-series measurements^※ — combining long-term observations from fixed buoys with cruise-based regional mapping to create an unprecedented database of the hydrology, eutrophication and hypoxia of the Pearl River Estuary and Hong Kong waters. This data and the accompanying models serve directly the marine environmental management of Hong Kong's Environmental Protection Department, Observatory and Agriculture, Fisheries and Conservation Department. The project's value lies not merely in "diagnosis" but in "prescription": it explicitly aims to provide science-based strategies that "stabilise or even reverse" eutrophication and hypoxia, bringing fundamental research to bear on concrete marine governance.

A "diagnosis and prognosis" philosophy. The full name of the OCEAN-HK project includes the emphatically medical terms "Diagnosis and Prognosis" — no accident. It treats the ocean as a patient: first diagnose the cause (where the nutrients come from, how they are transported across the river–estuary–shelf continuum), assess the condition (how hypoxia evolves seasonally and interannually), then forecast the trajectory and prescribe interventions. This philosophy of "mechanism first, treatment targeted at the cause" echoes the supersite's source apportionment in the air domain and the ozone study's pursuit of formation mechanisms — it is the methodological bedrock of environmental research at HKUST. For the Department of Ocean Science's structure and wider research directions, see the Science Faculty deep dive^※, Department of Ocean Science section.

From air to seawater, the logic of HKUST's environmental research is consistent: first use data and models to establish what the pollution is, where it comes from and how it evolves; then hand the conclusions to those who govern. Hypoxia research is to the ocean what the supersite's source apportionment is to the air — the scientific step that upgrades "treating the symptom" to "treating the cause".

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# 8. Placing it all in the "serving the Greater Bay Area" narrative

Seen against HKUST's broader story, the significance of its environmental research lies in its embeddedness in place:

1. Problems that come from home. Air pollution, regional ozone, Pearl River Estuary water quality, marine hypoxia — these are the most pressing environmental problems of Hong Kong and the Greater Bay Area. HKUST's environmental research is no abstract academic exercise; it addresses real problems of the land beneath its feet and the sea beside it.
2. Capability embedded in governance. From supplying PM2.5 analysis data to the Environmental Protection Department and putting the AQHI into citizens' phones, to leading cross-border ozone research and investigating estuary pollution and marine hypoxia, HKUST's environmental research capacity is substantively embedded in the regional environmental governance system — a concrete instance of a research university serving society.
3. Full chain and multiple scales. HKUST's strength lies not in any single point but in the full "measurement–analysis–modelling–control–policy" chain, and in cross-scale coverage running from "2-metre street resolution" to "600-metre three-dimensional monitoring" to "low-Earth-orbit remote sensing".
4. Links to climate resilience. HKUST's environmental research connects with its State Key Laboratory of Marine Pollution and the coastal-city climate resilience work^※, its SDG strengths in the THE Impact Rankings^※, and even the HKUST-FYBB#1 satellite^※ used for environmental monitoring — together forming a research cluster that answers environmental challenges with technology.

From the ground-based air-quality supersite to the street-level PRAISE-HK app; from the land–sea–air ozone observation campaign to the water-quality buoys and hypoxia surveys of the Pearl River Estuary; from the low-Earth-orbit environmental monitoring satellite — HKUST's environmental research serves the Greater Bay Area, the land it calls home, in a "sky–land–sea" three-dimensional way.

Note: The facilities (the supersite), collaborations (EPD PM2.5 data supply, the Jockey Club estuary study, the Greater Bay Area ozone study, OCEAN-HK), funding figures (HK$18 million; cumulative funding of HK$230 million; HK$16.8 million) and numerical values (PM2.5 concentrations, 2–20 m resolution, 600 m altitude, 82,000 vehicles) cited here are as recorded on the source pages at the time of writing and are time-sensitive; projects, funding and collaborations evolve continually, and readers should consult the latest official HKUST announcements before citing.

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# Further reading

• Key laboratories and institutes (Part 1) — three State Key Laboratories and the Jockey Club Institute for Advanced Study^※ (including the State Key Laboratory of Marine Pollution and coastal-city climate resilience)
• Science Faculty deep dive^※ (including the Department of Ocean Science)
• Satellites and space — HKUST-FYBB#1 and the constellation ambition^※
• THE Impact Rankings and the SDGs^※

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