As Hong Kong grapples with the intensifying effects of climate change, a prominent non-governmental organization is calling for urgent government intervention to address the city’s deteriorating air quality during periods of extreme heat. The plea comes as the territory faces a challenging summer, with meteorologists and environmental advocates pointing toward a critical nexus between rising temperatures and the formation of hazardous ground-level ozone.
The core of the concern lies in the atmospheric chemistry of tropospheric ozone, a secondary pollutant that poses significant risks to human health. Unlike the protective ozone layer in the upper atmosphere, ground-level ozone is created when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight. This photochemical process is significantly accelerated by the high temperatures often seen in Hong Kong during the summer months, leading to the formation of harmful smog that can inflame lung tissue and exacerbate respiratory conditions.
A heatwave in Hong Kong in late May 2026. Photo: Kyle Lam/HKFP.
According to the Environmental Protection Department (EPD), ground-level ozone is one of the seven major air pollutants regulated under the Air Pollution Control Ordinance and the city’s established Air Quality Objectives. These objectives set legally binding concentration limits and dictate the number of allowed exceedances per year. However, environmental advocates argue that current regulatory frameworks require stricter oversight of ozone precursors to mitigate the risks posed by increasingly frequent heatwaves.
Environmental groups have emphasized that the public’s health is increasingly vulnerable to the dual pressures of extreme heat and diminished air quality. Research indicates that the emission sources of these ozone precursors are diverse; while nitrogen oxides are largely generated by combustion processes—including electricity generation, road transport, and navigation—volatile organic compounds often stem from non-combustion sources, such as paints, adhesives, sealants, and various consumer products.
The call for policy adjustment highlights the need for a targeted approach to managing VOC emissions, which are critical components in the formation of ground-level ozone. Experts suggest that as global temperatures continue to rise, the frequency of “high risk” air quality days—periods where pollutant concentrations reach levels that may trigger respiratory symptoms or long-term cardiovascular issues—is expected to grow, necessitating more robust environmental management strategies.
Addressing Urban Heat and Air Quality
Beyond emission controls, there is a growing consensus on the importance of urban planning as a tool for public health. The push for “cooling measures” in the city’s most affected districts—such as Tuen Mun, Tai Po, the North District, Yuen Long, and Tung Chung—reflects a broader effort to mitigate the “urban heat island” effect. Proposed strategies include increasing urban greenery, the revitalization of local waterways, and the implementation of ventilation corridor designs intended to improve airflow and reduce trapped heat at the street level.
Air pollution in Hong Kong. File Photo: GovHK.
The government continues to monitor these environmental factors through a network of air quality monitoring stations. The EPD regularly publishes data on air quality and provides updates on environmental initiatives, such as the recent launch of educational programs for Environment Day and the ongoing management of industrial emission sources, including the scheduled cessation of operations for certain concrete batching plants.
The Road Ahead: Monitoring and Regulation
For residents and policymakers alike, the coming months remain a period of high vigilance. The Hong Kong Observatory provides regular weather forecasts, which are essential for identifying the timing of heatwaves that could potentially correlate with spikes in air pollution. Residents are encouraged to monitor the official Air Quality Health Index (AQHI) regularly, which provides real-time data on air quality and associated health risks, allowing for informed decisions regarding outdoor activities during periods of high pollution.
While the city has made strides in diversifying its energy mix away from coal toward natural gas and tightening emission standards for fuel-powered vehicles, the challenge of ground-level ozone remains a persistent hurdle. As the government continues to evaluate its environmental policies, the focus is likely to remain on balancing the city’s economic activities with the imperative of protecting public health against the backdrop of a warming climate.
The Environmental Protection Department continues to provide updates on air quality, beach water quality, and prosecution statistics related to environmental regulations. Members of the public can stay informed by visiting the official Environmental Protection Department news portal for the latest advisories and regulatory updates.
We invite our readers to share their thoughts on how urban planning and environmental policy can better protect public health in the face of changing climate conditions. Please join the conversation in the comments section below.