Hong Kong’s transport chief has said that late-night aircraft noise over Tung Chung is within acceptable limits in terms of risks to residents’ health.

Lawmaker Chan Hok-fung relayed concerns from residents during a legislative Q&A on Wednesday. He said that the issue “has been aggravated significantly,” since the operating hours of the South Runway were extended to 2am in August last year.

His requests for the utilisation rate of the runway during midnight and 2am were not met by Secretary for Transport and Logistics Mable Chan. However, the minister said that the Airport Authority had conducted health impact assessments with regard to noise.

“The assessment indicates that both short-term and long-term potential health risks resulting from the operation of the 3RS [Three Runway System] are within acceptable levels,” she said.

The Aviation Environmental Federation, a UK-based non-profit, says high levels of aviation noise can lead to chronic sleep disturbance and long-term annoyance.

The World Health Organization (WHO) recommends that the annual average outdoor noise level for aircraft, across 24 hours, remains below 45 decibels. The WHO uses a Day-Evening-Night level metric, taking account of quiet and loud moments throughout a year, whilst penalising night-time noise before averaging them out to a single figure.

In environmental impact assessments, Hong Kong uses the Noise Exposure Forecast (NEF) 25 contour, under which the day-night average sound level of aircraft should be kept at around 55 to 60 decibels.

Hong Kong’s Civil Aviation Department monitors aircraft noise by tracking the peak instantaneous noise level of individual flights passing overhead, rather than a continuous annual average. It then publishes the percentage of total flights which hit certain decibel brackets.

In the 12 months leading up to March 31 this year, 91.49 per cent of flights over Tung Chung emitted noise under 65 decibels – the rest exceeded the limit.

Mitigation measures

The transport chief said on Wednesday that a number of aircraft noise mitigation measures had been rolled out and aviation technology was improving to dampen engine sound.

“Relevant measures include control at source by prohibiting/restricting aircraft with higher noise levels from operating in Hong Kong, and reducing the number of flights overflying densely populated areas at night when weather and safety conditions permit, such as arranging arrival aircraft to land from the southwest over the water, thereby mitigating the noise impact on residents living in the vicinity of the airport,” she said.

“While consolidating and enhancing Hong Kong’s position as an international aviation hub, the Government will continue to balance community well-being and environmental benefits, proactively promoting the synergistic development of the aviation industry and the environment to achieve high-quality and sustainable growth,” she added.

Hongkongers may complain about aircraft noise by contacting the Civil Aviation Department hotline on 2769 6969 or emailing aircraftnoise@cad.gov.hk.

NGO Green Power has urged the Hong Kong government to better regulate ozone precursors as hot weather exacerbates air pollution across the city.

Chemical compounds – such as nitrogen oxides, methane, Volatile Organic Compounds (VOC) and carbon monoxide – form ground-level ozone by reacting in the lower atmosphere in the presence of sunlight. Ground-level ozone attacks and inflames lung tissue, but reducing underlying pollutants prevents harmful smog.

According to a Sunday press release, Green Power’s director, Cheng Luk-ki, said VOCs – which are emitted through oil and gas operations, petrol evaporation and chemical solvents – should be better regulated.

See also: How extreme heat became the deadliest silent killer among world weather disasters

“In the future, the public’s health may be affected by both high temperatures and air quality at the same time,” the press release said.

Last week, Hong Kong sweltered amid a days-long heatwave. Whilst rain brought some respite over the weekend, the Observatory predicts highs of 35 degrees Celsius by the end of this week.

Cooling measures for hottest areas

Green Power’s review of Hong Kong’s air quality situation in 2025 found that 15 air quality monitoring stations recorded “a total of 2,080 hours at High, Very High and Serious levels – collectively referred to as ‘High Risk (HR) hours.'”

See also: How Hong Kong’s elderly face deadly heat inside cramped cage homes

Cheng said Hong Kong was affected by a northern Chinese dust storm last April, pushing up the statistics. However, the NGO also noted that overall air quality has been improving thanks to the city’s diversification away from coal towards natural gas, as well as efforts to tighten emission standards for fuel-powered vehicles.

The director said he had analysed last summer’s Air Quality Health Index data, and found that the nine days ranked as “high risk” all saw temperatures exceeding 29 degrees Celsius, “demonstrating a strong connection between heat and air quality.”

He warned that hot weather will become more frequent, as he urged the authorities to take action in the territory’s hottest districts.

The NGO recommended cooling measures in Tuen Mun, Tai Po, North District, Yuen Long and Tung Chung, “such as increasing greenery coverage, revitalising local rivers, and incorporating more ventilation corridor designs.”

See also: How extreme heat became the deadliest silent killer among world weather disasters

Hong Kong has already warmed by 1.7 degrees Celsius since the Industrial Revolution, research NGO Berkeley Earth says. Heat and humidity may reach lethal levels for protracted periods by the end of the century, according to a 2023 study, making it impossible to stay outdoors in some parts of the world.