In order to further safeguard public health from roadside air pollution, NGO Clean Air Network urged the Chief Executive of HKSAR government to sustain the effort to tackle air pollution, and set up measurable air pollution reduction target for the Transport and Housing Bureau to deliver, as one of the top policy priorities.

Albeit with improvement of key air pollutants over the past few years, Hong Kong’s public health is still under threat from unhealthy air pollution at roadside – about 5 lives are taken per day due to air pollution. CAN worried, if there is no target-driven transport policy aiming to safeguard public health, by 2020, our air quality at the roadside will still be worse than Hong Kong’s Air Quality Objective and the safe level recommended by World Health Organization, by over 60%. Deaths caused by respiratory and circulatory diseases will be increasingly uncontainable.

Districts in the western part of Hong Kong such as Sham Shui Po, Kwai Tsing and Kwun Tong, with dense population, heavily deprived, high traffic density and high level of pollution, require immediate attention. 21% of Hong Kong population reside in these 3 districts and are exposed to constantly severe health risk.

Relationship between changes in air pollutant concentration and health risks

1)       Although the major air pollutants have seen a 30% decrease in the past 5 years, among which NO(nitrogen dioxide) has a relatively slow fall with 8% drop. Compared with 2016 annual figure, the NOlevel in first half of 2017 even marked a 2% increase. On the contrary, deaths caused by the air-pollution-related respiratory and circulatory diseases have risen to over 20,000 respectively in 2015. Being the second common killer after cancer, the figure makes up to 40% of annual registered deaths.

2)       Air pollution is a crucial environmental health risk, which should be given the top priority in non-communicable disease control strategy by Food and Health Bureau. Exposure to roadside pollution accumulates the health risk with age and lead to respiratory and circulatory diseases gradually.

With the reference to World Health Organisation (WHO) researches and various studies by air pollution and public health experts, it’s found that chances for emergency hospital admissions due to respiratory and circulatory diseases rise by 0.75% and 1%, and short-term mortality rate rises by 1.03%, with every 10 µg/mrise in NO2 concentration. For communities with long-term exposure to high level of NO2, such as those living by roads, the long-term mortality rate rises by 3.9% with every 10 µg/mrise in annual NO2 concentration.

3)       Hong Kong, densely populated and subject to street canyon effect, has been long suffering the roadside pollution level double of WHO standard. According to a study conducted by Hong Kong University of Science and Technology, the number of deaths in Hong Kong caused by roadside pollution ranks the highest among the 11 cities in the PRD region, amounting to 773 and 361 premature deaths due to respiratory diseases and lung cancer[1].

Three key environmental risk factors leading to public health crisis

According to Department of Health’s strategic framework document on prevention and control of non-communicable diseases(NCD) in Hong Kong, the risks of developing non-communicable diseases, including respiratory and circulatory diseases, accumulate with age and are influenced by factors acting at all stages of life, one of which being environmental determinants[2]. The three environmental risk factors, namely high roadside pollution level, high social deprivation index (SDI) and high traffic density, further accumulate health risks and threaten public health.

According to the 2016 figures from Census and Statistics Department, high-SDI districts are clustered in the western part of Kowloon and New Territories such as Sham Shui Po, Kwai Tsing and Tuen Mun, considering the median household income level, the number of <15 and >65 populations living in the low-income household. With the proved positive correlation between SDI and air-pollution-related mortality rate, the mortality rate for respiratory and circulatory diseases was 0.12-2.74% higher in those high-SDI districts[3].

CAN reviews the NO2 concentrations across general monitoring stations in the first half of 2017, and discovers that the average NO2level in the western part of Hong Kong is 50 µg/m3, as compared with 39 µg/min the eastern part of Hong Kong. Among all the general monitoring stations, Sham Shui Po, Kwai Tsing and Tuen Mun, which score high SDI, rank the first, second and fourth in the NO2measurements. It reflects that high-SDI districts often correlate with high pollution level.

CAN conducted an on-site NO2 measurement at 5 primary schools located near highway in West Kowloon’s districts with high SDI on 30th June and 7th July. The NO2 concentration ranges from 76 to 125 µg/m3, which illustrates the high health risks by children living in the districts.

Figure 1: CAN conducted on-site NO2 measurement at 5 primary schools located near highway in West Kowloon’s districts with high SDI on 30th June (top) and 7th July (below). The NO2 concentration ranges from 76 to 125 µg/m3.

A recent study shows the traffic density, air pollution and the respective mortality rate are all positively correlated[4]. First, the coefficient ratio of NO& RSP to traffic density is 0.72 and 0.78 respectively.  Second, the excess risk of mortality for circulatory and respiratory diseases is 45% and 59% higher in districts with higher traffic density.

 

Air Pollutant Coefficient ratio to traffic density (1 is the maximum)
NO2 0.72
RSP 0.78

Table 1 – The coefficient ratio of major air pollutants to traffic density

 

Traffic Density Excess Risk of Mortality for Circulatory Diseases Excess Risk of Mortality for Respiratory Diseases
High +45% +59%
Medium +37% +51%
Low (Baseline) 0% 0%

Table 2 – Excess risks of mortality for air-pollution-related diseases with different levels of traffic density

The traffic density in Kowloon West is higher, accompanied by the high SDI and high roadside pollution level. With the three unfavourable environmental risk factors, residents in Kowloon west are faced with accumulating and accelerating health risks. (refer to the graph below)

Figure 2: The accumulated health risks caused by high air pollution, SDI and traffic density would lead to onset of pollution-related diseases later in life[5] (Department of Health, 2008)

Conclusion – Chief Executive should set a roadside pollution reduction target for Transport and Housing Bureau

 No doubt roadside pollution is a public health crisis. Hong Kong takes its own geographical feature, with high concentrated roadside pollution, high SDI as well as high traffic density, which shroud the population in the health threats posed by air pollution. The most seriously polluted districts, namely Sham Shui Po, Kwai Tsing and Kwun Tong, already accommodate 21% of Hong Kong population. This is Chief Executive’s duty to address and solve the above three environmental risk factors, otherwise deaths caused by respiratory and circulatory diseases will be increasingly uncontainable.

CAN considers that the above public health crisis can only be solved by CE’s determination to set a reduction target in roadside air pollutants for Transport and Housing Bureau. According to Clean Air Plan for Hong Kong 2013-2017 Progress Report, Environment Bureau expects the achievable level of NOto be still 62.5% above the AQO by 2020 despite all its possible measures. The ‘unachievable’ gap is ought to be targeted by Transport and Housing Bureau in its capacity of transport management policies.

CAN urges the new administration of HKSAR government to adopt a public health approach to transport and environmental management, by

1) establishing air pollution reduction target for Transport and Housing Bureau to deliver;

2) delegating Environment Bureau to continue implementing and monitoring emission control measures;

3) delegating Food and Health Bureau to devise action plan to lower the health risks of non-communicable diseases posed by air pollution.

Only when measurable targets are clearly specified and set, our public health will be sufficiently safeguarded.


[1] Lu, X., Yao, T., Li, Y., Fung, J. C., & Lau, A. K. (2016). Source apportionment and health effect of NO x over the Pearl River Delta region in southern China. Environmental Pollution, 212, 135-146.

[2] HKSAR Department of Health. (2008). Promoting Health in Hong Kong: A Strategic Framework for Prevention and Control of Non-communicable Diseases.

[3] Wong, C. M., Ou, C. Q., Chan, K. P., Chau, Y. K., Thach, T. Q., Yang, L., … & Hedley, A. J. (2008). The effects of air pollution on mortality in socially deprived urban areas in Hong Kong, China. Environmental Health Perspectives, 116(9), 1189.

[4] Ma, X. [馬曉楠]. (2014). Traffic-related exposures and all-cause and cause-specific mortality of general and older population in Hong Kong. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5194760

[5] HKSAR Department of Health. (2008). Promoting Health in Hong Kong: A Strategic Framework for Prevention and Control of Non-communicable Diseases.

Story posted on
14th Jul, 2017

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