For Information

Provisional Legislative Council
Panel on Environmental Affairs

Air Pollution Caused by Motor Vehicles and Construction Activities and the Control Programmes


This paper presents an overview of Hong Kong's air pollution problems, particularly those caused by motor vehicles and construction activities, and briefs members of the corresponding control programmes being implemented and planned.


2.Hong Kong's air quality is typical of a major city. Comparisons of Hong Kong's air quality with other major cities in the world are summarised in Table 1. Overall speaking Hong Kong's level of carbon monoxide is very low and the level of respirable suspended particulates is relatively high amongst the world cities. The levels of other air pollutants are somewhat in the middle.

3.We have established a set of Air Quality Objectives (AQOs) which basically act as our benchmarks for Hong Kong's air quality. These AQOs were promulgated in 1987 under the Air Pollution Control Ordinance by making reference to the air quality standards, guidelines and findings of the US EPA, the World Health Organisation and other developed countries. After being in use for 10 years, we are currently reviewing these AQOs as against the recent findings and information concerning health impact of air pollution. We may seek to revise some of the AQOs as a result of the review.

4.Table 2 summarises the status of compliance with the current AQOs. The table shows that the current major air pollution issues are associated with the high concentrations of particulates, nitrogen dioxide and, to a lesser extent, ozone.

5.Motor vehicles, particularly diesel vehicles, are the major sources of the respirable suspended particulates and nitrogen oxides. Analyses have shown that diesel vehicles are likely to be emitting half of the respirable suspended particulates in the urban areas. Although ozone is not emitted directly from motor vehicles, it is formed in the atmosphere mainly by reactions between nitrogen oxides and hydrocarbons emitted from motor vehicles. Construction activities are also emitting much dust and particulates, especially for the portion of particles of relatively larger size.


6.To control the air pollution emissions from motor vehicles, we are implementing an integrated vehicle emission control strategy comprising the following key elements:

  1. clean alternative to diesel vehicles;

  2. stringent vehicle emissions and fuel standards;

  3. strengthened emission inspection;

  4. strengthened enforcement against smoky vehicles; and

  5. education and publicity.

Clean Alternatives to Diesel Vehicles

7.As diesel vehicles are emitting half of the respirable suspended particulates in the urban area, one important facet of the strategy is to reduce the number of diesel vehicles by replacing part of them with cleaner fuel alternatives. In September 1995, we put forward a proposal to replace the light duty diesel vehicle fleet with clean unleaded petrol vehicles. The proposal subsequently met with strong opposition from the transport trade and the then legislature. To consider other alternatives, we set up an inter-departmental working group in September 1996 to explore the feasibility of gas vehicles. The working group has found that liquefied petroleum gas (LPG) vehicle is a practicable clean alternative. To address the concerns by the transport trade as well as to collect local operational information relating to such things as costs and maintenance requirements, a trial of LPG taxis is being planned to start in November 1997 as a pilot scheme. If the trial is successful, a proposal will be made to introduce LPG taxis on a wide scale which will reduce the emission of respirable suspended particulates from the motor vehicle fleet by up to 30%.

8.Apart from LPG taxis, we are also exploring the feasibility of other LPG vehicles such as vans and buses. Moreover, we are monitoring closely the development of other clean alternative vehicles such as electric vehicles. Once these clean vehicles become commercially viable, we will seek to introduce them into Hong Kong.

Stringent Vehicle Emissions and Fuel Standards

9.It is our established policy to adopt the most stringent vehicle fuel and emission standards which are practical and available to Hong Kong. Under this policy, we have progressively tightened up our fuel and emission standards for both petrol and diesel vehicles since 1991. Today, our standards are at the same level as the European Community. Major steps taken in the past years include:

  1. 1991 - The introduction of unleaded petrol;

  2. 1992 -The requirement of 3 way catalytic convertor for new petrol vehicles which will reduce the emission of carbon monoxide, nitrogen oxides and hydrocarbons from individual cars by up to 90%;

  3. 1995 - The introduction of clean diesel with 0.2% sulphur content plus requiring new diesel vehicles to comply with emission standards equivalent to the European Euro I and Euro Phase I standards for heavy duty and light duty vehicles respectively; and

  4. 1997 - The further reduction of sulphur content in motor diesel fuel to 0.05% and requiring new heavy duty diesel vehicles to comply with emission standards equivalent to the new European Euro II standards.

10.Today, over 80% of the petrol consumed in Hong Kong is unleaded. Moreover, 60% of the petrol cars are fitted with catalytic convertors. In terms of emission from diesel vehicles, as compared to the pre-1995 position, the new standards will reduce the emission of sulphur dioxide, RSP and nitrogen oxides from individual diesel vehicles by 90%, 80% and 20% respectively. We shall further tighten our motor fuel and emission standards as and when they are practical.

11.Despite all these stringent standards, because of our extremely high density of motor vehicles and the high diesel mileage, we still need additional control measures to achieve our AQO targets and that is why we are putting forward the LPG taxi trial and looking at cleaner alternatives for other diesel vehicles.

Strengthened Emission Inspection

12.At present, all in-service commercial diesel vehicles undergo a free-acceleration smoke test during their annual road worthiness inspection. To encourage vehicle owners to pay more attention to vehicle smoke emissions, we are working to strengthen the inspection by including smoke measurements using smoke meters, and a check on engine settings and air filters. This more thorough emission check will be initially applied on a sampling basis starting in October 1997. Subject to a review of its effectiveness, we will make the emission check a standard feature of annual inspection, and will examine whether an additional mid-year emission check for high mileage vehicles is appropriate.

Strengthened Enforcement Against Smoky Vehicles

13.The Environmental Protection Department is implementing a smoky vehicle control programme which is calling in 30,000 vehicles a year for smoke tests. In addition, the Police are issuing 2500 fixed penalty tickets a year to those vehicles that are found to be smoky. These programmes have achieved some success in reducing the number of smoky vehicles. However, the general standard of vehicle maintenance for smoke control is still unsatisfactory, and there are still a number of habitual offenders. To improve the general maintenance standard, we are experimenting with the use of a new technology, chassis dynamometers, to test the smoke emission of a vehicle. This new technology, if found to be successful, will help to measure smoke emission more accurately and, much more importantly, will raise the maintenance standards of motor vehicles as a vehicle can pass the test only if it is fully maintained and well tuned. Our target is to introduce the new test to all light duty smoky vehicles by late 1998 and eventually extend it to all smoky vehicles.

14.To step up the deterrent effect, and in response to public concerns, we are also considering increasing the level of fixed penalty fines for smoky vehicles as well as examining mechanisms to strengthen the enforcement arrangements and will consult Members and the transport trades in due course.

Education and Publicity

15.At present, the Environmental Protection Department distributes an information leaflet on measures to prevent excessive smoke emissions to owners whose vehicles have been spotted emitting excessive smoke. We are reviewing the information leaflet and will widen its circulation to other motorists through the transport trade associations. Moreover, to help vehicle buyers to take environmental performance into consideration in choosing vehicles, and to promote cleaner vehicles being marketed by vehicle dealers, we are working out with the Motor Traders Association a scheme to provide motorists with information on the fuel consumption and emission levels of various vehicle models on the market.

Emission from Idling Vehicles

16.In terms of their contribution to the overall air quality, emissions from idling vehicles are not a major source. However, these emissions frequently cause a nuisance to pedestrians and people nearby and therefore have attracted much concern by the community. We have started a publicity campaign in March 1997 to invite drivers to switch off engines while idling and waiting. The publicity campaign includes TV and radio promotion, posters and leaflets. We have also offered support to other non-government organisations to educate the public and the drivers. In parallel, we are collecting information from overseas authorities on regulatory controls on idling vehicles and their enforcement. We are consulting relevant bodies about the practicability of introducing legislative control on idling vehicles in Hong Kong.


17.Construction dust not only raises the level of particulates in the atmosphere but also frequently causes nuisances to people nearby. In 1996 the Environmental Protection Department received 364 complaints against dust emitted from construction activities. The Air Pollution Control Ordinance has a provision to empower officers of the department to issue a notice to owners of the concerned construction sites to abate the nuisances so caused. However this provision mainly serves as a corrective measure and obviously has its limitations in preventing problems and reducing the overall dust emission from construction activities.

18. In June 1997, the Air Pollution Control (Construction Dust) Regulation came into effect. The Regulation specifies the dust control measures that have to be implemented in the course of construction activities. For individual construction activities, these measures can reduce dust emissions by up to 80%. To cater for works already contracted for before the Regulation came into effect, the concerned works and construction sites have been exempted from the requirements for a year. Furthermore, in response to the trades' concerns for the possible difficulties for minor road works to comply with the requirements, we have allowed a 6-month tune-in period for the trade to familiarize themselves with the requirements of the Regulation. To help the trade to understand the requirements, we have organised a seminar and distributed educational pamphlets to all the contractors. During the first two months of implementation, we have made about 200 inspections. During this initial period, most of the construction sites are still exempted from the requirements and hence only 20% of the sites have been observed to have fully taken up the measures, mostly on a voluntary basis. This rate should pick up rapidly when the exemption approaches expiration. We are monitoring closely the operation of the Regulation and the enforcement arrangements.

Environmental Protection Department
September 1997

Table 1

Comparison of Air Quality of Major Cities

Atlanta951036294 335726
Auckland95322 21
Barcelona942151 21279[4]12482
Berlin951726265 509963
Boston951858236 264581
Brisbane95821721 5980
Chicago952460275 395726
Detroit95 2941275 428016
Guangzhou955751[1] 296[2]149[4]14410
Helsinki941046 337443
Hong Kong952057 275[3]602420
Houston951649 393425726
Kuala Lumpur961567 7456
London961572220 2513513
Los Angeles951073 4123913742
Macau95247 58
Manila93 60 87
Mexico City9476250 61223923017
Montreal941338275 277901
New York953979 255269161
Paris941353281 21[4]
Perth961521202 302721
Philadelphia952660 275756871
Pittsburgh954460 275426871
Prague94 3940293 35[4]4581
Rome941692 22821987
San Francisco95540 236215726
Santiago942175 281108
Seoul936666 50[4]
Shanghai 9532 133[4]
Singapore962732 198331488
Sydney951131 2172110500
Taipei954878351 72
Tokyo942164 180494625
Toronto95954 250227500
Vancouver95941 128183750
Washington DC952449 255236871

[1]Estimated from nitrogen oxides concentration

[2]Short-term measurement results in 1995 reported in the consultative document on environmental protection

[3]Measurement at Sha Lo Wan

[4]Estimated from total suspended particulates concentrations

Table 2

Compliance of Air Quality Objectives in 1996

Status of Compliance
% of
AQO at

Hourly300111 Occasional breaches
Daily150115Occasional breaches
Annual8094Marginal compliance

Carbon Monoxide Hourly

Annual55140 Chronic breaches in
4 of the 9 stations

Daily260112 Frequent
Mong Kok
Annual80178 Chronic
in 6 of
the 9 stations

OzoneHourly240131Most of the time at low levels. A few occasional breaches at clam and stagnant weather conditions

LeadQuarterly1.511 Good