LCQ3: Roadside air quality

Hong Kong (HKSAR) -      Following is a question by the Hon Dennis Kwok and a written reply by the Secretary for the Environment, Mr Wong Kam-sing, in the Legislative Council today (February 28):
     Since September 1, 2014, the Environmental Protection Department (EPD) has implemented a new measure to detect, by using roadside remote sensing equipment, petrol and liquefied petroleum gas vehicles with excessive emissions on the road. Where EPD staff have found vehicles with excessive emissions, they will issue emission testing notices to the vehicle owners concerned, demanding them to fix their vehicles and send their vehicles to a vehicle emission testing centre within 12 working days for an emission test with a chassis dynamometer. However, some environmental groups have pointed out that the aforesaid and other air quality improvement measures implemented in recent years by the Government have no significant effect.

The roadside air pollution problem therefore remains serious. It has been reported that the Air Quality Health Indexes recorded at the general and roadside air quality monitoring stations reached 7 or above (i.e. high, very high or serious health risk) for 44 days and 55 days respectively last year, which were nearly 68 per cent and 77 per cent higher than the corresponding figures of 26 days and 31 days in 2016.

In this connection, will the Government inform this Council:
(1) given that EPD conducted a short-term air quality monitoring study from 2013 to 2015 by installing diffusion tubes at 172 locations across the territory where pedestrian and vehicular traffic were heavy or air dispersion conditions were poor to measure the levels of nitrogen dioxide (NO2), of the detailed addresses of such locations and the respective NO2 levels recorded at the various locations; if EPD cannot provide such information, of the reasons for that; and
(2) of the respective numbers of (i) registered vehicles across the territory, (ii) vehicles and (iii) vehicle trips monitored through the use of roadside remote sensing equipment by EPD, as well as (iv) vehicles detected with excessive emissions, in each year since 2014, together with a tabulated breakdown by class of vehicles?
     To improve our air quality and protect public health, the Hong Kong Special Administrative Region (SAR) Government is committed to reducing local air pollutant emissions. In recent years, the SAR Government has undertaken air quality enhancement measures focused on the control of local pollution sources. Key measures include phasing out some 82 000 pre-Euro IV diesel commercial vehicles by the end of 2019; subsidising franchised bus companies to retrofit their eligible Euro II and III buses with selective catalytic reduction devices; strengthening the vehicle emission control regime for petrol and liquefied petroleum gas (LPG) vehicles by using roadside remote sensing equipment; progressively tightening emission caps for power plants; tightening emission standards for newly registered vehicles in phases; setting up the Pilot Green Transport Fund to encourage our transport sectors and non-profit-making organisations to try out innovative green transport technologies; introducing new regulations on statutory emission standards for non-road mobile machinery newly supplied for local use; encouraging walking and the use of public transport, offering first registration tax concessions for buyers of electric vehicles (EVs) and lower vehicle licence fees for EVs, capping the sulphur content of locally supplied marine light diesel at 0.05 per cent; and requiring ocean-going vessels to switch to marine fuel with sulphur content not exceeding 0.5 per cent while at berth in Hong Kong, etc.
     Over the past five years (i.e.

2013-2017), the ambient and roadside concentrations of major air pollutants including Respirable Suspended Particulates, Fine Suspended Particulates (PM2.5), nitrogen dioxide (NO2) and sulphur dioxide have dropped by 26 per cent to 38 per cent, indicating the effectiveness of the control measures implemented in recent years. The SAR Government will continue to take forward emission reduction measures targeting various pollution sources. Such measures include expanding the scope of the control programme for volatile organic compounds (VOC) with effect from January 1, 2018, preparing legislation to require mandatory use of low sulphur fuel by all vessels navigating in Hong Kong waters, etc.

To keep enhancing the air quality in Hong Kong, we will also continue to work closely and proactively with the Guangdong Provincial Government on reducing air pollutant emissions within the region. Collaborations include a joint study on PM2.5 in the Pearl River Delta region conducted by the governments of Guangdong, Hong Kong SAR and Macao, the findings of which can provide solid scientific foundations for formulating strategies to further enhance regional air quality; and the inclusion of VOC monitoring in the Regional Air Quality Monitoring Network in phases from 2018, so as to collect more data related to the formation and movement of ozone within the region, thereby facilitating the formulation of policies and measures to reduce regional ozone concentrations.
     Air quality is affected by both the air pollutant emissions and meteorological factors. Air pollutant emissions are directly related to economic activities and control measures and are the major determinants of the long-term trend of air quality.

On the other hand, fluctuations in meteorological conditions can cause short-term changes in air quality. There could be differences in air quality between years due to changes in meteorological conditions even though the air pollutant emissions remain stable. To assess the overall changes in air quality and the effectiveness of control measures, we should thus observe the long-term trend of air quality rather than its short-term changes.

The Air Quality Health Index (AQHI) mainly reflects short-term changes in air quality and hence is more susceptible to influence by short-term meteorological factors, e.g. sunshine, wind speed, rainfall, etc. Compared with 2016, there were more days in 2017 with meteorological conditions favouring the formation of regional photochemical smog or disfavouring the dispersion of pollutants (e.g.

sunny and windless weather, or influence of outer subsiding air associated with tropical cyclones). As a result, there were more days in 2017 with AQHI at "7" or above.
     My responses to the two specific questions raised by the Hon Dennis Kwok are as follows:
(1) The Environmental Protection Department (EPD) conducted a short-term air quality monitoring study from 2013 to 2015 by installing diffusion tubes (Note 1) at 172 roadside monitoring points across the territory where pedestrian and vehicular traffic were heavy or air dispersion conditions were poor to measure the NO2 levels at these monitoring points. Each measurement period lasted for 21 days.

The purpose of the study was to examine roadside NO2 levels on busy roads in various districts by using simple monitoring equipment, thereby ascertaining whether our existing roadside air quality monitoring stations could reflect the situations at roadsides where air pollution was high. The results of the study showed that the overall NO2 levels measured next to the three existing roadside air quality monitoring stations were higher than the average NO2 level recorded at different types of roadside monitoring points, indicating that the data collected by the existing monitoring stations could reflect the situations at roadsides with high air pollution level (Note 2) (Table 1 in Annex I). Detailed locations of all the monitoring points under the study and the NO2 levels recorded are at Table 2 in Annex I.
(2) Poorly maintained petrol and LPG vehicles could emit pollutants (including carbon monoxide, hydrocarbons and nitrogen oxides) up to 10 times of their normal levels, thereby aggravating roadside air pollution.

To further improve roadside air quality and protect public health, the EPD has been deploying, since September 1, 2014, roadside remote sensing equipment (RRSE) to identify petrol and LPG vehicles emitting excessively, for strengthening the control over them. For any vehicle found to be emitting excessively by the RRSE, we will issue an Emission Testing Notice (ETN) to its owner under section 77B of the Road Traffic Ordinance (Cap. 374). The owner will be required to rectify the excessive emission problem and send the vehicle to a designated vehicle emission testing centre for an emission test with the aid of a chassis dynamometer within 12 working days so as to confirm the rectification of the excessive emission problem.

If the owner fails to send the vehicle to the testing centre or the vehicle fails to pass the emission test, the Transport Department may cancel the licence of the vehicle concerned. From 2014 to 2017, EPD’s RRSE monitored a total of some two million petrol or LPG vehicles. About 10 600 ETNs were issued.

The number of registered vehicles and the monitoring statistics relating to the use of RRSE are at Annex II. We are planning to increase the number of remote sensing monitoring points from three to five this year.
Note 1: Diffusion tube is a kind of simple instrument for measuring air pollutant levels. While diffusion tubes in general cannot achieve the same level of accuracy attained by the instrument deployed in the air quality monitoring station, their measured results could roughly reflect the relative pollution level and they are commonly used for studying the broad spatial distribution of air pollutants within a specific area.
Note 2: As the measurements only lasted for 21 days, and diffusion tubes in general cannot achieve the same level of accuracy attained by the instrument deployed in the air quality monitoring stations, and are more susceptible to influence by nearby environmental factors, the monitored data by diffusion tubes should be used for general reference only.

Published on: 2018-02-28

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