Air

Mission

To protect the health and well being of the community by achieving and maintaining satisfactory air quality through intervention in the planning process and by enforcing the controls in the Air Pollution Control Ordinance and the Ozone Layer Protection Ordinance.

Cleaning The Air At Roadsides

The Lamma Power Station has installed flue gas desulphurisation systems (the structures next to the two chimneys) as one of the measures to comply with the emission cap imposed on the licences for power generation plants.

The Lamma Power Station has installed flue gas desulphurisation systems (the structures next to the two chimneys) as one of the measures to comply with the emission cap imposed on the licences for power generation plants.

The air quality in Hong Kong and the region is affected by multiple, often moving sources. Vehicles, vessels, power plants, industry and products containing volatile organic compounds all contribute to air pollution. Hong Kong and Guangdong have been working together to tackle this problem and in 2011 we received welcome confirmation that our efforts are paying off.

Nine years previously, in 2002, we set targets to reduce pollutants by certain levels by the end of 2010. The data available in 2011 confirmed that Hong Kong had not only met its targets but exceeded every one of them. There will be further improvements as power plants, which contribute to background and regional air pollution, are required to reduce their emissions by 34-50 per cent from 2015.

Hong Kong also measures roadside air quality, which most affects people living or working near street level in urban areas. Here, too, the news has been quite encouraging – levels of respirable suspended particulates (RSP), nitrogen oxides (NOx) and sulphur dioxide (SO2) have fallen by a third or more since 1999. However, levels of nitrogen dioxide (NO2) have increased, particularly in the past three years.

This trend must be reversed if we are to secure cleaner, healthier air for Hong Kong. The Government therefore has introduced a broad programme to tackle the main source of this pollutant – motor vehicles – as a priority in its fight against air pollution.

Progressing in Measured Steps

The effort to achieve cleaner air is a long and arduous one. Over the years the Government has introduced subsidies for cleaner technologies, imposed stricter controls on power plant emissions, introduced cleaner fuel and vehicle standards, limited the content of volatile organic compounds (VOCs) in selected products, and worked with Guangdong on the Regional Air Quality Management Plan.

Breakdown of sources of air pollution in Hong Kong in 2010

Breakdown of sources of air pollution in Hong Kong in 2010

Enlarge Breakdown of sources of air pollution in Hong Kong in 2010See Data Breakdown of sources of air pollution in Hong Kong in 2010

Hong Kong’s emission reduction targets

Hong Kong’s emission reduction targets

Enlarge Hong Kong’s emission reduction targets

As a result, we have made excellent progress in reducing emissions of four major pollutants – SO2, NOx, RSP and VOCs – by between 30 and 59 per cent, out-performing our original reduction targets of 20 to 55 per cent (see table). We are now working with our counterparts in Guangdong on a plan for future improvements to air quality.

Roadside air quality has also improved on several measures, as mentioned above. RSP, NOx and SO2 levels have dropped by between 28 and 56 per cent since 1999 (see chart). Unfortunately, the concentrations of NO2 have increased by 23 per cent over the same period.

NO2 is formed by a combination of factors. The emissions of poorly maintained vehicles, mixed with ambient ozone under sunlight, give rise to NO2 and also to smog. Although Hong Kong has made good inroads in controlling most vehicle emissions, as evidenced by the drop in the other pollutants, there are lingering problems.

Vehicle maintenance is clearly a concern. So are very large vehicles, such as buses, whose emissions are much higher than smaller vehicles. The Government made progress in addressing these concerns in 2011, as well as in exploring alternative and innovative technologies that both address the NO2 problem and achieve continued overall improvements in our air quality.

The level of roadside air quality is largely influenced by the volume of traffic flow on the roads in an area.

The level of roadside air quality is largely influenced by the volume of traffic flow on the roads in an area.

Roadside air quality trends in Hong Kong 1999-2011

Roadside air quality trends in Hong Kong 1999-2011

Enlarge Roadside air quality trends in Hong Kong 1999-2011See Data Roadside air quality trends in Hong Kong 1999-2011

Vehicle Maintenance is Essential

Between 2000 and 2005, the Government has provided more than $1.2 billion in grants to switch taxis and public light buses from diesel to cleaner liquefied petroleum gas (LPG) vehicles and to retrofit oxidation catalysts to pre-Euro diesel vehicles to reduce their emissions. These measures achieved immediate improvements in air quality. However, in order to sustain the benefits, the vehicles need to be regularly maintained.

A brand new catalytic converter (left) and a used catalytic converter with deposits from vehicle engine exhaust (right).

A brand new catalytic converter (left) and a used catalytic converter with deposits from vehicle engine exhaust (right).

Two measures that help to improve roadside air quality: remote sensing equipment that detects on-road vehicle emission levels (left), and a chassis dynamometer that test vehicle compliance with statutory emission standards (right).

Two measures that help to improve roadside air quality: remote sensing equipment that detects on-road vehicle emission levels (left), and a chassis dynamometer that test vehicle compliance with statutory emission standards (right).

Enlarge Remote sensing equipment detecting on-road vehicles emission levels (left) and chassis dynamometer testing vehicle compliance with statutory emission standards at designated vehicle emission testing centres (right), both help improve roadside air quality.

Poorly maintained petrol and LPG vehicles emit excessive colourless exhaust gases. If their catalytic converters are worn down, their emissions can exceed normal levels by 10 times or more. About 80 per cent of taxis and 45 per cent of light buses emit excess pollution and require repairs, such as replacing their catalytic converters. In busy urban corridors they contribute 39 per cent of nitrogen oxides and 55 per cent of hydrocarbons – both major causes of “very high” readings in the roadside Air Pollution Index.

To address the problem, two measures were announced in 2011, one aimed at detecting excessive emissions, the other at helping the taxi and light bus trades to replace their worn down catalytic converters. From 2014 roadside remote sensing equipment will be deployed to screen out petrol and LPG vehicles with excessive emissions, and owners will be required to rectify the problem. Their vehicles will also need to pass within 12 days an advanced emission test conducted with the aid of a chassis dynamometer at a designated vehicle emission testing centre. Failure to do so will lead to cancellation of the vehicle licence. This requirement is in line with the existing Smoky Vehicle Control Programme for controlling diesel vehicles.

Assistance in the form of one-off subsidies will be offered to taxi and light bus trades, whose vehicles tend to have high mileage and require frequent replacement of the catalytic converters. Some $150 million has been earmarked for the subsidies, which will help owners of LPG taxis and light buses to replace the catalytic converters and oxygen sensors in their vehicles and appreciate the need and merit of doing so. It is hoped that this new measure will help to tackle this major source of roadside air pollution.

Greening Bus Transport

LPG and petrol vehicles are of course not the only reasons behind higher roadside pollution. Franchised buses are another highly-visible contributor. The Government announced several measures in 2011 to reduce their emissions.

Euro II and Euro III buses form the bulk of bus fleets in Hong Kong.

Euro II and Euro III buses form the bulk of bus fleets in Hong Kong.

One of the challenges in reducing bus emissions is that it is expensive to remove older, more polluting vehicles before the end of their useful life and replace them with cleaner vehicles. However, they can be retrofitted with devices to reduce their pollutants. Pre-Euro and Euro I franchised buses were previously fitted with diesel oxidation catalysts that can reduce RSP emissions by about 30 per cent, while Euro II and Euro III buses were retrofitted with diesel particulate filters that can reduce RSP by about 80 per cent. These devices have helped to contribute to a 34 per cent drop in RSP at roadsides today compared to 1999.

However, the above retrofit does not solve the NOx emissions problem. In 2011 a trial scheme got underway to retrofit Euro II and Euro III franchised buses with selective catalytic reduction devices that will reduce NOx emissions to levels comparable to cleaner Euro IV buses. If the results are satisfactory, the Government will fully fund the retrofit of the devices in Euro II and Euro III buses.

That addresses the current NOx problem. But the Government also wants to achieve more radical improvements in future by moving to zero emission buses or the most environmentally-friendly buses. It has proposed to fully fund the cost of procuring six hybrid buses for trial by franchised bus companies along busy corridors in Causeway Bay, Central and Mong Kok, to test their operational efficiency and performance under local conditions. Bus companies can also receive support for testing other environmentally-friendly buses. For this purpose, the Government has also earmarked $180 million for franchised bus companies to purchase 36 electric buses for a trial run to assess their performance under different conditions.

The presence of low-emission buses (i.e., buses that meet Euro IV emission standards or better) provides an opportunity to reduce pollution in busy areas by keeping out the more polluting buses. Pilot low emission zones for franchised buses were being set up in busy corridors in Causeway Bay, Central and Mong Kok. The goal is to increase the ratio of low-emission buses in those zones, with a target of making them low-emissions-buses-only by 2015.

Retrofitting selective catalytic reduction devices (left) on Euro II and Euro III franchised buses and setting up pilot low emission zones in Causeway Bay (right), Central and Mong Kok were two of the air pollution abatement measures announced by the Government in 2011.

Retrofitting selective catalytic reduction devices (left) on Euro II and Euro III franchised buses and setting up pilot low emission zones in Causeway Bay (right), Central and Mong Kok were two of the air pollution abatement measures announced by the Government in 2011.

Alternative Solutions

Image of an inner page of the Pilot Green Transport Fund

Electric and hybrid buses are innovations that can reduce vehicle pollution. The Government is keen to encourage more green alternatives on Hong Kong’s roads, so in March 2011 it launched the $300 million Pilot Green Transport Fund which will support trials of green and innovative transport technologies by the public transport sector and goods vehicle owners.

The fund offers subsidies for new vehicle types, equipment or machinery related to transport activities, and new retrofit systems, and covers part of a product’s cost including the installation of supporting facilities such as charging facilities for electric vehicles. An operator can test out different products to a maximum of $9 million subsidy per application or $12 million in total.

The first batch of subsidies was approved in the autumn of 2011, covering 13 projects and a total of almost $50 million. The projects related to the testing of 16 electric buses by the non-franchised bus sector and nine electric goods vehicles. The trials will start in 2012 and it is hoped they will pave the way for wider adoption of electric vehicles in the public and commercial transport sectors.

This is a hybrid bus running in London. Similar hybrid buses will be introduced to Hong Kong for trial. This is a hybrid bus running in London. Similar hybrid buses will be introduced to Hong Kong for trial.

Embracing innovation is essential if we are to achieve further reductions in air pollution and sustainably healthy air quality. Hong Kong, like the rest of the world, has paid a price for relying too heavily on fossil fuels. Cleaner alternatives will not only improve our air but also promote a low-carbon economy and the development of green technologies in Hong Kong.

Looking Ahead

  • Projects supported by the Pilot Green Transport Fund will get underway.
  • The Air Quality Objectives will be updated and air quality improvement measures for attaining the new AQOs will be taken forward.
  • Euro V emission standards will be implemented for all newly registered vehicles.
  • Measures to control emissions from marine vessels will be announced.
  • Legislative controls will be introduced on emissions from non-road mobile sources.
  • The way forward on controlling marine emissions will be charted with other governments of the Pearl River Delta region.

Topical Issues