Improving air quality is no easy task and involves numerous stakeholders including the public, power plant operators, local industries, land transport operators and marine transport operators. A major contributor to air pollution is vehicle emissions—a challenge being tackled by the Environmental Protection Department (EPD). The EPD have focused their efforts in four key areas: vehicle emission standards, fuel quality, vehicle inspection and maintenance, and promoting the use of more environmentally friendly vehicles in Hong Kong.

There are numerous air pollutants emitted from vehicles such as nitrogen oxides (NOx) and sulphur oxides (SOx). The indirectly-generated pollutant of lower atmospheric ozone (O3) also has adverse health effects. Different air pollutants carry different health risks. So, the EPD has adopted a simple Air Quality Health Index (AQHI), which conveys the total health risks posed on the public in five health risk categories—ranging from ‘low’ to ‘serious’. This translation of complicated air pollution information into a simple index is critical for successful and effective communication with the general public. W. C. Mok, Assistant Director, Air Policy Division of the EPD echoed this advice with engineering students concerning their future careers, “Engineers tend to talk using technical jargon. As engineers, we need to know all the details, but we should also be able to ‘translate’ the key message so that a lay person can understand it too.”

Poorly designed vehicles obviously pollute, but if the fuel is not clean, even an environmentally-friendly car still emits plenty of pollutants. Moreover, even a well-designed car with good quality fuel will still pollute if it is not properly maintained. With this in mind, the EPD is fighting the environmental battle on many fronts to improve air quality. Since 2000, the EPD has made significant progress in further enhancing air quality in Hong Kong—monitoring two key environmental indicators: ambient air pollutant levels and roadside air pollutant levels. In general, air pollutant concentrations of both levels have decreased over the last 20 years and the narrowing difference between them indicates a decrease in overall vehicular emissions.

The EPD monitoring programme has been effective. Combating air pollution is, however, a complex issue involving a wide variety of stakeholders including industrial facilities, public transport operators, private vehicle owners and marine transport operators. Mr. Mok explained, “Private cars only account for a small percentage of air pollution. The rest comes from commercial vehicles such as taxis, light buses, buses and goods vehicles—so it is clear that the EPD’s work must focus on them.” To this end, the EPD has been working with transport industry representatives to implement various regulatory schemes. Mok added, “Mutual trust between the Government and the transport industry is very important for pursuing any policy, particularly regulatory ones. They might indeed have legitimate concerns. We do need to listen and see how to win their support.”

When the Government announced a proposal to strengthen the emission controls for LPG and petrol vehicles, members of the relevant transport trades were, understandably, concerned if their existing vehicle maintenance practices would meet the new EPD standards and what impact this would have on their business operations. The Government worked with the repair trade to clear up doubt, and mustered around 600 vehicles—identifying specific maintenance work required, and upskilling mechanics, so that subsequent emissions would then meet the proposed control requirements. Following that, the Government provided further assistance to operators and devised a set of maintenance guidelines to help them keep their vehicles compliant over time. Mr. Mok explained, “This approach of working in partnership is a good example of how engineers can help vehicle drivers and owners, who might not possess the required technical knowledge. Besides, many members of the transport industry do care about air pollution because drivers stay on the road more than most people.”

In terms of further reducing vehicular emissions in the future, the introduction of electric vehicles in Hong Kong brings exciting prospects. The Government has fully funded the purchase of 36 electric single-deck buses for franchised bus operation—eight of which have supercapacitors installed to facilitate much faster charging and can travel around 12 to 15 km after being charged for only a few minutes. Preparatory work for trialling supercapacitor buses on Hong Kong roads is already in progress. Challenges still exist, and Mr. Mok pointed out, “Gone are the days of simply spotting trucks that spew out thick black smoke. The technical challenge of detecting invisible pollutants is formidable.” He added, “The accurate detection of high NOx emissions from diesel vehicles fitted with catalysts for emission reduction is a technical challenge that we are working to resolve. We are working with the VTC-Jockey Club Heavy Vehicles Emissions Testing and Research Centre on this initiative.”

Engineers and technologists play a critical role in shaping the future of environmental protection and Mr. Mok concluded that whether chemical, civil, electrical or mechanical—engineering graduates’ expertise will continue to have an important role to play. By designing and developing more energy-efficient and environmentally-friendly solutions for today’s world, all of them are helping build a greener tomorrow.