The first mobile platform for chasing and analysing real-time vehicle emission factors and volatile organic compounds (VOC) in Hong Kong has been developed by the School of Energy and Environment (SEE) at City University of Hong Kong (CityU). The platform inspects the emission factors of vehicles, identifying high emitters and the source of roadside pollutants.

The On-road Plume Chasing and Analysis System (OPCAS) for on-road vehicle emission and ambient air quality inspection can be installed on any kind of automobile. It is equipped with advanced technologies including a condensation particle counter, a real-time aerosol monitor, an Aethalometer, an air analyser, a VOC analyser, a global positioning system and a video camera.

The OPCAS collects real-time plume samples from a target vehicle on the road. It takes about two minutes to determine pollutant concentrations, including VOC, fine suspended particulates, nitrogen oxides and black carbon, in the plume of the vehicle and the emission rates, based on carbon balance and fuel carbon content. VOC, suspended particulates and nitrogen oxides are major pollutants, responsible for smog that can worsen existing heart and respiratory problems, as well reduce visibility.

Professor Johnny Chan Chung-leung, Dean of SEE, said there is an urgent need to improve the air quality in Hong Kong. “CityU’s SEE strives to work with the industry to investigate the source of roadside pollutants through innovative research and technology,” Professor Chan said.

OPCAS acts like a mobile monitoring station, said Dr Ning Zhi, Assistant Professor in SEE. Depending on the research purpose, the system can chase a specific vehicle type or monitor the ambient air quality at a location, such as a gas station or tunnel.

“Only a small number of excessively emitting vehicles worsen the roadside pollution, according to a survey, and OPCAS can quickly identify these heavy emitters,” Dr Ning said. “The major reason vehicles emit excessively is poor maintenance and their old catalytic converters. OPCAS can immediately identify the condition of catalytic converters by reading the VOC concentration levels in the plume. The system’s quick inspection time and low cost complement current on-road vehicle emission inspection measures.”

The onboard equipment is operated by battery, Dr Ning said, so there are no emissions if it is attached to an electric vehicle. The system can be used to study the impact of vehicle emissions in the Pearl Delta region in the future, helping to set up new environmental policies that will improve air quality in the region. OPCAS also raises awareness about air pollution.

OPCAS is sponsored by the Hong Kong Bio- and Eco-Energy Industry Association and SEE’s Ability R&D Energy Research Centre, supported by equipment from V&F (Austria) and Guyline (Asia) Ltd.

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