Urban air quality could be improved with a system of sensors designed to detect roadside emissions from high-polluting vehicles alongside an enforcement programme to inspect and repair those vehicles.

Vehicle emissions are the most significant source of air pollution in the urban environment worldwide, impacting the climate and the health of millions of people.

A recent study found that improving air quality can slow cognitive decline and reduce the risk of developing dementia in adults while another showed that the number of people in the US suffering from heart attacks fell during the Covid-19 lockdowns, as air quality improved due to lower traffic.

Reducing air pollution is also a key target of the United Nations sustainable development goals.

“Car exhaust fumes contain poisonous gases such as carbon monoxide, nitrogen oxides, and particulate matter that cause lung cancer, heart failure, asthma and other diseases,” said co-author of the new study, Professor John Zhou from the University of Technology Sydney (UTS).

“Remote-sensing equipment uses a sensor and light beam to measure chemical concentrations in the exhaust as a vehicle drives past. A camera records the licence plate, so vehicles can be identified for inspection and repair.”

Although new cars are required to meet emissions standards, older cars, those with high mileage, and cars that have been modified or not well maintained, can malfunction and have significantly higher emission levels, leading to high levels of air pollution.

The UTS researchers analysed the accuracy and effectiveness of Hong Kong’s remote-sensing enforcement programme.