Hong Kong has improved its air quality by using roadside sensors to detect vehicles with the dirtiest fumes and forcing owners to get them fixed.
Vehicles that run on petrol and diesel emit harmful chemicals like carbon monoxide, nitrogen oxides, and hydrocarbons. New cars have the technology for reducing these emissions, but they can become more polluting over time. Many older cars that are still on the roads are heavy emitters.
To identify the worst-offending vehicles, Hong Kong installed sensors on highway ramps that use infrared and ultraviolet beams to detect carbon monoxide, nitrogen oxide, and hydrocarbon levels in tailpipe exhausts of passing vehicles.
Cameras capture the license plates of the most polluting vehicles, so their owners can be notified. Owners must repair their vehicles and pass an emissions test, paid for themselves, before their vehicles are allowed back on the road.
Since the enforcement program began in September 2014, more than 16,000 high-emissions vehicles have been detected and 96 percent have been fixed and passed the compulsory emissions test, according to an analysis led by Yuan Huang at the University of Technology Sydney in Australia.
The scheme has rapidly improved air quality in Hong Kong. In 2015, independent monitoring found that average concentrations of carbon monoxide and nitrogen oxides at roadside locations had dropped by 26 and 27 percent respectively compared to 2012 levels.
Figures from a separate monitoring program, the Hong Kong Air Pollutant Emission Inventory, also show that carbon monoxide and nitrogen oxide emissions from road transport declined, by 50 and 34 percent respectively, between 2012 and 2015.
Several European countries are experimenting with using roadside sensors to monitor vehicle pollution, but Hong Kong is the first to use them for enforcement purposes, says Huang.
He believes the technology should be adopted in other countries since it is relatively low cost and offers a quick and straightforward way to clean up the air. I think it’s an especially good idea in big cities like Beijing, which have serious air pollution problems from transport.
According to one estimate, air pollution kills 9 million people worldwide each year – more than smoking. Rather than killing otherwise healthy people, air pollution tends to aggravate the effects of heart and lung diseases, so working out the death toll is not straightforward. People exposed to air pollution in early life can still have a higher death rate decades later.
Population studies show that living in polluted areas is associated with a higher risk of asthma, reduced fertility in women, and lower scores on math and language tests.
There are two main components of air pollution: particulates and gases. Particulates are split into categories based on their size: PM2.5 means particles smaller than 2.5 micrometers; PM10 means particles smaller than 10 micrometers. The smaller ones are more damaging as they can penetrate deep into your lung tissues. Power plants, factories, gas cookers, volcanoes, car exhausts, and forest fires are all sources of particulate pollution.
Among the gases, nitrogen dioxide is considered the most harmful. Its main sources are diesel engines, indoor heating, and power stations. Ozone and sulfur dioxide can also be damaging to health.
Worldwide, the average PM2.5 concentration rose 11 percent between 1990 and 2015. This reflects large increases in air pollution in rapidly growing economies like China and India. In developed countries, concentrations of particulates and nitrogen dioxide have fallen thanks to tighter controls on vehicle emissions, but the rate of the fall seems to be slowing down.
Hong Kong has improved its air quality by using roadside sensors to detect vehicles with the dirtiest fumes and forcing owners to get them fixed.
Vehicles that run on petrol and diesel emit harmful chemicals like carbon monoxide, nitrogen oxides, and hydrocarbons. New cars have the technology for reducing these emissions, but they can become more polluting over time. Many older cars that are still on the roads are heavy emitters.
To identify the worst-offending vehicles, Hong Kong installed sensors on highway ramps that use infrared and ultraviolet beams to detect carbon monoxide, nitrogen oxide, and hydrocarbon levels in tailpipe exhausts of passing vehicles.
Cameras capture the license plates of the most polluting vehicles, so their owners can be notified. Owners must repair their vehicles and pass an emissions test, paid for themselves, before their vehicles are allowed back on the road.
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