A pollution detection measure implemented by Hong Kong in 2014 has resulted in a drastic drop in pollution levels across the city.

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Reported first by NewScientist, Hong Kong, in its pursuit to combat air pollution implemented a new system that looked for polluting vehicles. This worked via installed sensors on highway ramps that made use of IR and UV beams to detect carbon monoxide, nitrogen oxide and hydrocarbon levels in tailpipe exhausts of vehicles that passed by.

Cameras next to those sensors captured the license plates of the vehicles that were causing the pollution with the owners being notified about the same. Owners are required to either repair the vehicle and pass an emissions test to use the same vehicle back on the road or switch to a new vehicle entirely.

Since the implementation of this novel system in September 2014, the city has experienced a massive drop in pollution levels.

Based on an analysis led by Yuhan Huang at the University of Technology Sydney, since then, over 16,000 high-emission vehicles have been detected by the systems with 96 percent fixing their vehicles and passing the mandatory emissions test.