Ninety-two streets have been identified as black spots for vehicles with idling engines, with Kowloon City and Yau Tsim Mong the districts most affected, environment officials say. Many of these streets are near schools, tourist spots and bays for loading and unloading goods. The Environment Bureau would "request traffic wardens to pay more attention to [the] black spots during normal patrol duty", bureau chief Wong Kam-sing told legislators yesterday. The bureau would also conduct publicity and enforcement activities at those places, he said. The Motor Vehicle Idling Ordinance was introduced last December to reduce roadside pollution, the city's biggest air pollution problem. But its implementation has triggered public complaints that the Environmental Protection Department is too lenient in enforcing the law. In the 10 months since the law took effect, only three drivers have been charged a fixed penalty of HK$320 for keeping the engines of their parked vehicles running for more than the allowed limit of three minutes. The ban was also not enforced for 40 days during the recent summer because of overly hot or wet weather, in accordance with weather-related exemptions. In the meantime, roadside air pollution hit a peak of 212 in Central - the highest on record in the city with the exception of a sandstorm in 2010. Kowloon City was the district with the most black spots, with 15 streets, followed by Yau Tsim Mong with 12, officials said. A street was identified as a black spot if it received more than one complaint of an idling engine within three months, a government spokesman said. The department did not provide a breakdown of the exact locations of the streets listed. Yesterday afternoon, cars and school buses lined the Causeway Bay area outside St Paul's Convent School on Leighton Road, one of the black spots. While the two school buses had their engines turned off, some of the private cars had their motors left running as the drivers waited to pick up their young charges from school. Private cars, some with engines idling, were parked or double-parked in side streets leading off Leighton Road - including Sunning and Hoi Ping roads. Wong said traffic wardens and environmental protection inspectors had timed 806 vehicles across the city and held 340 publicity activities to raise awareness of the issue. He said more drivers now switched off their engines while their vehicle were parked, but admitted in some cases this was because law enforcement officers were timing them.