Guangzhou is seeking to ease traffic congestion and curb pollution by limiting the number of vehicles on the road. It has suspended the registration of all new and used small and mid-sized vehicles this month and the monthly registration of such vehicles will be capped at 10,000. The move, announced at the weekend, makes Guangzhou the fourth mainland city to impose a quota system on car purchases. All registrations, including secondhand filings, are suspended this month to give the authorities time to work out further details of the plan. That includes how a breakdown of the quota will limit private, corporate and government car purchases. Small and mid-sized passenger vehicles are defined as not longer than six metres, with a seating capacity of 19 or fewer. Since 2007, the number of such vehicles in the city has risen by an average of 19 per cent a year. That raises their total to 1.67 million, lifting the total number of all vehicles in the southern metropolis to 2.41 million by the end of May. Significantly, road capacity has increased by just 2 per cent over the past five years due to a lack of land and funding for road building. Furthermore, there are three times as many vehicles as parking spaces in Guangzhou, China National Radio said yesterday, citing official statistics. The Guangzhou Municipal Transport Commission said the worsening air pollution from vehicle emissions had prompted it to act by following the actions of Shanghai, Beijing and Guiyang , in Guizhou province. In 1994, Shanghai became the first mainland city to introduce restrictions on vehicle ownership, by enacting a vehicle-plate auction. That helped the city limit the number of vehicles on its roads to about 1.95 million by the end of last year, compared with the nearly 5 million cars in Beijing. Beijing only introduced its quota system in December 2010, capping the rise in vehicle registrations at 240,000 a year. Citing official statistics, Autohome.com.cn, a major mainland news portal on cars, said that once the quota system was in place in Guangzhou, car sales would fall by about 47 per cent from last year's 226,190. But the curb would have little impact on overall car sales on the mainland, which topped 18.5 million last year. There has been heated debate over the efficacy of the curbs in easing traffic woes in mainland cities. Some accuse the authorities of overlooking some of the root causes - inadequate funding for public transport systems, a lack of parking facilities and ineffective police traffic management.