"The nitrogen oxides in the emission of diesel vehicles are 3.13 times of that in petro cars, and the inhalant particulate matter is even 10 times more," Du said.
Beijing requires that gasoline and diesel sold at all outlets in the capital city must meet the new China IV standards from the beginning of this year.
The current China III standards, equivalent to their EU counterparts,, have reduced sulphur dioxide emissions from automobile exhausts by 2,480 tons annually since it was enforced at the end of 2005, according to official statistics.
There are 3.1 million motor vehicles in Beijing and about 1,000 to 1,200 vehicles are adding to Beijing's roads every day.
Beijing faces tremendous pressure to improve its air quality ahead of the 2008 Olympic Games. Under the Olympic host city's ambitious "blue sky" plan, it must have 70 percent of the days in 2008 up to standard.
