Shanghai's vehicle exhaust contributed to at least 25 percent of PM2.5?- the fine particulate matter 2.5 microns or less in diameter?- in the city's atmosphere. Bad driving habits such as rapid acceleration and deceleration, especially by diesel vehicle drivers, leads to worse air pollution, a senior environmental official said on Tuesday.

"Our previous research indicates that in some of the central business district, automobile exhaust fumes contributed to 50 to 60 percent of the PM2.5 source. This figure even reached 70 percent at times," said Zhang Quan, director of the Shanghai Municipal Environmental Protection Bureau.

Shanghai plans to implement a harsher vehicle emission regulation starting next year in an effort to curb the city's air pollution. The move was part of a collection of air control measures rolled out by Shanghai Municipal Environment Protection Bureau.

The city established its first air monitoring station to measure PM2.5?ten years ago and currently has 24 of them. It wants to become the first in the country to announce PM2.5 data publicly. PM2.5 is not included in the normal air quality monitoring system in China yet. Shanghai Mayor Han Zheng said earlier that releasing PM2.5 data would objectively reflect the true situation of the city's air pollution.

Zhang Quan added that in order to reflect the city's overall air quality, the upcoming PM2.5 monitoring stations "wouldn't be put at spots with relatively high or low measurements such as parks or industrial factories".

In the meantime, testing services for indoor air pollutants will be available free for Shanghai residents to help them circumvent health hazards and promote green living concepts. Such a service, provided by Shanghai Environmental Protection Industry Association, includes the measurement of PM2.5 as an indicator of the city's air quality standard.