Metro Vancouver is developing a program to crack down on older diesel trucks, which are responsible for most of the diesel pollution in the Lower Mainland, officials with the regional authority said.

A roadside testing program has shown that three quarters of all trucks with unacceptable diesel emissions are model years 2007 and older.

"We did find it was a small number of vehicles -- the gross emitters -- that are emitting really large amounts and if we can address those then that will take care of a chunk of the problem," said Heather Deal, Metro's Environment Committee Chair.

Metro Vancouver used a remote sensing vehicle to test emissions from nearly 12,000 vehicles over a 55-day period last year.

Diesel trucks are not subject to the scrutiny other vehicles get through the AirCare program, but Deal said this would soon change.

"[We have] come out in favour of testing those trucks [and] cracking down on some of those vehicles. [People] are breathing these fumes and we know that they are very bad news in terms of health," Deal said.

Officials say they will develop a program that will include roadside testing, scrapping programs, retrofits and fees, with an emphasis on truck owners buying newer vehicles that meet modern emission standards.

The program is expected to be fully operational in two years, officials say.

With files from the CBC’s Terry Donnelly