Witney's most congested street is to be tested again for its air quality.

West Oxfordshire District Council has commissioned monitoring of Bridge Street following a recent survey of Horsefair, in Chipping Norton.

Previous tests have shown that the two are are the most polluted streets in the district, with levels of nitrogen dioxide gas, produced from vehicle exhaust, are higher than recommended Government guidelines.

Air Quality Action Plans now have to be drawn up. In Chipping Norton there are proposals for the re-routing of heavy lorries, diverting them away from the A44 through the town centre.

Andrew Ward, the council's senior technical officer for environmental protection, said new monitoring of the levels in Bridge Street were next in line. Diffusion tube equipment would also be put in place at Mill Street as well as some of Witney's housing estates.

"We will be measuring the level of pollution now and later, after the Cogges Link Road or other traffic schemes are built," he added. "Hopefully the solution will come with that."

Oxfordshire County Council, the highways authority which supports the Link Road scheme, estimates traffic in Bridge Street would be more than halved after it is built in 2012.

Air quality targets set by the Government apply to roads with residential properties. Bridge Street has a mix of homes, shops and businesses.