The leader of Oxfordshire County Council, Keith Mitchell, has said the third set of damning pollution figures about the quality of air in Oxford are nothing to worry about.

Figures published this week by the National Union of Railway, Maritime and Transport Workers (RMT) labelled Oxford city centre as one of the most polluted in the country.

The RMT's general secretary Bob Crow said the council was burying its head in the sand and should act to lower pollution levels.

This was the third survey to condemn Oxford's air quality in less than a year.

The Chartered Society of Physiotherapy found nitrogen dioxide levels were one and a half times the Government limit.

Last August a Calor survey claimed that spending a day in the city centre was equivalent to smoking 61 cigarettes.

But Oxfordshire County Council has disputed all three surveys and says our health is not at risk.

Council leader Keith Mitchell said: "The council's air pollution experts are quite clear that there is no significant health problem in Oxford.

"We have seen repeated surveys that try to claim the opposite by using information selectively and distorting the real meaning of complex facts and figures.

"People in Oxford should be extremely wary of these surveys and those who seek to use them to champion their own causes."

Using Government Air Quality Archive figures, the RMT posts Oxford eighth in a table of the 28 worst offenders, behind Glasgow and six London locations, with average nitrogen dioxide levels at the roadside 58 micrograms per cubic metre -- way above the Government guideline of 40.

Mr Crow said it was time the county council stopped shooting the messenger and acted to lower pollution on the streets of Oxford.

He added: "It is the Government which says these readings are a problem so the council should be looking at what it can do."

The RMT has published the Department of Environment, Food and Rural Affairs (Defra) figures to kickstart a campaign to re- nationalise the railways.

An Oxford City Council spokesman said: "There is no doubt that there is a material air quality problem in the city.

"We know from our detailed assessment that it is worst in locations involving traffic congestion."

The spokesman added: "The city council will be working with the county council to agree a joint way forward via the local transport plan in July."