Research being carried out by Prof Barbara Maher of Lancaster University into pollution levels has revealed the extent to which people are being exposed to lead pollution from vehicles.

Prof Maher has been analysing roadside tree leaves from the one-way system, which carries around 30,000 vehicles a day.

The results showed that "PM10" emissions, which contain particles of iron, lead and carcinogens, were particularly high in Cable Street, and around Skerton Bridge.

Lancaster City Council's air quality monitoring station, in Water Street, takes measurements of PM10 emissions.

Its associated 'Air Quality Progress Report 2008' also showed an increase in these emissions from 2002 to 2007.

Prof Maher and her team found that concentrations of lead and iron particles were highest at the height of a small child, and also at adult head height. She called the emissions a "toxic cocktail" and added: "These results indicate that vulnerable groups, especially young children, continue to be exposed to fine, lead and iron-rich, vehicle-derived particulates." Prof Maher added that her research showed that roadside trees improved health by protecting people from pollution.

North Lancashire's Friends of the Earth (FOE) is calling on Lancaster City Council to further insulate buildings and fit green energy systems, claiming it could create 64 new jobs as well as slashing emissions.

FOE's campaign, Get Serious About CO2, is calling on councils to commit to cutting carbon dioxide emissions in their local area by at least 40 per cent by 2020 and produce an action plan detailing how they will make the cuts.

The city council said that over the next two years, with the help of the Energy Saving Trust, it would implement a climate change action plan.

A map showing the most highly polluted areas in Lancaster from vehicle emissions is due to be completed in the autumn.