The UK towns and cities with the most pollution relative to their size have been revealed – and Stevenage is one of the worst offenders.

Research by the universities of Birmingham and Lancaster compared pollution levels - focusing primarily on exhaust fumes - in 146 places around England, Scotland and Wales.

Of the top 10 worst offenders - relative to size, traffic and population - Stevenage ranked in 6th place, with Luton taking the top spot with the highest concentration of traffic-generated nitrogen oxide gases, which are a major health concern.

London, as you would expect, still produced by far the most pollution, but people using public transport meant a smaller proportion lingered in the air compared to places where people are heavily dependent on cars.

Smaller areas may produce less pollution, but the air tended to be more toxic, because in larger cities - while there was likely to be more traffic putting out more fumes - there were also more people and more space, reducing the concentration in the air.

Lead author of the research, Professor Rob MacKenzie, said: "What we're interested in is not just how much pollution is produced, but how much is in the air. Our new study shows how effective the particular urban form of a city - its layout and the types of building - is in dispersing the pollution.

"Using this type of analysis will help planners make those important decisions that find the right balance between spreading out urban development and providing sufficient green spaces, but also managing emissions by transporting people efficiently and heating homes efficiently."

In Stevenage Borough Council's 2018 Air Quality Annual Status Report - the latest available information - it says the town's air quality 'continues to remain good', but suggests people could help improve the air quality by using 'the excellent network of cycle paths across the borough', ensuring cars are serviced regularly and reducing the use of cars for short journeys.

In June last year, the council declared a climate emergency and committed to reducing carbon emissions.

At the time, Councillor John Gardner - the borough council's executive member for environment - said: "By taking action together we can help save the planet we share."