Sheffield’s air quality was the best in the UK last year, according to government figures.
But there were also six days when air quality was so poor it could potentially be harmful to healthy people.
On a scale of one to 10 - where one is best and 10 is the most polluted - Sheffield’s average for 2013 was 2.1, beating Leicester, Portsmouth and Belfast at 2.3.
However, the city matched the West Midlands in the number of potentially ‘bad air days’ at six.
Neil Parry, of the East End Quality of Life Initiative, said: “It’s still bad in Sheffield - we get it bad when there are lots of cars about in rush hour.”
Each month volunteers measure air quality in different areas of Sheffield using diffusion tubes.
Neil said: “There’s no doubt about it - air quality is bad on arterial routes in Sheffield - not just in the East End but also in the likes of Broomhill. If you look at the readings for last year, the readings in Broomhill are the highest. And that’s in a leafy, prosperous suburb.”
Coun Jack Scott, cabinet member for environment, said: “There are small pockets in Sheffield where traffic – or the impact of the M1 motorway in particular - is a factor on air quality. But in the main Sheffield is a green and healthy city, which is great to see backed up by the facts – that we are one of the cleanest cities in the country in terms of average air quality.
“We are doing a massive amount to work on the air quality issues that are still lingering. This includes bringing in cost-effective new measures to deal with pollution based on recent high quality research.”