Rising levels of harmful gases along part of Norwich Road/St Matthews Street are to result in it being registered as the fifth area of Ipswich to suffer from unacceptable pollution.

The section of the road from the Bramford Road junction outside Cumberland Towers to the Civic Drive roundabout is expected to be confirmed as an “Air Quality Management Area” by the borough’s executive meeting on Tuesday night.

The amount of nitrogen dioxide, mainly caused by diesel engines, has reached a level that is likely to breach the limit set down by the government.

That joins four other areas of the town: The Valley Road/Norwich Road/Chevallier Street junction, the Bramford Road/Yarmouth Road/Chevallier Street junction, Crown Street, and the St Helen’s Street/Grimwade Street/Argyle Street junction, as areas where the nitrogen dioxide level breaches government limits.

The borough has a duty to measure and record the level of this gas – and has to inform the county council, as highways authority, and Department for Transport(DfT) about any breaches.

But portfolio holder for public protection, Alasdair Ross, said it was very limited in the action it could take – beyond drawing the attention of people to the problems.

He said: “We pass on the figures to the county and the DfT but we cannot do anything ourselves to reduce the pollution.

“The county can take the figures into account when they are developing new road plans like the Travel Ipswich programme – but we cannot insist on that.”

Mr Ross said the one thing the borough could do was to take the figures into account if there is a planning application in an area of high pollution.

He said: “If someone wanted to build new homes or put up new community facilities in an area with high pollution it is a factor that could be considered by planners.”

And figures like this could take some time to have an effect on national government: “We hear that there is a long-term plan to stop building diesel vehicles but that still appears to be many years in the future.

“In the meantime all we can really do is to highlight the issues and monitor what is happening and hope that this is taken into account by residents and transport authorities.”