The latest plan to build 380 homes to the north of Northampton will send more than 3,000 cars into Kingsthorpe each day and add to area's shocking air pollution figures.
That is according to Northampton's Green Party, which has lodged a formal objection to the Buckton Fields scheme.
The environmentally conscious party says the latest plans by Ensign Group Limited will force some 3,000 cars a day into an area that already regularly sees nitrogen dioxide levels exceed legal limits.
Northampton Borough Council launched plans to make the Harborough Road corridor less polluted as part of its Draft Low Emissions Strategy earlier this year.
Green Party Northampton spokesman Stephen Miller, said: "A large percentage of the journeys that will be made following the development of the additional 380 houses will travel along the Kingsthorpe corridor on a daily basis.
"If each of those 380 homes will result in seven or eight journeys daily, this will result in 2,660 to 3,040 additional trips each day.
"This has the potential to greatly affect traffic flow on those already congested roads, and contribute further to the levels of NO2."
The modelling for traffic flow in the development plans also appears to use data from 2011, when the Harborough Road was less busy.
The Green Party says this is "substantially out of date" and should not be used to accurately predict the number of journeys such a development could create in 2017.
"This means that any environmental impact assessment which uses those figures is inaccurate," Mr Miller added.
"I would ask that any decision regarding further development is placed on hold until such time as the developer has produced robust up to date projections of traffic flow."