Wise words from an expert:
"Traffic counts are available on a DfT interactive map but I have summarised them below. Nitrogen Dioxide, the most critical pollutant, is mainly produce by diesels. There are many more diesel cars than diesel buses, vans and goods vehicles put together, but very roughly half the NO2 is from diesel cars and half from 'commercial' diesels. Diesels represent one third of the car fleet and half of all new cars.
You can see below that although total motorised traffic has been fairly steady over the years, commercial diesels on the A627 (the route through from the A6 to the M60) has increased substantially by more than 40% over the 15 years of records. The SEMMMS road is likely to make this worse as more commercial diesels from further afield make their way between the A6 and M60. Also worth noting that the SEMMMS traffic estimates for 2017 don't bear much resemblance to current traffic measurements.
The only air quality measurement site on the route is on Torkington Road near the A6. The SEMMMS assessment (blob diagrams) only considered the Torkington Road at the A6 end and concluded it was not at risk with or without the new road. I do remember that it was noticed by local residents that more heavy commercial vehicles were leaving the A6 towards the M60.
On a more ironic note, the SEMMMS team explained to the Public Inquiry that although levels were slightly above the limit in a handful of locations their estimates were very conservative particular after 'real' measurements had confirmed Euro 6 engines actually performed in real life like the Euro 6 tests predicted."