Poor air quality caused by traffic is still a problem in Warwick, Leamington and Kenilworth.
Exhaust from cars is the worst contributor to Warwick, which is a quarter higher than national pollution guidelines.
Richard Hall, Warwick District Council’s head of health and community protection, admitted that originally it was assumed heavy goods vehicles and buses would be responsible for most emissions of nitrogen dioxide in places like Jury Street and High Street,
But, in fact, domestic diesel exhaust from cars driving in and out of town is the main culprit.
The Low Emissions Zone study has also been carried out on busy roads in Leamington and Kenilworth.
In the High Street and Clemens Street area of Leamington the fumes from exhausts were recorded as 44 microgrammes in the first part of this year, compared with 46 last year, 48 in 2011 and 36 in 2010.
On the Parade the level was 44 microgrammes this year, compared with 37 last year, 37 in 2011 and 24 in 2010.
In Kenilworth the area studied was the main Warwick Road.
Emissions there have been recorded as above the national guidelines both for the first part of this year when they were 44 microgrammes - the same as 2012.
In 2011 records were 43 micogrammes, a huge leap up from 2010 when they were just 29.
The results should build a stronger case for Park and Ride schemes and cycle lanes.
A new report, just released to district councillors, shows that Warwick’s air quality measured between Jury Street and Theatre Street - as well as a second site near St John’s Church - was ten microgrammes per metre cube higher than nationally recommended levels.
Although Mr Hall points out that this does not necessarily mean the air is unsafe to breathe.
The latest raw figures for his Low Emissions Zone study show air quality from January to June this year was 50 microgrammes per metre cube.
This is lower than the 53 microgrammes recorded in 2012; and the 58.2 recorded in 2011.
Mr Hall said: “Domestic diesel fuel is the main culprit but with the increasing efficiency of engines the level of emissions has come down.
“What our report shows is that simply banning HGV vehicles from a town is not going to improve air quality - instead we need to look at ways of reducing the number of cars.
“In Warwick, as in other towns, enclosed streets are the reasons the levels of nitrogen dioxide build up.
“These levels only extend for a short distance and can quickly disperse.”
Hampton Street, next to the racecourse, was registered as 42 microgrammes last year but only 36 in the first six months of this year.
Members of the Warwick Society submitted a Freedom of Information request to gain access to the report as soon as it became available.
Increasing air pollution is one of their key arguments against the thousands of extra homes being considered in the Revised District Plan.