A report to be presented to the executive of Hounslow Council will show an alarming increase in the level of nitrogen dioxide (NO2) in the Chiswick area. This increased to the extent that it has risen above the levels seen on the Cromwell Road one of the busiest road in West London.

Most areas measured in London saw an increase during 2003 with the report suggesting that this could have something to do with weather conditions during the year. However the moderate rises at other sites were way below the 43% increase seen in Chiswick. This puts the area's level of NO2 at twice the target level for this particular pollutant.

Marylebone Road did see a high level in 2003 possibly due to drivers using the road to skirt around the congestion charge area. Chiswick's NO2 level was higher than that seen in the Marylebone Road in the year before the congestion charge.

The figures raise concerns that Transport for London's policies may be having disasterous consequences for Chiswick. It has been suggested that a combination of an increased number of buses combined with displaced traffic from the congestion charge zone are responsible. Concerns have also been expressed that the West London Transit System will cause a large diversion of traffic through north Chiswick. These points were put to Transport for London but they have yet to respond.

NO2 is the only pollutant measured at the green box outside the George IV where the measurements are taken.

NO2 is largely a secondary pollutant formed by the oxidation of NO. Road transport is the dominant source of NOX. This is reflected in the general distribution of NO2, with the highest concentrations being measured near roads and in central London locations.

The Chiswick area had been designated an Air Quality Management Area (AQMA) which meant that it was a priority area for reducing pollution in the borough. However, the Executive of the Council is due to consider a recommendation to designate the whole of the borough as an AQMA even though the associated report admits there would no longer be any focus on the worst affected areas.

The report makes no specific comment on the rise in NOx concentration in Chiswick.