The conclusion of the Stage 3 assessment of air quality in Hillingdon was that at various locations in the borough the nitrogen dioxide annual mean objective for 2005 and the particulate matter (PM₁₀) 24-hour objective for 2004 would not be met. For particulate matter this is restricted to areas around the M4 and M25 but for nitrogen dioxide this area extends over a large part of the south of the borough and along several road corridors, for example the Uxbridge Road, the A40 and the Hayes Bypass. The link below shows a map of where the NO2 annual mean objective is expected to be exceeded (areas marked in yellow, orange and red).

Map of predicted nitrogen dioxide annual exceedences in 2005

Hillingdon published a report and a leaflet for public consultation with regard to designation of an Air Quality Management Area. After this consultation exercise, it was resolved that in Hillingdon there would be one AQMA encompassing all the potential areas where the pollutant objectives would not be met. It was also decided to declare the area on the basis of the annual mean nitrogen dioxide objective, with an undertaking to carry out further more detailed work on the particulate matter areas in the next stage of assessment. However, in all cases, the provisional areas predicted to fail the particulate matter objective are well within the area covered by the AQMA. The AQMA Order was made and came into force on the 1st May 2001.

Following the publication of Hillingdon's Stage 4 Assessment it was concluded that the original AQMA Order could be revoked and replaced by a new version for nitrogen dioxide only. The area covered by the AQMA is the same as previously, but it is no longer expected that any PM₁₀ objectives will be exceeded. The new AQMA order came into force on the 1st September 2003 and can be viewed or downloaded via the link below.

The London Borough of Hillingdon Air Quality Management Order 2003 (pdf)