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2006 Local air quality management - Further Assessment Report

Executive summary

This Further Assessment Report follows on from the work reported in the Detailed Assessment published in 2004.  The Detailed Assessment presented evidence that the national air quality objective for annual average nitrogen dioxide was exceeded in a number of locations in the City.  As a result 13 Air Quality Management Areas (AQMA) were declared to identify geographical areas where these exceedances occurred.  In this report further data has been collated from both monitoring and modeling studies in each AQMA.  In addition, account has been taken of changes in both policy and development in the City.  New information has also been included concerning the sources of emissions.  This data has been used to re-evaluate the evidence for exceedances in 2005 and projections for 2010 have been made.  In addition, the main sources of emissions of nitrogen oxides in the City have been evaluated and the percentage reduction in emissions required to achieve the air quality objective has also been evaluated.  

The main findings of the Further Assessment Report are:-

• There is evidence to support the Detailed Assessment findings that the national air quality objectives are exceeded in 12 out of the 13 declared AQMAs.  However, there is conflict between monitored and modeled data for AQMA10 and no strong conclusions can be drawn for this Area.
• The report also concluded that exceedances would remain within AQMA 3, 6, 7, 9, and 11 in 2010 if the local authority took no local action to improve air quality.  The modeling study reports that in order to meet the air quality objective, a reduction in emissions of nitrogen oxides of between 3.8% and 43.9%, dependant upon Area, would be required in 2005.  In 2010, the requirements would reduce from 0% to 25.8%.  The greatest improvements are required in AQMA11 (25.8% reduction required in 2010) and AQMA6 (19.3% reduction required in 2010).
• The relative importance of the various sources of emission of nitrogen oxides has been determined from the modeling study.  The predictions for 2005 indicate that the dominant source of nitrogen oxides is from heavy diesel vehicles (HDVs).  The percentage contribution from this source ranges from 56.6% to 64.7%.  Contrary to the findings of the Detailed Assessment, the importance of shipping emissions is now considered to be relatively small (less than 10%).  In 2010, the pattern changes marginally with the contributions from HDVs ranging between 47.7% and 63%.
  Monitored data for a site (106 Victoria Road North) outside the currently declared AQMAs showed concentrations in excess of the annual average objective for nitrogen dioxide.  However, the modeling results at this location appear to under predict concentrations by 26.1%.  The need for a new AQMA in this location will be reviewed in subsequent assessments.

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