The estimates of concentrations of benzene and 1,3-butadiene calculated on the basis of the 1996 NAEI indicate that current national policies are likely to be sufficient to reduce roadside concentrations to below the objectives for the end of 2003 proposed in the review of the NAQS (DETR et al, 1999). The projections calculated here, based on the 1997 NAEI road transport model, confirm this conclusion.

Projections based on the 1996 NAEI indicate that very few road links are expected to have concentrations higher than the proposed EU limit value of 5 m gm^-3 by the end of 2006 and very few are expected to have concentrations greater than the limit value with a 20% safety margin by the end of 2008. A total of 12 road links are projected an annual mean benzene concentration in excess of 5 m gm^-3 with a 20% safety margin in 2009 for the predictions based on the 1997 NAEI, and a total of 75 road links are expected to have concentrations greater than the limit value with a 20% safety margin. The majority of the road links with the highest estimated benzene concentrations are in inner London. These links are also expected to be at risk of exceeding the proposed EU limit value for annual mean NO₂.

Comparison with EU Limit Value         Acknowledgements