The emissions projections used in the mapping work are given in Table 1. Road traffic emissions of benzene are expected to fall to a small fraction of their 1996 value by 2009 as a result of current policies.

Maps of estimated annual mean background benzene concentrations for 1996 and 2009 are given in Figures 1 and 2. Concentrations in 1996 were greater than 1.542 ppb in the centres of several cities, such as London, Birmingham, Leicester, Manchester and Liverpool. Concentrations in all areas in 2009 are predicted to be well within the proposed limit value. The maximum estimated concentration is in central London and is 2.6 ppb in 1996 and 0.6 ppb in 2009.

Figures 3 and 4 shows that the estimated roadside benzene concentrations in 1996 and 2009 are expected to be considerably higher than in background locations. Table 2 gives a detailed analysis of the estimated roadside benzene concentrations in all the years from 1996 to 2010. Very few road links are expected to have concentrations higher than 1.542 ppb by 2006 and very few are expected to have concentrations greater than the limit value with a 20% safety margin (1.234 ppb) by 2008. Table 3 shows that the majority of the 15 links with the highest estimated benzene concentrations are in central London. Figure 5 shows the road links in this area in more detail.

* equivalent to limit value of 5 m gm^-3 with a 20% safety margin (or a limit value of 4 m gm^-3 with a no safety margin)

** equivalent to limit value of 5 m gm^-3 with a no safety margin