Forecast distributions of species and their atmospheric reactivities for the UK VOC emission inventory

The planned reductions of volatile organic compound (VOC) emissions in the U.K, will have an influence on both the total mass and species distribution of emissions. Different organic compound species vary in their ability to react and produce ground level ozone and reactivity scales can be used to link primary VOC pollutant species quantitatively with ground level ozone formation. This report examines the changes in emission inventory species distributions based on sector-specific reduction forecasts and compares the reactivities of these distributions using photochemical ozone creating potentials (POCP). Despite the variability in compound distributions and planned reductions from different sectors, reductions are forecast to change the fractional distributions of species and their reactivities for the overall U.K. emission inventory only slightly by the end of the century. The distribution of national emissions based on an atmospheric reactivity scale remains relatively stable because the largest mass reductions are made from sectors with distributions estimated to be similar to the overall distribution. There is also a balancing effect of making simultaneous reductions from source sectors with average ozone creating potentials which are higher and lower than that for the current national distribution.