Only a small number of the emission inventories carried out in New Zealand have included an assessment of sources of benzene. These inventories indicate that benzene estimates should be treated with caution because of uncertainties regarding emission factors from different sources, in particular motor vehicles. Until more robust emission rates for benzene are established specific to New Zealand fuels and vehicles, emission inventories assessments that include benzene should be treated with caution.
Figures 7.1 and 7.2 show the emission inventory assessment of sources of benzene in Nelson, Richmond and Christchurch and Timaru. The assessment for Christchurch was not included in the Christchurch 1999 emission inventory but has been estimated for this report, based on the emission factors used for the Timaru emission inventory. In each of these areas, the main contributors to benzene emissions are motor vehicle emissions and domestic home heating.
Some VOC speciation data including estimates for benzene are included in the Auckland 1993 air emissions inventory. This is not presented graphically as sufficient speciation data were not provided for industry. However, data indicates motor vehicles are the most dominant source of benzene in Auckland. Domestic heating emissions were also significant, contributing two-thirds as much as motor vehicles.