1 Introduction
The Ministry for the Environment has prepared a number of reports reviewing the health implications of concentrations of air contaminants. These include technical reports for the 2002 ambient air quality guideline values (Dennison et al, 2002) and updates on the health effects literature currently being prepared. The latter have been prepared in two stages, the first being impacts of particles (PM10 and PM2.5) and secondly the health effects of other contaminants including carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), benzene and benzo(a)pyrene (BaP). This report considers the health effects literature in the context of concentrations of the latter contaminants currently measured in New Zealand. The purpose of this report is to provide an indication of the extent to which existing concentrations of air contaminants in New Zealand may compromise health. This data will be used to evaluate the health benefits of improving air quality in New Zealand through the implementation of national environmental standards.
Based on existing concentrations and health data, fine particles (PM10) have the greatest impact on people’s health in New Zealand. An estimate of their potential impacts is outlined in a previous report (Environet, 2003c). That report contains mortality estimates from Fisher et al (2002) calculated using the relationship derived by Kunzli (2000), which is based on concentrations of PM2.5 but describes the impact as being for the pollution mix. Although the studies upon which the equations are derived are also based on concentrations of particles, results are presented this way because of difficulties in controlling for concentrations of other contaminants.
This highlights a difficulty in estimating the impact of different contaminants on health particularly for dose-response relationships derived from epidemiological studies, because the relationships may be based on the pollutant mix rather than one individual contaminant. Although some estimates of the potential impact on health are made for specific contaminants in this report, these results should be treated with caution because of these uncertainties. They should not necessarily be considered additive to those already estimated to be caused by PM10.
