An empirical model for attributing sources of particulate matter

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Davy PK, Trompetter WJ. 2020. An empirical model for attributing sources of particulate matter. Lower Hutt (NZ): GNS Science. 50 p. (GNS Science report; 2020/33). doi:10.21420/H7NX-HM56.

Airborne particulate matter (PM) pollution is well-known to have significant adverse effects on human health. It also has a range of environmental effects, including local reductions in visibility, effects on the radiative balance and deposition of contaminated material onto land and waterways. Because of these effects, PM concentrations are routinely monitored in numerous countries and managed according to local legislation.

In New Zealand, the National Environmental Standard (NES) for PM sets a 24-hour average limit for PM10 (particulate matter with aerodynamic diameters less than 10 µm) concentrations at 50 µg m-3 with regulatory authorities required to report exceedances and manage air quality to reduce pollution concentrations. Many urban areas in New Zealand exceed the NES repeatedly each year, particularly during the winter when wood combustion is used as a source of energy for home heating. Understanding the sources of air pollution and their relative contribution to total PM concentrations is therefore important for managing air quality to reduce the health impacts for exposed populations.

The National Air Particulate Matter Speciation Database (NAPMSD) held by the Institute of Geological and Nuclear Sciences (GNS Science), contains air particulate matter compositional data for samples collected since 1998 at various New Zealand urban air quality monitoring sites. The particulate matter composition data has been used to identify the sources and how much they contribute to PM pollution concentrations at those locations. This quantitative source contribution data has been used to construct and test an empirical model to help define source contributions at those locations where particulate matter concentration monitoring data (PM2.5 and PM10) is available but there is no breakdown by source contributions. The delineation of source contributions to total particulate matter concentrations is useful to inform both regional and national policy to mitigate the health and socio-economic effects of air pollution in New Zealand. The empirical model was found to reproduce the peak winter contributions from biomass combustion (wood burning) for residential space heating when compared to the source apportionment data for the same locations. The results are such that there is confidence that the empirical model can be used to estimate monthly and annual average contributions at those locations where PM2.5 and PM10 concentration monitoring data is available (but no breakdown by source) for use in health effects studies or assessing winter particulate matter concentration trends. (auth)