Source Apportionment and Modelling of PM10 in Hastings, New Zealand

Concentrations of PM10 regularly exceed the NZ National Environmental Standard (NES) of 50 μg m-3 (24-hour average) in many urban areas of New Zealand. Both receptor modelling and airshed modelling demonstrated that domestic emissions are the main source of particulate air pollution in Hastings on days when the NES is breached. For effective management of PM10, it is also important to quantify other source contributions, especially the natural component of PM10. Receptor modelling of PM10 identified that domestic emissions contributed 87% of the PM10 on winter days when the NES was breached in Hastings, while natural sources, including sea spray and dust, accounted for 8% of the PM10 on those days. Airshed model results suggest that, while 92% of ambient PM10 under worst-case conditions is from domestic emissions, this proportion scales down to 85% when natural sources are accounted for. Airshed modelling for worst case conditions identified a maximum 24-hour average PM10 concentration for all of Hastings of 170 μg m-{3} and some of the concentrations from domestic emissions were from other urban areas outside the Hastings urban area. The research assists with air quality management in Hastings by: a) quantifying the contribution of natural PM10 sources (which cannot readily be mitigated in strategies for reducing PM10); b) demonstrating a need to regulate domestic emissions beyond the urban boundaries of Hastings; and c) increasing certainty in the main source of PM10 and its relative contribution to the total PM10.