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Seasonal Variations in PM10 Emissions in Tokoroa 2005

TR 2005/55
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Report: TR 2005/55

Author: Emily Wilton, Environet Ltd

Abstract

Concentrations of PM10 (particles in the air less than 10 microns in diameter) regularly breach the ambient air quality guideline and National Environmental Standard (NES) for PM10 of 50 µg m-3 (24-hour average). The maximum measured 24-hour average PM10 concentration for Tokoroa was 97 µg m-3. In addition to being in breach of the 24-hour average guideline for Tokoroa, annual average concentrations regularly exceed the ambient air quality guideline of 20 µg m-3.

Emission inventory studies have evaluated the contribution of different sources to 24-hour average PM10 emissions in Tokoroa. These studies indicate the main source of daily wintertime PM10 in Tokoroa is domestic home heating, which contributes around 85 per cent of the emissions. As the inventory studies have focused on the wintertime worst case emissions, it is uncertain what the relative contribution of different sources are to the annual average PM10 concentrations in Tokoroa.

The purpose of this study was to evaluate seasonal variations in domestic home heating emissions, to determine the impact of this source across all months of the year. A secondary objective was to evaluate seasonal variations in outdoor rubbish burning. This was done using a domestic home heating survey of home heating methods and fuels and outdoor burning for each month of the year.

Results indicated that the domestic heating contribution to daily PM10 emissions ranged from 28 per cent during the summer months to 89 per cent during the winter. Other significant contributors during the summer months were outdoor burning (35 per cent) and motor vehicles (32 per cent). Overall the domestic heating contribution to total annual PM10 emissions was around 78 per cent.

The monthly emissions data were used in conjunction with PM10 concentrations observed at the Tokoroa monitoring site to provide an estimate of the relative contribution of different sources to annual average PM10 concentrations. Results suggested that domestic heating contributes around 69 per cent of the annual average PM10 concentrations with motor vehicles, industry and outdoor burning each contributing 14 per cent, 2 per cent and 15 per cent. No assessment of the contribution from Kinleith or natural sources was included in the analysis.

Seasonal Variations in PM10 Emissions in Tokoroa 2005 [PDF, 175 KB]