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Understanding air particulate matter pollution

This project investigates wintertime air particulate matter (APM) source variations with hourly resolution at multiple sites within an airshed to identify the actual source contributions and particle transport (horizontal and vertical) within airsheds. Size-resolved (PM2.5 and PM10) APM samples are collected simultaneously at three representative sites, along with meteorological data within each urban airshed.

GNS Science has been working closely with regional councils and unitary authorities for many years to determine airborne particle composition using state-of-the-art air filter and data analysis techniques to identify and quantify sources of APM within their polluted airsheds. Regional council sampling regimes for source apportionment studies have been limited to 24-hour integrated sampling aligned to the requirements of the NES.

Preliminary mass concentration analyses of eleven cities and towns across New Zealand using data supplied by regional councils have shown an unexpected but distinct 24-hour cycle in mass concentrations during winter (June to August) across all urban locations (see Figure below).

This observation is at variance with overseas research findings. Notably, the PM10 mass concentration data does not identify the APM sources contributing to the peaks nor describe the APM transport within each airshed. Critically, the peaks evident in Figure 1 can push the 24-hour PM10 average over the NES. Anecdotally, the peaks around midnight and 9 am have been attributed to morning rush-hour motor vehicle emissions, domestic fires or emissions from communities further upwind.
However, there are no data available to corroborate these suppositions. Our proposed research targets these knowledge gaps to answer fundamental questions on airborne particle composition, particle size, their emission sources and atmospheric processing – information critical to understanding and managing air pollution. The relative contributions from sources of particle pollution in urban airsheds on an hourly timescale have never been studied in the New Zealand context before and are crucial to understanding the sources and causes of air pollution.

This is achieved through development of a high-resolution air particulate matter (HAPM) model of atmospheric particle cycling over a 24 hour period for New Zealand airsheds:

  • collecting size-resolved (PM2.5, PM10) APM samples simultaneously at three representative sites within each urban airshed.
  • comparing four airsheds (two South Island and two North Island) to cover geographic range and population densities.
  • measuring the elemental composition of APM, including carbon compounds.
  • advanced data analysis to determine source contributions to APM.

Collaborators

  • New Zealand Map
  • GNS Science
  • Auckland Regional Council
  • Wellington Regional Council
  • Nelson City Council
  • Otago Regional Council

For more information, please contact Dr. Perry Davy