PM2.5 concentrations

  • Image, PM2.5 concentrations.

    PM2.5 are particles 2.5 micrometres or less in diameter. They are largely produced from human sources, in particular burning wood or coal for home heating. PM2.5 is a component of PM10 and is associated with similar health effects, ranging from respiratory irritation to some forms of cancer. However, the smaller PM2.5 particles are more closely associated with severe health problems.

    We classified PM2.5 concentrations as a case study.

    Key findings

    In 2013, 4 of 10 monitoring locations around the country exceeded the World Health Organization (WHO) long-term (annual) guideline for PM2.5 concentrations. Seven exceeded the WHO short-term (daily) guideline.

    • Four locations (Timaru; Masterton; and St Albans and Woolston, Christchurch) exceeded the WHO long-term guideline between 9 and 40 percent.
    • Seven locations exceeded the WHO short-term guideline:
      • Penrose and Patumahoe in Auckland exceeded on one day
      • Wainuiomata exceeded on five days
      • Woolston and St Albans in Christchurch exceeded on 21 and 22 days, respectively
      • Masterton exceeded on 36 days
      • Timaru exceeded on 55 days.
    • The majority of these exceedances (96 percent) occurred from May to August (over colder months). This can be attributed to greater emissions from burning wood or coal for home heating and more settled weather conditions (reducing the dispersal of pollutants).

    Figure 1

    Note: Results at these monitoring sites do not necessarily represent the whole location. Suitable data are not available for all years. PM2.5 (particulate matter 2.5 micrometres or less in diameter) concentrations are in micrograms per cubic metre of air (µg/m3). WHO – World Health Organization. Data from Greater Wellington Regional Council; Environment Canterbury Regional Council; Auckland Council.

    Figure 2

    Note: Results at these monitoring sites do not necessarily represent the whole location. Regularly exceeding sites are those that exceeded the WHO short-term guideline in more than one year. Suitable data are not available for all years. PM2.5 – particulate matter 2.5 micrometres or less in diameter. Data from Greater Wellington Regional Council; Environment Canterbury Regional Council; Auckland Council.

    Definition and methodology

    Particulate matter 2.5 micrometres or less in diameter (PM2.5) is emitted from the combustion of fuels, such as wood and coal (eg from home heating and industry), and petrol and diesel (eg from vehicles). Natural sources have less influence on PM2.5 concentrations than PM10 concentrations. This means PM2.5 comes mainly from human activities.

    The four main human-made sources of key pollutants in New Zealand are burning wood or coal for home heating, road motor vehicle use, industry, and household outdoor burning.

    See Relative contribution of key human-made emissions for more details on emission rates for each key source.

    This case study reports the daily and annual concentrations of PM2.5 in micrograms per cubic metre (µg/m3). We compare the short- and long-term concentrations with World Health Organization (WHO) guidelines. Daily concentrations exceed the short-term guideline when they are above 25 µg/m3. Annual concentrations exceed the long-term guideline when they are above 10 µg/m3.

    The WHO short- and long-term guidelines recommend levels of protection against health risks from exposure to PM2.5. However, they do not provide complete protection as there is no threshold below which health effects do not occur.

    PM2.5 is only monitored at 10 locations around the country because monitoring is not mandatory under the National Environmental Standards for Air Quality.

    Data quality

    We classified PM2.5 concentrations as a case study.

    Relevance

     This case study is a partial measure of the ‘Airborne particles of concern to human health’ topic.

    Accuracy

     The accuracy of the data source is of high quality.

    See Data quality information for more detail.

    Supporting information

    Seasonality of PM2.5 exceedances 

     

    Published 21 October 2015

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