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Aerosol Sampling Program

ANSTO is playing a lead role in measuring and characterising fine particles from a range of locations around Australia and internationally.

Where does fine particle pollution come from?

Prof David Cohen revealing the sources of Sydney's air pollution

Rapid population growth has created a concurrent rise in fine particle pollution, generated by industry, trucks, coal-fired power stations, cars and other man-made sources.

Nature also generates fine particle pollution in the form of sea spray and wind-blown soil, dramatically illustrated in the September 2009 dust storms that hit Sydney and other areas.

While the human eye cannot see these fine particles - defined as particles with a diameter less than 2.5 micrometres, which is 40-50 times smaller than the diameter of a human hair - high concentrations of them can significantly reduce visibility. In fact, they play a key role in climate variability as they are very efficient in scattering and absorbing solar radiation.  

These fine particles can also cause significant health problems, as the human nose and throat are inefficient at filtering them out, meaning they can penetrate deep into the lungs and even our blood stream. The image below provides a  size comparison of some common airborne particles.

How big is small ASP
Image courtesy of Fairfax.

Explanation of Aerosol Sampling Terms

  • Units ASP

    Units

    All numbers given are for 2.5 μm diameter or less particles (PM2.5) and are measured in nanograms per cubic metre of air sampled (ng/m3), where 1ng equals one thousand-millionth of a gram and 1,000 ng = 1 µg, one microgram.

    All percentages are expressed as a percentage of the measured total fine particulate mass.

  • Weight ASP

    Weight

    This corresponds to the mean total weight of particulate matter, of diameter less than 2.5 µm, in the air for a corresponding 24 hour average during the month. The World Health Organisation (WHO) has a goal of 40,000 ng/m3 for less than 10 µm diameter particles (PM10).

    The US EPA recommends a PM2.5 goal of 15 µg/m3 for an annual average and 35µg/m3 for a maximum 24 hour average. Currently there is no such NSW standard for PM2.5 particulates. However, the Australian National Environment Protection Council (NEPC) proposed a PM2.5 goal of 8 µg/m3 annual average and 25 µg/m3 for 24 hour average for Australia in 2005.

  • Ammonium sulfate ASP

    Ammonium Sulfate, (NH4)2SO4

    This is an estimate of the amount of particulate ammonium sulphate [(NH4)2SO4] that is contained within a sample and it is obtained from the measurement of sulphur. Ammonium sulphate originates from the conversion of sulphur dioxide gas (SO2), from coal burning, industry and motor vehicles, to sulphuric acid (H2SO4), which is then neutralised by ammonia present in the atmosphere. The 'Acid Rain' problem arises when there is incomplete neutralisation of this acidic aerosol.

  • Organic matter ASP

    Organic Matter

    Organic matter is an estimate of any organic compound detected, Organics are those compounds generally containing carbon (C), hydrogen (H) and oxygen (O). In our case it is estimated through measurements of the hydrogen content with the removal of hydrogen associated with ammonium compounds.

  • Soil ASP

    Soil

    The fine particle soil concentration (PM2.5) is found from the summation of the different oxides found in soil such as silicon oxide (SiO2), aluminium oxide (Al2O3), iron oxides (FeO, Fe2O3), calcium oxide (CaO), and titanium oxide (TiO2).

    Soil in the atmosphere occurs from natural wind blown dust, agriculture and industries such as quarrying.

  • Elemental carbon ASP

    Elemental Carbon

    The visual degradation of an urban atmosphere is strongly influenced by the presence of elemental, black or sooty carbon. The elemental carbon concentration gives an indication of the amount of soot that is present and is obtained by a laser absorption technique on filter before and after exposure.

    It is mainly produced by motor vehicles and biomass burning. Our estimates assume a mass attentuation coefficient of 7 m2/g.

  • Sea Salt ASP

    Sea Salt

    In general sea salt is only a significant factor in marine environments, though its inclusion can show the seasonal variations in wind direction for coastal or near coastal localities.

    It is estimated from the measurement of sodium.

  • Potassium Iron Zinc Lead ASP

    Potassium (K) Iron (Fe), Zinc (Zn), Lead (Pb)

    The remaining four columns contain representative trace elements with particular source significance such as biomass or wood burning (potassium, K), industry and incineration (iron, Fe, zinc, Zn and lead, Pb) and automobiles (zinc, Zn and lead, Pb).

How fine particle samples are collected

Fine particle samples are collected on thin stretched Teflon filters and analysed using Ion Beam Analysis, which is a fast, sensitive and non-destructive way of establishing the chemical elemental and concentration of particles on the filter. The following animation illustrates the process: 

  1. Air is drawn through the air inlet via a narrow gap under the weatherproof cap

  2. It passes down through the stack tube and into the cyclone

  3. After entering the cyclone it begins to spiral where centrifugal forces remove the heavy particles

  4. The lighter PM2.5 particles then continue travelling upwards where they collide with the this stretched tefon filter surface and become trapped. After a set time the filters are removed from the cyclone ready for analysis

  5. Each Teflon filter is then analysed using accelerator-based IBA techniques, which provide a fast, sensitive and non-destructive way of establishing the elemental composition and concentration, more than 20 elements including for example silicon, iron, sulphur and lead, can be identified within the filter.

Aerosol measurement and fine particle characterisation

Aerosol measurement ASP

Determination of environmental pollutants by Particle Induced X-ray Emission spectrometry (PIXE) analysis of particulate matter on filter papers from air samples. A complete service is provided, including fine particle sampling units, PIXE analysis of filters using the STAR Tandedron facility, and full data evaluation. The number of running days required to successfully complete each project should be discussed with an ANSTO contact scientist before a proposal is submitted.

Access to aerosol measurement and fine particle pollution capabilities should be made via ANSTO's user office.

Capability Selections

  • Complete PM2.5 Cyclone sampling unit 
  • Ion beam analysis (IBA) particle analysis of filters: two per week, includes postage and despatch 
  • Black carbon measurements on filters 
  • IBA data interpretation and consulting

Complete PM2.5 Cyclone sampling unit

ANSTO can provide a self-contained PM2.5 cyclone sampling unit including pump and microprocessor control unit to turn off and on at pre-determined times. These units use a stretched Teflon filter designed specifically for ion beam analysis on our accelerators. Talk to our contact people for further information.

Black carbon measurements on filters

The black carbon content on filters can be determined by laser and LED measuring systems developed at ANSTO. Talk to our contact people for further information.

IBA data interpretation and consulting

IBA is a sensitive technique that can be used to estimate elemental concentrations in solid samples in concentrations from (µg/g) to 100% for most elements in the periodic table.

For further information contact