Particulates
Types of Particulates: Particulates are a mixture of organic and inorganic substances suspended in the air. They can be solids and/or liquids and exist in a range of sizes. Particulate size is measured in micrometres (µ m), one millionth of a metre. In Newcastle a number of different size fractions are monitored. These include:
- Total suspended particulates (TSP) - representing the range of particulate matter normally found in the urban atmosphere. TSP generally includes from 1µm to 50µm.
- PM10 - refers to particulate matter of less than 10m m in diameter. PM10 is generally considered the most useful particulate measure. Particles less than 10µ m in diameter can be inhaled and have the potential to reach the tracheo-bronchial region of the lung.
- PM2.5 - comprises of fine particulate matter less than 2.5µ m in diameter. Particles of this size are capable of deep lung penetration.
Source: Major sources of particulates include combustion processes, motor vehicles, bushfires, domestic fuel heaters, power generation, stockpiles and transport of extractive materials, and some industrial processes. Particles can also originate from natural sources such as sea salt and soil particles.
Health Effects: Larger particles (10µ m or greater) are generally more of a nuisance to amenity than to health. They are large particles and fall out of the atmosphere relatively quickly thus impacting close to the source of generation. These large particles are generally filtered out by the nose and throat, because of this filtering the particles do not reach the lungs reducing the potential for health effects.
Smaller particles (<10µ m) hang in the air longer and can be transported greater distances from the source of generation. Due to the small size of these particles they have a greater potential to be inhaled into the bronchial regions of the lungs.
Particles less than 2.5µ m can be transported great distances and because of their small size they have the ability to penetrate deeply into the respiratory system. The chemistry of these particles also influences the potential to cause health effects. Chronic long term exposure to fine and very fine particulates with a toxic composition have been linked to lung cancer, heart and lung disease and asthma.
TSP Trends and Goals: Monthly average concentrations of TSP reflect the seasonal variations in prevailing winds. At Mayfield and Waratah, higher concentrations occur in summer when prevailing winds are from the easterly direction. At Stockton, higher concentrations generally occur during winter in north-westerly airflows. The National Health and Medical Research Council have recommended annual average goal of 90µ g/m3.
Monitoring Method: Australian Standard 2724.3Sampling is carried out continuously for 24 hours on a one-day-in-six cycle. It involves drawing air at a known flowrate through a filter paper mounted on a High Volume Air Sampler. The mass of total suspended particulates (TSP) is determined by weighing the filter paper before and after its 24-hour exposure.PM10 Trends: Generally these results do not experience the seasonal variation that is evident in TSP results. This is due to the smaller nature of the particles and their ability to be transported through the airshed. As a result, PM10 is more appropriately used as a regional air quality indicator rather than a measure of emissions from a localised source.
Monitoring Method: Australian Standard 3580.9.6. A size selective inlet (SSI) is attached to a high volume air sampler and samples are collected and weighed as for TSP every six days. The diameter of particles collected is less than 10 µ m.
