Three forms of dust were measured during the Macdonaldtown Gasworks Remediation:
- Deposited dust;
- Total suspended particulate; and
- Particulate 10 microns in diameter or less (PM10).
Where and how often was dust monitoring conducted?
The following equipment was set up on the western boundary of the site, adjacent to the nearest residences, to monitor dust:
- A dust deposition gauge that collected dust continuously for later measurement at a laboratory; and
- A ‘DustTrak’ that measured PM10
In addition to the equipment listed above, a portable high volume air sampler (HVAS) was placed near the western boundary once a fortnight to measure PM10 over a 24-hour period. This monitoring was performed as a verification of the continuous PM10 monitoring performed by the DustTrak, in accordance with AS/NZS 3580.9.6:2003, a national standard for the measurement of PM10. After sampling, the HVAS filter paper was analysed at a laboratory accredited by the National Association of Testing Authorities (NATA). The results were then compared with those from the DustTrak to ensure that all PM10 monitoring results were representative. Total suspended particulate was also measured near the western boundary a number of times a week using a DustTrak.
What is PM10?
PM10 refers to any dust or particulate matter (PM) with an aerodynamic diameter less than or equal to 10 microns (10 millionths of a metre or smaller than 1/7th of a hair width). The symbol for a micron, also known as a micrometre, is µm. Particulate levels in air are measured in micrograms by the weight of the particles per cubic metre of air (µg/m3).
Health impacts associated with elevated PM10
PM10 is commonly in the air that we breathe. Monitoring PM10 in the atmosphere is important since elevated levels of particulate matter, especially fine particulate matter, can negatively affect the air. Elevated PM10 in the atmosphere can sometimes cause people to experience nose and throat irritation. It can also increase the number and severity of asthma attacks or reduce the body’s capacity to combat infection. When communities are exposed to elevated PM10 levels over long periods of time, some individuals may develop more serious health problems such as respiratory or cardiovascular disease.
Sources of PM10
Particulate matter includes a broad range of substances, with particles in the atmosphere originating from both natural and artificial sources. PM10 can include soil dust minerals, sea-salt and pollens, as well as particles from the combustion of fossil fuels in motor vehicles and industrial plants. Particles in smoke from bushfires and wood stoves are another sporadic source of PM10 emissions. The possible sources of PM10 during the Macdonaldtown Gasworks Remediation were excavated surfaces, stockpiles of soil and other materials, and emissions from vehicles and equipment.
Controlling PM10: the ECE and ECS
Dust, including PM10, was controlled during the main soil excavations by undertaking them inside an Environmental Control Enclosure (ECE) and by filtering all air extracted from the enclosure through an Emission Control System (ECS). The emission from the ECS was tested during the system’s commissioning to ensure that the level of total solid particles was below the limit specified in the Protection of the Environment Operations (Clean Air) Regulation, 2010. Water was also sprayed on internal roads and other areas to reduce dust when required.
PM10 Response Levels
A number of project goals and limits, known as Response Levels (RLs), were established at or below the maximum allowable goal for PM10 that is specified in the National Environment Protection (Ambient Air Quality) Measure (1998). PM10 measurements collected on and around the project site were compared to these RLs. The RLs were:
- A maximum concentration of 30 µg/m3 measured as PM10 continuously (DustTrak equipment) and measured over a 24-hour period (HVAS equipment). This was the project goal.
- A maximum concentration of 50 µg/m3, measured as PM10 continuously (DustTrak equipment) and measured over a 24-hour period (HVAS equipment). This was the project limit or maximum RL.
- In addition to the above, the project had the annual limit of 30 µg/m3 measured as PM10. This was included in the project limit or maximum RL.
The National Environment Protection (Ambient Air Quality) Measure (1998) advises that PM10 particulate measured over a 24-hour period is to have a maximum concentration of 50 µg/m3. The goal is to have no more than 5 days per year that this would be exceeded within a 10 year period.
PM10 monitoring results
From a community health perspective, PM10 results are more relevant than results for deposited dust or total suspended particulate. Monthly summaries of the environmental monitoring results obtained during the project, including PM10 results, are provided under the Monitoring Results section. See here