Dust is a general term used to describe microscopic solid particles suspended in the air.
It is well recognised nationally and internationally that the most common metrics for measuring air quality is particulate matter (PM), specifically PM10 and PM2.5. This refers to the size in aerodynamic diameter measured in micrometres (μm).
The composition of dust can vary from location to location. In cities dust tends to be dominated by small particles from combustions sources, such as vehicle emissions. In regional areas, combustions sources are less concentrated, and dust tends to be dominated by larger particles. In Port Hedland, the composition of dust is significantly different, consisting largely of iron oxide.
The air quality is regulated by the WA Department of Water and Environmental Regulation (DEWR) under the Environmental Protection Act 1986 (WA).
DWER establishes the requirements for individual operators to manage, monitor and report on dust levels in accordance with licence conditions. All operators implement a range of dust mitigation measures which vary depending on specific licence conditions to ensure legal requirements are met.
PHIC established the Port Hedland Ambient Air Quality Monitoring Network (the Monitoring Network) in 2010 to closely monitor the overall air quality in Port Hedland.
Individual companies operate under a Part V environmental licence as part of the Environmental Protection Act, which sets out requirements to manage, monitor and report dust levels within the boundaries of their individual operations.
PHIC partner companies are committed to implementing leading fit-for-purpose dust mitigation and management practices.
A range of factors can be sources dust in Port Hedland such as:
- Ambient dust levels due to the nature of the semi-arid environment.
- Port activities – bulk material storage and handling.
- Other industrial activities – scrap metal processing, sand blasting, metal fabrication.
- Bushfires, pollen, sea spray.
- Dust storms.
Meteorological conditions play a significant role in the dispersion and generation of dust emissions in and around the town of Port Hedland.
The Pilbara region is an arid environment experiencing subtropical climatic conditions. Dry conditions and strong winds will result in a higher level of dust emissions from both industry and natural sources.
The dust emissions will also have a greater radius of impact during periods of stronger wind speeds due to dust remaining suspended in the air for longer periods and therefore being carried further distances.
The prevailing wind conditions during the wet and dry seasons of northern Australia can be variable.
The variability in the wind speed and wind direction in Port Hedland will result in variation of dust emissions and in the areas potentially affected by dust.
Wet conditions assist in the suppression of dust.
The direction of the wind determines where particulates in the atmosphere will travel. Another factor that influences particulates is the wind speed – low wind speeds reduce dispersion which can result in increasing concentrations of particulates while high wind speeds, which can increase the rate of dispersion, also results in wind erosion from open areas such the spoil bank.
Unseasonal or unusual wind patterns can impact can result in a variation to average seasonal dust outcomes. The classic example are the iconic dust storms that occur in the Pilbara when air from the base of a storm pushes dust upwards creating a wall of dust.
PHIC will continue to fund the ongoing operations of the Monitoring Network following its transfer to DEWR under a cost recovery arrangement.
The establishment and ongoing operation of the Port Hedland Ambient Air Quality Monitoring Network (the Network) was a key initiative of PHIC.
The Network has provided data and informed the development of strategies and evaluation of dust impacts from the Port of Port Hedland and has assisted industry to continuously improve its performance on dust emissions.
The transitioning the Network to the regulator was once of the recommendations of the Taskforce.
In line with that recommendation, PHIC is currently working with the Department of Water and Environmental Regulation (DWER) to transition the management of the Network to the regulator.
The transition to DWER is expected to take several months to complete.
As an industry group, PHIC and its members, bring substantial expertise in terms of dust mitigation and environmental knowledge.
Recognising this, a steering committee comprised of representatives of PHIC’s dust working group DWER staff, has been established to guide the transition.
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