Investigations into inconsistent readings at a Port Hedland dust-monitoring station, which informs industry of high levels of dust pollution from export operations, have been closed with no explanation given for the estimated 18 months of unreliable readings.
Part of the Port Hedland Ambient Air Quality Monitoring Network, the Taplin Street Air Quality monitoring station first began to show discrepancies when, in April 2019, zero exceedances in the air quality guideline of 70 micrograms per cubic metre of particle matter with a diameter of 10 microns or less were recorded.
Four separate investigations were held between the initial April 2019 detection and the release of the Port Hedland Industry Council’s 2018/2019 Ambient Air Quality Monitoring Program annual report in November, 2019.
All four investigations found no faults or anomalies with the Taplin Street equipment, the overall network or weather events during that time, with the annual report showing there had been zero exceedances that year.
After the release of the report, the PHIC requested further investigation, with an extra monitor installed alongside the existing station on January 1, 2020, eventually proving readings had been inconsistent.
In a letter to the Department of Water and Environmental Regulation and community stakeholders, PHIC chief executive Kirsty Danby said once the inconsistencies were confirmed action was taken to examine the Taplin Street monitor, revalidate the data from other monitors in the network and asses the standards of the company contracted to manage the network.
“Despite extensive testing, including by the manufacturer in the United States, no faults or anomalies were found with the equipment that returned the inconsistent readings,” she said in the letter.
“Assessment of readings for the remaining monitors across the network has found good correlation and results that are within limits.
“The third-party audit found Ecotech met or exceeded Australian Standards in its management of the network.”
Because no faults could be found with the monitoring equipment, the PHIC said in a statement it was not possible to determine with certainty the correct readings for Taplin Street during 2018-19.
The council also stated it believed the Taplin Street monitor had been recording accurate data since January 1, 2020, when replacement monitors were installed.
There have been three exceedances from January 1 to August 13, 2020, with two in January “potentially attributed” to cyclone Blake.
Ms Danby said she was disappointed the inconsistent readings had occurred but that it was PHIC’s insistence on investigating the issue that had uncovered the anomalies.
“PHIC takes its role in providing data from the Ambient Air Quality Monitoring Network seriously,” Ms Danby said.
“We engage Ecotech, an appropriately qualified and experienced independent specialist air-quality consultant, to operate and maintain the network and generate fully validated monitoring data.
“In the past eight years exports have increased by almost 50 per cent but dust levels haven’t increased.
“In fact, dust events are currently at their lowest.”
PHIC has been responsible for developing and managing the Port Hedland Ambient Air Quality Network since 2010.
As a result of the State Government’s 2018 response to the Port Hedland Dust Taskforce recommendations, responsibility for operations and maintenance of the network will be transferred to the Department of Water and Environmental Regulation.
Although there is no date set for the handover of responsibility, it is expected to happen before the end of the 2020-21 financial year.