Regulatory Criteria for Air Quality

Mid West Ports assesses all air quality monitoring data against regulatory criteria outlined in the Environmental Licence issued by the Department of Water and Environment Regulation (DWER). These criteria set the maximum acceptable levels of dust and metal particles in the air to protect community health and the environment. They guide how MWPA manages air quality to ensure port operations remain safe and compliant.

MWPA records and investigates all results that do not meet the specified in the criteria. MWPA reports air quality monitoring results to DWER, and regularly reviews performance to reduce emissions wherever possible. For more detail on our monitoring methods and results, visit our Air Quality Monitoring page or download the latest report.

Parameter	Frequency	Method	Averaging Period	Target (µg/m³)
Particulates as PM₁₀	Continuous	TEOM	10 minutes	50¹
Particulates as PM₁₀	During the handing of metal concentrates	High Volume Air Sampler	24 Hours	50
Copper as PM₁₀			24 Hours	1.0
Lead as PM₁₀			24 Hours	0.5 2.0 (Connell Road)
Nickel as PM₁₀			Annual Rolling Average	0.02
Manganese as PM₁₀			24 Hours	0.15
Lithium as PM₁₀			24 Hours	(No specified target)

Note 1: Target is compared against 24-hour average concentration

Air Quality Index

To enhance transparency and community engagement, MWPA also presents a simplified view of PM₁₀ air quality data using the Air Quality Index (AQI) via the Air Quality Portal. This index translates raw dust concentration values into colour-coded categories that are easy to interpret. The air quality index is comprised of five categories describing the air quality condition from ‘Good’ to ‘Extremely Poor’. The AQI replicates DWER standard as they display air quality information from across Western Australia using the AQI.

Importantly, the AQI and DWER’s regulatory targets are aligned: both use a 24-hour average PM₁₀ limit of 50 µg/m³ as the baseline for assessing air quality.

Under the AQI, values over 100 indicate that the PM₁₀ concentration exceeds this health-based standard.
Under MWPA’s Environmental Licence, any exceedance of the 50 µg/m³ 24-hour PM₁₀ target prompts further investigation and may require mitigation.

This dual approach - combining regulatory compliance with accessible public communication -ensures that MWPA not only meets its obligations but also builds trust with the local community through transparent reporting.