Wednesday, 11 September

The Hawke’s Bay Regional Council Environmental Science team is publicly notifying greater levels of air pollution in Hastings than was previously recorded. New instrumentation, being trialled alongside older monitors since 2022, has shown that there were more air pollution events (exceedances) in 2022 and 2023 than had previously been notified.

HBRC has been monitoring PM10 in the Napier and Hastings airsheds since 2005. PM10 measures the concentration of particles of less than 10 micrometres in diameter and is commonly found in domestic wood fire smoke and vehicle exhaust.

The data from the new instruments shows seven more exceedances in 2022 and two more exceedances in 2023 than were previously notified. The Council is required to publicly notify any exceedances of the National Environmental Standards for Air Quality (NESAQ) set out in the Resource Management Act.

Hawke’s Bay Regional Council Air Quality Scientist, Jeremy Kidd says, “Whilst this is obviously disappointing, it is reassuring that we have found this discrepancy and will be able to ensure the more accurate measurement of the PM10 particles into the future. Despite the additional exceedances, the long-term trend still shows a decrease in PM10 concentrations.”

The data from the new instrument at the St Johns (Hastings) monitoring site will replace the older data and be available on our website from when the new instrument started recording in March 2022.

Further information

The instruments used to monitor PM10 (and later PM2.5) are known as Beta Attenuation Monitors (BAMs). After using BAMs for nearly 20 years, it was time to upgrade the monitoring technology.

BAMs measure PM10 by measuring the reduction of beta radiation across a filter on which PM10 is deposited. The mass of PM10 on the filter is proportional to the reduction of radiation and this is used to calculate the PM10 concentration.

The Council purchased new instruments that use a different method of measuring PM10. These optical sensors use light scattering to measure PM10.

The comparison was between the BAM, an optical sensor, and a reference method instrument. The reference method is a filter based gravimetric sampler which draws air through a filter and measures PM10 by the difference in the weight of the filter before and after sampling. This provides a standard against which the results of the other two instruments can be compared to.

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