The results of the Environment Canterbury monitoring programme at Yaldhurst have been released, in a report made available on Friday 22 June. The report focussed on dust which could have adverse health effects, in particular respirable crystalline silica dust (RCS). The report concluded that there was no serious public health risk from quarrying activities, and that the results were well below the international guidelines for RCS.


The report was triggered by complaints from residents who live near the Yaldhurst Rural Quarry zone, who were suffering from adverse health effects, which they considered were caused by dust from the neighbouring quarries (in particular from RCS).

RCS is a basic component of soil, sand and aggregate (commonly quartz) which can become respirable when ground or processed. Inhaling RCS can lead to serious illnesses, including silicosis and lung cancer.

The report, commissioned by Environment Canterbury, sought to clarify the actual effects of quarrying, as prior testing in New Zealand has not identified whether or not RCS is present in dust from quarries. There are no national guidelines around safe exposure levels to RCS at a residential level, so international guidelines have been referred to by the report.

The monitoring was extensive, with ten different monitoring sites operated over at least a four month period. Monitoring occurred over the summer months – which are usually drier and windier, resulting in higher levels of dust generally.


The results from the monitoring show no serious public health risk from airborne dust – but established that nuisance dust levels do exist from time to time.

As a result, Environment Canterbury has signalled tougher quarry dust management and monitoring requirements. In particular, Environment Canterbury has signalled a requirement on all quarries operating within 500 metres of a residential property to install dust monitors on the boundary by December 1 2018.

There has been no explanation given to the justification for a 500 metre setback, or why small scale quarries (possibly without processing, and with small open areas) will be subject to the same rigid controls as large-scale quarries. We hope to see further advice on how this will work in practice issued by ECan shortly.

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