Canterbury residents are at no risk of serious health effects from airborne dust from quarries, health officials say.
Results from a four-month air quality monitoring programme run by Environment Canterbury (ECan), Christchurch City Council and Canterbury District Health Board were released on Friday.
They show that dust coming off quarrying sites in Yaldhurst is well below the international guideline for Respirable Crystalline Silica - a fine dust that can cause health problems.
However nuisance dust, commonly called PM10, is above the short-term guidelines on nine of the 120 monitored days. Of those, 13 exceedances spanned from one minute to less than a hour.
And now strict protocol for monitoring nuisance dust levels has been established.
"It is clear more needs to be done by all parties, including the quarry operators themselves to avoid dust nuisance issues, " ECan chief operating officer Nadeine Dommisse says.
"Today, we are signalling new tougher quarry dust management and monitoring requirements."
All quarries within 500 metres of someone's home are required to install dust monitors by December 1.
Enforcement action will be taken if the monitors aren't installed by the beginning of December, Ms Dommisse says.
The monitors will run continuously and be fitted with an alarm system. The alarm will alert the quarry manager if the quarry is getting close to the dust nuisance threshold.
The quarry is expected to take all action possible to reduce these levels so they aren't breaching the Ministry of Environment's one-hour nuisance dust guideline.
In 2016, Yaldhurst residents spoke out about concerns surrounding the potential health effects the dust from quarries could have.
"The joint agencies primary concern is the health of the community. We agreed it was important to understand if Respirable Crystalline Silica...was present in airborne dust around the quarries," Ms Dommisse says.
"And if so we need to determine if it is at a level that poses a long-term public health risk to residents."
Canterbury medical officer of health Dr Ramon Pink reviewed the results.
"Overall the results show there is no serious public health risk to Yaldhurst residents from airborne dust," he says.
"Nuisance dust will not cause long-term health effects, but we know it can cause irritation and symptoms of concern in some people."
A fact sheet of information has been prepared for residents, Dr Pink says.
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