No serious public health risk from quarries
An air quality monitoring programme in Yaldhurst shows no serious public health risk to residents from airborne dust.
- Results well below the international guideline for Respirable Crystalline Silica dust
- Tougher enforcement promised
- Nuisance dust above short-term guideline for periods of time on nine of the 120 monitored days. On those nine days, there were 13 exceedances spanning from one minute to less than one hour.
The results, released today, follow a four-month monitoring programme run by Environment Canterbury, with Canterbury District Health Board and Christchurch City Council also involved.
Environment Canterbury chief operating officer Nadeine Dommisse said in late 2016 some Yaldhurst residents came forward with concerns about the health effects of dust coming from the quarries.
“The joint agencies’ primary concern is the health of the community. We agreed it was important to understand if respirable crystalline silica, a fine dust that can cause serious health problems, was present in airborne dust around the quarries. And, if so, we needed to determine if it is at a level that poses a long-term public health risk to residents.”
“We also wanted to understand how much nuisance dust was in the air, commonly called PM10 due to the size of the dust particles,” she said. “Ultimately, this led to the Yaldhurst Air Quality Monitoring programme.”
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 said. “Nuisance dust levels will not cause long-term health effects, but we know it can cause irritation and symptoms of concern in some people and we have prepared a factsheet with advice for residents.”
Dommisse said “While the results show there is no serious public health risk, there is a nuisance dust issue from time to time.”
“We appreciate nuisance dust is a concern for some residents, and we want them to know we have, and are, taking this seriously.”
“We agree quarry dust management hasn’t been good enough in the past. It is clear more needs to be done by all parties, including the quarry operators themselves to avoid dust nuisance issues,” she said. “Today, we are signalling new tougher quarry dust management and monitoring requirements.”
“We’re going to require all quarries within 500 metres of someone’s home to install dust monitors on their boundaries by December 1. If there is no practicable reason why these boundary monitors are not in place by December 1, we will be taking enforcement action.”
An example of how these boundary monitors work is that they run continuously and must be fitted with an alarm system to send the quarry manager a message if it starts getting close to the threshold level for nuisance dust. If the alarm is triggered the quarry will be expected to take whatever action they need to, such as stopping work or adding more water carts, to ensure the dust doesn’t breach the Ministry for the Environment’s 1-hour nuisance dust guideline level. If the guideline is breached the quarry will need to cease operations until dust levels have been managed to acceptable levels.
Quarry operators would have to make this data available to Environment Canterbury, and inform the regional council if there was a breach.
“If a quarry breaches the trigger level, we’ll investigate to find out what action they took to stop dust leaving the quarry before deciding what further action we need to take.”
The Yaldhurst Air Quality Monitoring programme was run by an independent company, Mote, and was designed with input from residents, the quarrying industry and the agencies involved. It was peer reviewed by international experts to ensure it was robust and comprehensive.
- RCS: we used the Californian Chronic Reference Exposure Levels (REL) for RCS. This guideline level is 3 μg/m3 as an annual average. A chronic REL is an airborne level of a chemical at or below which no adverse health effects are anticipated in individuals indefinitely exposed to that level (California Environmental Protection Agency).
- PM10: The Ministry for the Environment hourly guideline for nuisance effects is 150 μg/m3, and the 24-hour health guideline is 50 μg/m3.
- For more information read the Airborne dust and health effects factsheet.
- Reducing outdoor activity.
- Reducing vigorous exercise, especially if you have asthma or a breathing-related condition.
- Staying indoors in air-conditioned premises if possible and ensure regular maintenance of air conditioner filters and close windows and doors.
- Vacuuming indoors regularly with a high efficiency particulate air filter.
- infants and young children;
- the elderly;
- people with respiratory conditions, such as asthma, bronchitis and emphysema;
- people with heart disease; and,
ii. Excavation setback from site boundary within zone – 6 metres.
iii. Crushing and screening plant setback from zone boundary – 100 metres and below original ground level.
iv. Stockpile setback from zone boundary – 50 metres.