Dust and Silica: What You Need to Know

Meridian Brick’s Aldershot East project will move forward safely and healthily for neighbours nearby.

That’s the preliminary conclusion of dust, silica and human health studies conducted as Meridian Brick prepares to open up the East cell of the Aldershot Quarry. Two consulting firms, Pinchin and Intrinsik, were hired to conduct the assessments, and both have found levels of dust and silica to fall below regulatory benchmarks, even under very conservative assumptions.

“The preliminary results are that the cumulative health risks to residents at all receptor locations are negligible,” said Glenn Ferguson, Senior Environmental Health Scientist with Intrinsik and Adjunct Professor in the School for Public Health and Health Systems and lecturer on Environmental Toxicology at the University of Waterloo who conducted the human health risk assessment.

That assessment applied to both levels of dust and levels of silica – and even those levels, according to Ajay Madan of Pinchin, will fall under guidelines set by the Province.  Madan has over a dozen years of experience in environmental consulting preparing air quality assessments for Environmental Compliance Approvals (ECAs) and air quality studies.

Studying the Centre and East cells at the Aldershot Quarry, Madan modeled dustfall and particulate levels based on three time periods: A five-year scenario, a 10-year scenario and a 25-year scenario. Even with estimates based on maximum production for every hour of operation during the year – an unlikely situation in the real world – estimates came in below guidelines set by the Province.

Estimated dustfall was measured not just within the quarry and Westhaven Drive, but throughout the Tyandaga subdivision. At no point of measurement did dustfall exceed the guidelines.

Those numbers informed the studies carried out by Ferguson, predicted particle concentrations at 35 different locations, not only measuring predicted dust from the East quarry, but also including background dust such as existing air pollution. He measured both short-term and long-term exposure to dust and silica.

In both cases, dust and silica exposure fell below both acute and chronic benchmarks. The study found “negligible” health risks expected for individuals in the surrounding community relating to dust and silica.

“It’s important to realize exposure to high concentrations of silica occurs primarily in confined workplaces,” Ferguson explained. Not only that, the minimum standards for silica exposure include a ten-fold safety factor. “You’d need significant and ongoing exceedances of that benchmark in order for serious health effects to occur,” he said – and the studies show that those overages will not happen.

All dust modeling was based on an extraction rate of 400,000 tonnes of shale per year – a level Meridian Brick likely will never reach. Presently, Meridian Brick extracts 250,000 tonnes per year.