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Report says quarry particle emission does not pose health risk


Last updated 1/24/2008 at Noon

Submitted by Karie Reuther

Liberty Quarry/Granite Construction

A new study on the potential impact of crystalline silica associated with Liberty Quarry demonstrates that silica dust at the project site will not negatively impact the health of surrounding residents.

The study modeled likely ambient levels of crystalline silica resulting from the activities of Liberty Quarry in comparison with actual measurements taken from nearby aggregate material facilities in California and found that in all cases, the levels remained well below strict state standards.

“The State of California has introduced a Reference Exposure Level (REL) for ambient exposure to silica that incorporates significant safety margins for known and suspected health effects,” said Patrick Hessel, PhD, who conducted the study with Epilung Consulting, Inc. “The levels of dust projected to arise from the proposed quarry are significantly below this very low reference level.”

Silica dust is a very common and naturally occurring mineral. Several other sources in the area, such as the Interstate 15 Freeway and residential developments, would produce more silica dust than the quarry.

To ensure the health and safety of area residents, Liberty Quarry has a number of mitigation measures in place to limit the amount of emissions that could be released into the atmosphere by the proposed project. These measures include a requirement that there be no visible dust within 100 feet of any equipment or beyond the property boundary line and several other measures specifically intended to reduce dust emissions such as enclosing equipment and conveyor belts.

“Ensuring the health and safety of our neighbors will always be a priority for Granite Construction,” said Gary Johnson, Aggregate Resource Development Manager for Granite Construction. “Liberty Quarry is a prime example of how we are continuing our commitment to protecting residents and the environment and delivering much needed building materials for our region. This study is also supported by South Coast Air Quality Management District monitoring conducted near quarries in the Irwindale area that demonstrates no significant levels of dust near those quarries.”

For a complete copy of the report please visit our Web site at


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