In the late 2000s, questions emerged about whether hydrogen cyanide (HCN) emissions from gold mining cyanide leach operations could pose a risk to nearby communities. Rather than relying solely on conservative assumptions or modeling, the U.S. Environmental Protection Agency (EPA) invoked its authority under Clean Air Act Section 114 to request real-world data. In response, Air Sciences, working closely with the Nevada Mining Association (NvMA) and its member companies, spearheaded a comprehensive ambient monitoring program designed to answer a simple but critical question: What are the actual ambient concentrations of HCN at the fence line of operating gold mines?
In February 2024, the Environmental Protection Agency (EPA) revised the National Ambient Air Quality Standards for Particulate Matter (PM NAAQS)—which officially went into effect in May 2024. Specifically, the EPA updated the primary (health-based) annual standard for PM2.5 (that is, particulate matter with diameters of 2.5 micrometers and smaller) from 12 to 9 micrograms per cubic meter.
To track emissions at the national level, the United States Environmental Protection Agency (EPA) requires Oregon (and other states) to conduct statewide inventories from all sources of air pollution. These data collected from across the country are used for making new rules and modeling air pollution.
A few years in the making, Cleaner Air Oregon (CAO) addresses this need and is already affecting many companies in the state. As of November 2018, all permitted facilities should have already submitted emissions inventories for their sources to the Oregon Department of Environmental Quality (DEQ).
The U.S. Environmental Protection Agency (USEPA) defines particle pollution into two categories:
- PM10 – Particulate matter with a diameter less than 10 microns,
- PM2.5 – Particulate matter with a diameter less than 2.5 microns, also known as “fine particles.”