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.”