In 2016, people in Multnomah County learned that samples collected by the U.S. Forest Service suggested dangerously high concentrations of cadmium, arsenic and other toxic heavy metals in Portland-metropolitan area neighborhoods.

Even more disconcerting was that the presence of these metals and other air toxics in the Portland area has been recognized by the Oregon Department of Environmental Quality for years, but no immediate action had been taken to curb these dangerous emissions.

At the time, Oregon's emission rules were based on federal law, and allowed industrial facilities to release potentially harmful amounts of air toxics. Those findings spurred a public demand for action.

Gov. Kate Brown announced an initiative to establish emission limits based on toxicity, in addition to the proximity of those emissions to people. That initiative Cleaner Air Oregon, sets health-based limits on more than 250 air toxics