It’s a cancer-causing chemical usually emitted during industrial processes.
It’s the third heavy metal the Portland Department of Environmental Quality says it’s concerned about.
Earlier this month, officials announced they had detected high levels of cadmium and arsenic near the glass factories.
A research study that looked at toxins in moss first revealed the air pollution.
Nina DeConcini, a senior manager for the Portland area at DEQ, said the companies involved were not violating regulations.
“This research has revealed areas where we need to look more closely at our permitting program to determine how me might address these localized emissions that are of concern.”
Bullseye Glass and Uroboros glass have voluntarily suspended their use of all three chemicals, which are used to color glass.
In a press release, Bullsye called the Department of Enviromental Quality’s actions “bizzare” and said that the agency had provided no evidence that the company was a significant source of chromium emissions.
“We are concerned that DEQ’s frantic actions could put us out of business and cause 140 people to lose their jobs,” the company said.
Earlier Friday, Oregon Sens. Ron Wyden and Jeff Merkley and Portland Congressman Earl Blumenauer asked the Environmental Protection Agency to help local officials determine how much of a risk the pollution poses to residents.