In this March 17, 2016 photo, a man walks along a pathway beside the Willamette River in Portland, Ore. Fiercely protective of its reputation as one of the most eco-friendly cities in the country, Portland is reeling from the discovery of poisonous heavy metals in the air and the ground of neighborhoods where thousands of people live, work and attend school. Terrence Petty

Oregon regulators have results back from new air quality monitors installed after toxic hot spots were found in Portland. They show yet another reason for concern.

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The Oregon Department of Environmental Quality has been working to reassure the public after it confirmed very high levels of arsenic and cadmium in Portland's air earlier this year. Those chemicals were originally found in moss as part of a U.S. Forest Service experiment.

The new monitors tested the air near the Bullseye Glass Company in Southeast Portland and Uroboros Glass in North Portland. DEQ detected elevated levels of another toxic compound - hexavalent chromium - at the monitoring stations set up near Bullseye Glass.

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This carcinogenic form of chromium is most often emitted from industrial paint and chrome plating operations.

But DEQ laboratory manager, Brian Boling said Bullseye isn't using chrome, according to the company.

“There’s additional sources of hexavalent chromium,” Boling said.

Officials said the levels don’t pose a short-term health risk, but they also don’t know where it’s coming from.

“Understanding wind direction and wind patterns will allow us to see what’s going on, and try to identify potential sources, and what can be done – along with, is this just the fluctuation in the data, and we see it drop back down,” Boling said.

Monitors near the Uroboros glass plant in North Portland did not show elevated hexavalent chromium.