Suncor Energy’s oil refinery is spewing 8.5 tons a year of invisible hydrogen cyanide gas over low-income north Denver neighborhoods, state records show.

Community groups in Globeville, Swansea and Elyria this week petitioned the Environmental Protection Agency to require Colorado health officials to set a limit that protects people and at least require Suncor to disclose emissions of the gas to local emergency responders.

CDPHE air quality control officials in January approved a change to Suncor’s air pollution permit that exempts the company from a federal requirement to disclose hydrogen cyanide emissions. The officials set an emissions limit of 12.8 tons a year — higher than the 8.5 tons Suncor reported it emits — for the purpose of letting Suncor use a legal loophole that lets companies with permitted limits avoid disclosure of those emissions, a state document shows.

This CDPHE action overrode objections by Adams County Commissioners, who raised health concerns and said transparency is vital for emergency crews to be able to respond to potential hazards.

“It’s absurd to think state health officials would even consider granting permits to pollute more. The state health officials are completely failing to protect these neighborhoods. And they are disregarding the cumulative impact of the many pollutants in the area,” Cross Community Coalition director Candi Cdebaca said.

“The ideal would be we aren’t letting them put that into the air at all, and if they are, we would know how to respond,” she said.

Hydrogen cyanide is a colorless gas smelling faintly of almonds that at high exposure levels attacks the brain and heart, causing rapid breathing, convulsions and loss of consciousness, according to the U.S. Agency for Toxic Substances and Disease Registry. Lower level exposures are linked to breathing trouble, headaches and enlarged thyroid glands. The Organization for the Prohibition of Chemical Weapons, established under the 1997 global Chemical Weapons Convention, classifies hydrogen cyanide as a chemical weapon.

Upwind of Denver, in Commerce City, Suncor emits the hydrogen cyanide from a fuel catalytic cracking unit that is part of the company’s crude oil processing. These units break down hydrocarbons to produce the gas and diesel that Suncor sells, a main source of fuels in Colorado and the region.

Suncor’s refinery is not the only refinery that emits hydrogen cyanide. The EPA has not set a federal limit for hydrogen cyanide, so fossil fuels companies have not been focused on reducing those emissions.

“Everyone who lives near Suncor, as well as Suncor employees, have been breathing hydrogen cyanide. If the state is going to set a limit for hydrogen cyanide, it needs to set a limit that protects public health,” said Earthjustice attorney Joel Minor, who filed the petition on behalf of north Denver residents.

“And we have these laws requiring disclosure for a reason,” he said. “People do have a right to know what they are breathing.”

EPA in its regulation of the nation’s oil refineries has focused instead on carbon monoxide, sulfur dioxide, particulates, nitrogen oxide, hydrogen sulfide and other pollutants. As a result, data on hydrogen cyanide is limited. CDPHE relied on data Suncor collected in 2015 to calculate hydrogen cyanide air concentrations around the refinery at 5 parts per billion, more than seven times higher than the EPA’s 0.7 ppb risk threshold, records show.

In Colorado, the only other apparent source of hydrogen cyanide pollution is a Goodrich Corporation plant in Pueblo where workers make aircraft parts. State records show this plant disclosing emissions of 942 pounds a year of hydrogen cyanide.

Suncor’s refinery is one of the largest sources of air pollution in metro Denver. State air quality regulators since 2013 have begun at least five cases against Suncor seeking penalties for emissions of sulfur dioxide and other toxic gases, and they’ve ordered Suncor to correct deficiencies.

In 2012, state regulators fined Suncor $2.2 million for violations related to benzene air pollution above limits from the refinery. In 2015, state regulators ordered Suncor to fix other pollution problems detected in 2013 and 2014. Suncor at one point negotiated a deal to avoid admitting law violations in return for paying a $214,050 administrative penalty.

The refinery sits on an 80-year-old industrial site near the confluence of Sand Creek and the South Platte River, just north of Denver. Suncor bought the refinery in 2003 from ConocoPhillps in a $150 million deal. Over the past 13 years, Suncor has spent $1.6 billion on the plant.

A malfunction triggered by an Xcel power outage in October 2016 produced an orange cloud and raised health concerns, prompting reverse-911 notification of residents. A company spokeswoman in the aftermath said no toxic chemicals had been detected in surrounding neighborhoods, but documents filed with state regulators revealed that the refinery belched 75,600 pounds of sulfur dioxide, 150 times higher than the state’s 500 pound threshold for launching an investigation.

EPA and CDPHE officials declined to discuss the hydrogen cyanide emissions.

But CDPHE officials, in a response to queries conveyed by an agency spokesman, defended their decision to set a 12.8 tons a year limit for hydrogen cyanide. Before, there was no limit, according to the responses by agency officials.

However, that limit is not based on any health criteria, the officials said.

“We have strengthened the regulation of (hydrogen cyanide) emissions by imposing a limit on these emissions and adding annual testing,” they wrote in an email, adding that “monitoring results will be publicly available.”

Why did CDPHE agree to change the Suncor refinery’s air pollution permit in January allowing gas emissions without public disclosure? “Suncor can request voluntary limits in their permit, and the (Air Quality Control) Division has the authority under its regulations to include these limits in their permit,” the CDPHE officials wrote.

Suncor officials declined to discuss the issue.

EPA officials did not respond to written queries but “will be reviewing and responding to the petition,” an agency spokesman said.

Two blocks from the refinery, north Denver resident Robin Reichhardt, 38, who has lived in the area for three years, worried about possible health harm.

He was near a school on the day of the malfunction that led to “shelter in place” orders. “I could taste it, taste that something was in the air,” Reichhardt said.

“We love our neighborhood, but this is one of the reasons why we would leave it. It feels like we’re always getting choked out. We’re just always feeling, have a cough, a lot of respiratory illness through the year that won’t go away,” he said. “We feel pretty impotent about it. We’re really concerned. We feel like there’s nobody. Who do we go to?”