By Brian Maass

DENVER (CBS4)– The National Institute for Occupational Safety and Health (NIOSH) has issued a nationwide alert to fire departments across the country following last July’s death of Denver firefighter John Whelan.

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The safety advisory concerns translucent corrugated roof panels, the same kind of panel Whelan fell through, leading to his death.

“We want to raise awareness,” said Lieutenant Commander Corey Butler, with the U.S. Public Health Service, which issued the alert in November. “It’s very serious, hence the urgency for getting this information out.”

On the night of June 28, 2015, Whelan was sent on to the roof of a north Denver warehouse following a small dumpster fire adjacent to the warehouse. In the darkness, Whelan, 46, stepped through a translucent roof panel and fell 17 feet. He died July 15.

A CBS4 Investigation then revealed a nearly identical incident in Denver in 2012. In that case, DFD Lt. Joseph Duran was sent on to a similar roof in north Denver for what turned out to be a non-fire. Duran stepped through a translucent roof panel but did not fall all the way to the ground.

He managed to catch himself on the skylight and fellow firefighters pulled him back to safety. But information about that incident was never disseminated department-wide, to hopefully prevent a re-occurrence.

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The building where Whelan fell(credit: CBS)

The building where Whelan fell(credit: CBS)

Weeks after the CBS4 Investigation, NIOSH issued its national bulletin recommending that all fire departments immediately take action to reduce the risk of firefighters being injured or killed while operating on roofs with the same type of translucent panels.

The bulletin recommends that all firefighters are trained to recognize the translucent panels, and that policies and procedures are established to ensure firefighters do not walk or stand on the panels.

According to the NIOSH alert, “Incident commanders should strongly consider the risk benefit analysis of permitting rooftop operations on identified buildings. Firefighters may not be aware of and may not fully appreciate the hazards and risks associated with these panels.”

“It seems that some firefighters may not know that these panels exist,” said Butler.

As fire departments nationwide mull the NIOSH alert, the agency is preparing a full report on the death of firefighter Whelan. The agency says that report may be finalized and released around June. The Denver Fire Department has said it is investigating why information about Lt. Joseph Duran’s close call in 2012 was not widely shared.

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CBS4 Investigator Brian Maass has been with the station more than 30 years uncovering waste, fraud and corruption. Follow him on Twitter @Briancbs4.