By Katie Kerwin McCrimmon
Rocky Mountain News 

DENVER — Independent tests show that breathing masks were functioning properly when two Denver firefighters had to be rescued after being unable to breathe at fires last year.

Both men survived, but a colleague who collapsed in a third blaze died.

Fire officials said they hope the latest results will allay fears on the Denver force that the masks are faulty.

The National Institute for Occupational Safety and Health (NIOSH) said this week the masks the surviving firefighters wore were working. NIOSH had earlier determined the mask also was working when the third firefighter died.

Denver firefighters use masks made by Scott Health & Safety.

In May 2006, Billy Green collapsed while fighting a fire in south Denver. He recovered and is now back at Station 21.

Days later, Lt. Rich Montoya, a veteran firefighter near retirement, died after collapsing at a north Denver fire.

The exact cause of his death was unclear, but the department's report found that Montoya got trapped under a mattress in a room cramped with furniture. His mask was knocked off his mouth, and he suffered brain damage after breathing noxious fumes.

In October, Sean Wendt had to be hospitalized after having trouble breathing while fighting a blaze in Park Hill. He pushed his mask away from his face. Wendt is back at the training academy.