PITTSBURGH (KDKA) -- In June 2013, Glen Brunken was meeting a friend for lunch.
But that lunch never happened. The 69-year-old retired art professor from Slippery Rock University fell through the glass door of Bob's Sub and Sandwich in Slippery Rock.
The glass door shattered. Brunken suffered cuts to his head and neck and died after being rushed to the hospital. The coroner listed the cause of death as "accidental sharp force injury to the neck."
"Every encounter with Glen was a joyous encounter," says Gary Jurysta, a long-time friend of Brunken's.
Jurysta's wife was meeting Brunken for lunch the day he died.
"As she was waiting for him, she heard the glass break and she immediately rushed over to help him and she couldn't stop the bleeding," Jurysta said.
In a lawsuit filed by Brunken's family against the sandwich shop, Brunken's widow, Cynthia Brunken, alleges that the tragedy could have been prevented if the restaurant had safety glass in the front door instead of annealed glass.
"Because it wasn't safety glass, a piece of glass cut him right through the neck, a major artery and he bled to death. It just shouldn't have happened," says Jurysta.
"Every few days there is an accident of this sort somewhere," says Mark Meshulam, an international glass and window safety expert.
Meshulam says annealed glass can be very dangerous because when it breaks, it creates shards of glass that can cut like knives, and it can break in the blink of an eye. He is often called as an expert witness when a family sues after an accident.
"I'm seeing people falling through store fronts getting seriously cut up or killed," he said. "I have seen people falling through windows because they leaned against the glass and the glass gave way suddenly."
LaShawna Threatt died after the window in her hotel room at the W Atlanta Midtown shattered. She and a friend had leaned on it, according to witnesses in the room.
And there's the case of Michael Racky outside Chicago. He leaned on a storefront window which gave way. He suffered serious lacerations and died.
These cases, along with the Brunken case, all involved annealed glass.
KDKA asked Meshulam to show us the difference between annealed glass and tempered safety glass.
At Farabaugh Engineering and Testing in McKeesport, we used a weighted bag to simulate a 100 pound boy running full speed into the glass. With annealed glass, the window shattered and dropped shards of glass like daggers.
"This is dangerous. It's razor sharp," says Meshulam.
But when we did the same experiment with tempered safety glass, the weighted bag just bounced off of glass.
"It's four to five times stronger than annealed glass," says Meshulam.
When it does break, tempered glass breaks into little cubes.
"You can get cut up and bleed, but it's not going to be a life threatening injury," adds Meshulam.
While current building codes call for safety glass in new or renovated buildings -- older buildings are exempt.
We took Meshulam to Pittsburgh's popular South Side to see if we could find glass he deemed dangerous. It took us less than a minute. We found annealed glass with cracks in it. Meshulam says that is a serious hazard.
"If someone falls into this they are going to be seriously cut, it's not going to be pretty at all," he said.
Many of the storefronts did have safety glass. You can spot tempered glass because it will have a logo etched into the bottom or top corner of the glass.
Meshulam says the public should exercise a healthy dose of caution when around glass.
"The glass can go from looking relatively pristine to completely broken in an eye blink," he said. "So the person who is involved in this accident, they have no time to react whatsoever. Their life goes from normalcy to a shower of glass cutting them in a fraction of a second."
We contacted the City of Pittsburgh regarding the storefronts on the South Side with broken glass. The head of the Bureau of Building Inspection said the owners of the buildings are being put on notice to fix their broken windows.
The owner of Bob's Sub and Sandwich Shop had no comment regarding the incident at the restaurant.
The annealed and tempered glass used in our story was donated by Diversified Lineal Systems: www.diversified-composites.com.
Testing of the glass was performed at Farabaugh Engineering and Testing: www.fetlabs.com.
Glass expert Mark Meshulam: www.chicagowindowexpert.com.
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