DENVER -- Those "puffer" airport security screening machines being used at 37 airports, including Denver International Airport, are now going to be scrapped because they've been proven ineffective, according to a report Thursday.

The puffer machines, or explosives trace portals, were designed to detect explosives. The machine blew several puffs of air on travelers and analyzed it for any residue. This all occurred within 20 seconds.

Only select passengers at DIA went through the puffer. The machines were installed at DIA in May 2006.

The program cost $36 million, but is being scuttled because the machines proved unreliable at airports.

TSA bought 207 puffers starting in 2004. Ninety-four were installed in 37 airports across the country including three at DIA. The other 113 machines stayed in storage.

Dirt and humidity in airports led to frequent breakdowns, officials said. The TSA has removed 60 puffers and will pull the rest, although the timeline is unclear and no deadline has been set.

So was the program a waste? Aviation security expert Jeff Price said no.

"Was it a waste? I'd say it was a technology test that cost a lot of money," Price said. "It wasn't proven technology in an airport environment and it's not surprising they had a high breakdown rate. Plus, newer technology is available."

As a replacement, the TSA is installing body scanners that create images of passengers through their clothing. The TSA plans to have 250 scanners next year, costing $170,000 each, its 2010 budget shows.

Frequent flyers said they are a little wary of the body scanners but don't mind more money being spent on security.

"I don't think any amount of money in the name of safety is cool," said Karen Santilla. "But you do have to use new technology to see if it works."