"If there’s dust and debris laying in your air (conditioner), every time that comes on it’s stirring that dirt up into your living space or working space," Mammarelli said.

Interior Maintenance performs thousands of cleanings each year for residential and commercial customers from New York to Virginia, capitalizing on the recent market for professional cleaning services.

"It’s a surface in your home or facility that might be out of sight, out of mind, but it still gets dirty," said Matt Mongiello, who co-owns the company with his brother Chuck.

The company’s technicians crawl through the ducts in a special suit to vacuum out the filth or, for spaces too small for people, use mechanical equipment to do the job.

Mammarelli said what they find often boggles the mind. "We did a Philadelphia school in 2003 (where) we found basketballs and backpacks," he said, adding that he discovered an old newspaper reporting the selection of former Soviet leader Mikhail Gorbachev during a cleaning a few years ago.

Started in 1976 as a janitorial service by parents Charles and Maria Mongiello from their Ardmore home, Matt Mongiello said the business has grown to about 100 employees.

"We were one of the few contractors in the area that could do the large commercial work and then that helped us continually grow," said Matt Mongiello.

Its clients include National Aquarium in Baltimore, the Army’s Aberdeen Proving Ground, Delaware County Memorial Hospital, Temple University, GlaxoSmithKline and DuPont Co., Matt Mongiello said.

He said the company’s total sales eclipsed $3 million in 2005 and that he expects to exceed that this year. IMC also does high-surface cleaning for manufacturing plants, kitchen exhaust cleaning, power washing and inspection of heating, ventilation and air-conditioning systems.

Harry Young, director of buildings and grounds for Southeast Delco School District, acknowledged that IMC’s work is critical to a working environment.

"It’s highly important in today’s world when it comes to molds and mildews ’cause one of the primary places that it can develop is in ducts," Young said, noting that IMC cleans and sanitizes several of the district’s schools.

Duct cleanings for the average home range from $400 to $600 and commercial cleanings vary based on the size of the job, Matt Mongiello said.

"You’re getting your office or home cleaner air," Mammarelli said, "and you’re tremendously improving your air quality."

***OTHER INFO***