The odor from the building at 1525 Stratford Ave. was almost overwhelming in the immediate neighborhood and could be smelled several blocks away.

The Fire Department closed Stratford Avenue for several blocks in both directions to vehicle and pedestrian traffic until late afternoon, citing potential health and safety risks.

The state Department of Environmental Protection will investigate today whether there are residual environmental or health concerns, DEP spokesman Dennis Schain said.

He said the ignited chemical was zinc peroxide, used in an oven at the company, which "can be dangerous and toxic under certain circumstances."

"We know it is a company that works with chemicals, some of which can be dangerous if they get into the environment," Schain said. "Any chemical that gets into the environment poses some risk to human health and resources."

A spokesman for Flow Polymers could not be reached for comment. The company's Web site states it also has offices in Cleveland and manufactures tire, automotive, wire and cable, pharmaceutical and industrial products.

Nearby business owners said they noticed the smoke and smell caused by the fire.

"I looked across the street and saw this mushroom cloud of smoke above the building and I knew it could be big trouble because they use toxic chemicals," said Zoning Commission Chairman Richard Fredette, owner of Elite Automotive Services, across from the chemical company.

"It smelled like a rubbery asbestos combination that made it hard to breathe, and that really concerns me because this has happened numerous times over the past few years," Fredette said. "I sent all my workers home immediately because the fumes were so overwhelming."

Fredette said that as a business owner and town official he would like to see an investigation into the blaze.

"The Fire Department and DEP should conduct some kind of investigation as to why this keeps happening and what kind of health threat these chemicals could be posing to our firefighters," Fredette said.

Fire officials said zinc peroxide and other materials were being used at Flow Polymers to heat chemicals when the mixture ignited at about 1:45 p.m. They said the fire was contained within the building in about 30 minutes.

While there were no apparent injuries, DEP officials will conduct tests to determine the extent of the health and environmental impact, Schain said.

Deputy Fire Chief John J. Cybart said 15 firefighters from two engine companies and a ladder company were dispatched to the scene and were backed up by Milford firefighters.

Assistant Fire Chief John Milne said the chemicals that burned are classified as Hazmat materials.

"It will be up to the DEP whether to conduct air-quality testing in the building or that neighborhood if they deem it necessary," he said.