CLEVELAND (AP) — The U.S. Environmental Protection Agency has begun cleaning up a Cleveland warehouse where as many as 3 million fluorescent lamps and 250 drums filled with PCB-contaminated lighting ballasts have been stored.

The agency said Wednesday that it was notified Feb. 13 about a fire at Fluorescent Recycling on Cleveland’s west side and provided technical help to firefighters concerned about the presence of mercury inside the building. The EPA says it detected mercury vapors and the presence of PCBs, a toxic organic chemical banned by the U.S. in 1979.

The EPA says the company operated as a transporter of spent fluorescent lighting waste.