Joseph King sent the letter from the union to Fire Chief Darryl Jones concerning Station 24 at South 18th and Carson streets.
Two other firefighters from the station are currently suffering from inoperable cancer, according to the letter.
"Pittsburgh firefighters believe that there should be an immediate survey/investigation into this engine house because of the many cases of cancer among those who have worked there," King said in the letter dated Monday. "Something is seriously wrong."
Jones told the newspaper that he the letter and that the fire bureau and administration would look into the matter.
"If what they're telling us is true, there's obviously a concern," he said.
The letter comes on the heels of a decision made on Saturday by Gov. Ed Rendell to veto legislation that would have expanded workers' compensation claims for firefighters diagnosed with certain types of cancer.
King said his letter to Jones wasn't timed with Rendell's veto and just wants to prevent firefighters at the station from contracting the disease in the future.
"The best I can do is to bring this to the attention of management, and see how they handle this," he told the newspaper. "I'm not trying to file (compensation) cases; I'm trying to stop this from happening anymore."
There are 40 firefighters stationed at the South Side firehouse, which was built in the late 1960s or early 1970s.
