A union representing Metropolitan Transit Authority (MTA) workers in New York is claiming that MTA employees are being endangered by asbestos discovered in a bus depot, while the MTA says tests failed to find the hazardous substance.

The Transit Workers Union (TWU) Local 100 is reportedly demanding that employees who work in the Brooklyn building, which was built in 1858, be evaluated for asbestos exposure-related health problems. The union says employees found fabric containing asbestos in air vents at the building.

News reports say the MTA says testing has shown that the asbestos in the depot is not friable, meaning, it is not in a state in which it could crumble and release tiny fibers into the air. Inhalable asbestos fibers can cause asbestosis, mesothelioma and lung cancer. However, non-friable asbestos can become friable over time.

The New York Daily News reported yesterday that MTA management has known for years that the transit system’s depots harbored numerous hazards – including asbestos.

Because of its strength, thermal stability, electrical resistance and is non-flammability, asbestos was commonly used in public and commercial building constructed before the 1980's in the U.S. It was added to concrete, asphalt, vinyl materials in roof shingles, pipes, siding, wall board, floor tiles, joint compounds and adhesives.