Sarcoidosis is a multisystem immune-mediated disease. Airborne sources of antigens interact with immune defenses to create the granulomatous immune response in tissues. Granulomas are one form of delayed hypersensitivity reactions in tissues that take weeks or months to form and leave permanent scars. Some chronic infections such as tuberculosis and fungal infections produce granulomas. Sarcoid granulomas appear in the lungs and the lymph nodes that receive antigens from the lungs. Granulomas also appear in the skin and other organs.
Occupational clusters have been reported in health-care workers, US Navy enlistees, teachers, automobile manufacturers, retail industry workers and firefighters. Granulomatous diseases have been associated with exposures to organic dusts, metals, molds, chemical dust, silica, wood dust, and smoke. Izbicki et al followed 26 fire fighters who developed sarcoidosis after exposure to World Trade Center dust during the collapse and rescue/recovery efforts. A large number of exposed citizens developed upper respiratory symptoms, especially chronic cough and increased asthma attacks from inflammation in the upper and lower respiratory tracts but only a small number developed granulomatous disease.
More than 400 substances were found in samples of WTC dust in four main categories: (1) particulate matter (calcium carbonate and silica) and fibers (chrysotile asbestos, fibrous glass, gypsum); (2) organic chemical pollutants, including polycyclic aromatic hydrocarbons, other hydrocarbons (naphthalene, fluorine, polychlorinated biphenyl, dibenzo-p-dioxins, and diphenyl ethers), benzene, and freon; (3) gases, such as carbon monoxide, hydrogen sulfide, combustion byproducts from WTC fires that burned until mid-December 2001, and diesel exhaust fumes from the vehicles/machinery employed during the rescue recovery effort; and (4) heavy metals. Some of these substances had already been associated with granuloma formation.
Gabriel Izbicki, Robert Chavko, Gisela I. Banauch; et al World Trade Center "Sarcoid-Like" Granulomatous Pulmonary Disease in New York City Fire Department Rescue Workers. CHEST 2007;131(5):1414-1423.