Silicosis: Exposure History, Respiratory Care and Occupational Prevention

Silicosis is a fibrotic lung disease caused by inhaling respirable crystalline silica (quartz or cristobalite). Alveolar macrophages engulf the silica particles and release cytokines, reactive oxygen species and other mediators that drive inflammation and fibrosis. The result is silicotic nodules, which can coalesce into large conglomerate masses called progressive massive fibrosis (PMF), reducing lung volumes and gas exchange. The scarring is permanent, but the disease is preventable. Three forms are described. Canadian and US sources give slightly different time frames, so both are shown: - Chronic silicosis is the most common form. CCOHS describes onset after 15 to 20 years of moderate to low exposure; the OSHA medical-surveillance appendix describes onset after at least 10 years of exposure. It is slowly progressive. - Accelerated silicosis follows high exposure. CCOHS states it can be detected after 1 to 10 years; OSHA states it generally occurs within 5 to 10 years. Its course is rapid and severe. - Acute silicosis (silicoproteinosis) follows extremely high exposure and can develop within a few months to 2 years (CCOHS and OSHA). The alveoli fill with...