What is the maximum permissible exposure limit (PEL) for crystalline silica dust in construction, as defined by OSHA?

The maximum permissible exposure limit (PEL) for respirable crystalline silica dust in construction, as defined by OSHA (Occupational Safety and Health Administration) in 29 CFR 1926.1153, is 50 micrograms per cubic meter of air (50 μg/m³) as an 8-hour time-weighted average (TWA). This means that a worker's average exposure to respirable crystalline silica over an 8-hour workday must not exceed 50 micrograms per cubic meter of air. Respirable crystalline silica refers to very small particles of silica that can penetrate deep into the lungs when inhaled, causing serious health problems such as silicosis, lung cancer, and other respiratory diseases. OSHA also establishes an action level of 25 μg/m³ as an 8-hour TWA. When worker exposure reaches or exceeds the action level, employers are required to implement specific control measures, such as exposure monitoring, medical surveillance, and employee training. If the PEL is exceeded, employers must take immediate steps to reduce worker exposure below the limit, using engineering controls (like wet methods or ventilation), work practices, and respiratory protection if necessary. Regular air monitoring is crucial to assess worker exposure levels and ensure compliance with the OSHA standard. For example, if a worker is cutting concrete for 8 hours and their average silica exposure is measured at 75 μg/m³, the employer is in violation of the PEL and must take corrective action.