Monitoring

Employers must assess exposure of each employee who may be in contact with respirable crystalline silica at or above the action level of 25 μg/m3 over an eight-hour day.

Employers can either use a control method laid out in Table 1 of OSHA 29 CFR 1926.1153, or they can measure workers' exposure to silica and independently decide which dust controls work best to limit exposures in their workplaces to the PEL.

Table 1 matches 18 common construction tasks with effective dust control methods, such as using water to keep dust from getting into the air or using a vacuum dust collection system to capture dust. In some operations, respirators may also be needed. Employers who follow Table 1 correctly are not required to measure workers' exposure to silica from those tasks and are not subject to the PEL.

Employers who do not fully implement the control methods outlined in Table 1 must implement an alternative process, as follows:

• Determine the amount of silica that workers are exposed to if it is, or may reasonably be expected to be, at or above the action level of 25 μg/m3, averaged over an eight-hour day.
• Protect workers from respirable crystalline silica exposures above the PEL of 50 μg/m3, averaged over an eight-hour day.
• Use dust controls and safer work methods to protect workers from silica exposures above the PEL.
• Provide respirators to workers when dust controls and safer work methods cannot limit exposures to the PEL.

To learn more about Construction Silica visit our Construction Silica Safety Online Training web page.