Silica Exposure Prevention in Construction

By Tim Janis, Contributor

Construction workers are at risk when exposed to silica, which is a naturally occurring mineral found in many materials used in construction. When silica is disturbed, small, respirable particles are created that can be inhaled into the lungs of nearby workers.

Sand, concrete, brick, block, stone, and mortar contain crystalline silica. Very small particles, typically 100 times smaller than ordinary sand found on beaches or playgrounds, are generated by high-energy operations, such as cutting, sawing, grinding, drilling, crushing, and blasting. Long-term exposure to these particles can cause serious health problems, including lung cancer, silicosis, kidney disease, and chronic obstructive pulmonary disease (COPD).

The construction standard for respirable crystalline silica (29 CFR 1926.1153) requires employers to limit worker exposure to respirable crystalline silica and to take other steps to protect workers.

When Does the Standard Apply?

Some employees in the construction sector perform tasks involving only occasional, brief exposure to respirable crystalline silica that is incidental to their primary work. These workers may include carpenters, plumbers, and electricians who occasionally drill holes in concrete or masonry or perform other tasks that involve minimal exposure to respirable crystalline silica.

When employees perform tasks that involve exposure to respirable crystalline silica for a very short period of time, these exposures are likely to be below 25 μg/m³ (micrograms of silica per cubic meter of air) as an 8-hour time-weighted average (TWA). For example, it can be reasonably anticipated that a user of a handheld drill for 15 minutes or less per 8-hour day will not exceed the standard’s threshold, resulting in it not being applicable.

If, however, exposure levels are at or above the permissible exposure limit (PEL) of 25 μg/m³ over an 8-hour TWA, employers must comply with the construction standard by taking steps to minimize worker exposure.

Adhering to the Silica Standard

To comply, employers can either use a control method laid out in Table 1 of the construction standard, or they can measure workers’ exposure to silica and independently decide which dust controls limit exposures in the workplace to the PEL.

When using Table 1, employers are responsible for implementing a silica control method, such as the application of water to keep dust from getting into the air or using a vacuum collection system. These are common engineering controls. In some operations, respirators may be required. Employers who follow Table 1 correctly are not required to measure workers’ exposure to silica and, therefore, are not subject to the PEL.

If the work task does not match any of the 18 most common construction activities listed in Table 1, or if employers do not fully implement any of the control measures in Table 1, then a formal dust sampling must be completed in order to determine the amount of silica exposure. Employers are required to protect workers from respirable crystalline silica exposures that are above the level included in the standard. Oftentimes, personal protective equipment (PPE) is insufficient; an engineering control must be implemented in addition to using respirators.

OSHA requires that all construction employers covered by the standard are required to:

• Establish and implement a written exposure control plan that identifies the tasks involving exposure and the methods being used to protect workers, including procedures to restrict access to work areas where high exposures may occur.
• Designate a Competent Person to implement the written exposure control plan.
• Restrict housekeeping practices that expose workers to silica, such as dry sweeping or the use of compressed air without a ventilation system to capture dust.
• Offer medical exams, including chest X-rays and lung function tests, every three years for workers who are required by the standard to wear a respirator for 30 or more days per year.
• Train workers on the health effects of silica exposure, workplace tasks that can expose them to silica, and ways to limit exposure.
• Keep records of workers’ silica exposure and medical exams.

Additional information on OSHA’s silica standard can be found at osha.gov/silica.

Practical Prevention Tips

Following these practical procedures helps to prevent silica exposure during construction:

• Use engineering controls – which are the most effective way to prevent silica exposure – by wet sawing, installing dust collection systems, and ventilating local exhaust.
• Provide PPE, such as respirators, while remembering that PPE should not be used as a substitute for efficient engineering controls.
• Adopt healthy work practices for jobsite maintenance, including wet sweeping and applying water to dust-filled areas.

Tim Janis is Safety Training Specialist, Chicagoland Construction Safety Council (buildsafe.org).