When is silica a hazard for construction workers?

Materials that contain crystalline silica are not hazardous unless they are disturbed, generating small-sized particles that can get in your lungs (“respirable crystalline silica”).  For example, blasting, cutting, chipping, drilling and grinding materials that contain silica can result in silica dust that is hazardous for construction workers and others to breathe.

What construction materials contain silica?

Many common construction materials contain silica including, for example, asphalt, brick, cement, concrete, drywall, grout, mortar, stone, sand, and tile.

How much silica dust is too much?

It only takes a very small amount of the very fine respirable silica dust to create a health hazard.  Recognizing that very small, respirable silica particles are hazardous, OSHA regulation 29 CFR 1926.55(a) requires construction employers to keep worker exposures at or below a Permissible Exposure Level (PEL) of 50 µg/m³.  The American Conference of Governmental Industrial Hygienists has a lower non-regulatory Threshold Limit Value of 25 µg/m³.

What is silicosis?

Silicosis is a disabling, irreversible, and sometimes fatal lung disease. When a worker inhales crystalline silica, the lungs react by developing hard nodules and scarring around the trapped silica particles. If the nodules become too large, breathing becomes difficult and death can result.

I don’t know anyone with silicosis so why should I be worried?

Unlike a work-related injury where the effects are seen immediately, silicosis and other silica-related illnesses may not show up for many years after exposure.  The most common early symptoms are a chronic dry cough and shortness of breath with physical activity. There are three types of silicosis:

• Chronic silicosis, which usually occurs after 10 or more years of exposure to crystalline silica at relatively low concentrations;
• Accelerated silicosis, which results from exposure to high concentrations of crystalline silica and develops 5 to 10 years after the initial exposure; and
• Acute silicosis, which occurs where exposure concentrations are the highest and can cause symptoms to develop within a few weeks to 4 or 5 years after the initial exposure.

Silicosis is a progressive disease – meaning it continues to get worse, even when exposure to respirable silica has stopped.