OSHA and the National Institute for Occupational Safety and Health (NIOSH) have issued a hazard alert on ensuring that employers in hydraulic fracturing operations take appropriate steps to protect workers.

The alert follows a study by NIOSH and industry partners of 11 sites in five states where hydraulic fracturing operations were taking place. NIOSH identified seven primary sources of silica dust exposure during fracturing operations and found that workers downwind of sand mover and blender operations: especially during hot loading: had the highest silica exposure.

The alert describes how a combination of engineering controls, work practices, protective equipment and product substitution, where feasible, along with worker training, can protect workers who are exposed to silica. Engineering controls and work practices provide the best protection for workers, says OSHA. According to the alert, transporting, moving, and refilling silica sand into and through sand movers, and along transfer belts and into blender hoppers, can release dust into the air that workers breathe containing up to 99% silica.

Respirable silica is a hazard common to many industries and industrial processes. Workers who breathe silica day after day are at greater risk of developing silicosis, a disease in which lung tissue reacts to trapped silica particles, causing inflammation and scarring, and reducing the lungs' ability to take in oxygen. Silica also can cause lung cancer and has been linked to other diseases, such as tuberculosis, chronic obstructive pulmonary disease, and kidney and autoimmune disease.

View the hazard alert