NIOSH Findings on Worker Exposures to Silica: In cooperation with oil and gas industry partners, NIOSH collected 116 full shift air samples at 11 hydraulic fracturing sites in five states (Arkansas, Colorado, North Dakota, Pennsylvania, and Texas) to determine the levels of worker exposure to silica at various jobs at the worksites. Many air samples showed silica levels for workers in and around the dust generation points above defined occupational exposure limits.ⁱ Of the 116 samples collected: 47% showed silica exposures greater than the calculated OSHA PEL. 9% showed silica exposures greater than the NIOSH REL of 0.05 milligrams per cubic meter (mg/m3). 9% of all samples showed silica exposures 10 or more times the PEL, with one sample more than 25 times the PEL. 31% of all samples showed silica exposures 10 or more times the REL, with one sample more than 100 times the REL. Determining worker exposure levels is important for selecting the right type of control measures, including engineering controls and respiratory protection. For example, half-face respirators are not protective for silica levels over 10 times the exposure limit. NIOSH found that sand mover and blender operators, and workers downwind of these operations (especially during hot loading), had the highest silica exposures. Workers upwind and not in the immediate area of sand movers (sand delivery truck spotters) also had exposures above the NIOSH REL, possibly from the dust created by traffic at the well site. Worker and area samples collected in enclosed but non-filtered cab vehicles (e.g., chemical and blender trucks) were above the REL, even when spending most of the day in the cab. Worker and area samples collected in enclosed vehicles with air conditioning and filtration (e.g., data vans) had silica exposures below the NIOSH REL. What are the symptoms of silicosis? Silicosis is classified into three types: chronic/classic, accelerated, and acute. Chronic/classic silicosis, the most common type, occurs after 10 - 20 years of moderate to low exposures to respirable crystalline silica. Symptoms associated with chronic silicosis may or may not be obvious; therefore, workers need to have a chest x-ray to determine if there is lung damage. As the disease progresses, the worker may experience shortness of breath when exercising and have clinical signs of poor oxygen/carbon dioxide exchange. In the later stages, the worker may experience fatigue, extreme shortness of breath, cough, and, in some cases, respiratory failure. Accelerated silicosis can occur after 5 - 10 years of high exposures to respirable crystalline silica. It is similar to chronic silicosis, but progresses more rapidly. Acute silicosis occurs after only a few months or a few years following exposures to extremely high levels of respirable crystalline silica. Symptoms of acute silicosis include rapidly progressive and severe shortness of breath, weakness, and weight loss. Though much less common than other forms of silicosis, acute silicosis nearly always leads to disability and death. Several OSHA standards and directives cover operations that may expose workers to silica, including: (a) Air Contaminants (29 CFR 1910.1000); (b) Hazard Communication (29 CFR 1910.1200); (c) Respiratory Protection (29 CFR 1910.134). OSHA's Directive CPL 03-00-007, titled National Emphasis Program - Crystalline Silica, has detailed information on silica hazards, guidelines for air sampling, guidance on calculating PELs for dust containing silica, and other compliance information. See more from topic source: https://www.osha.gov/html/a-z-index.html