Dealing with a dangerous and deadly dust
It can be one of the most dangerous things your workers can encounter on the jobsite—crystalline silica. From sandblasting to raw materials inside concrete, bricks, and tile, there are a number of possible exposures. But we can help you limit those risks.
OSHA estimates that around 2.3 million workers are exposed to crystalline silica in the US. Silica exposure can cause silicosis, lung cancer, and other respiratory and kidney disease. In June 2016, OSHA issued a new rule regarding occupational exposure to crystalline silica. According to OSHA the standard will save nearly 600 lives and prevent 900 new cases of silicosis each year.
Sources of exposure
Silica sand, the most common form of quartz, is in many different products. It’s used often in sand blasting since it’s cheaper than alternatives that are less hazardous. Silica sand and silica flour are common filler materials in many products like paints and plastics. Some other uses include:
- Abrasives (sand blasting) and polishing agents
- Extenders in paint, wood fillers, rubber, plastics, and soaps
- Molding agents in foundries
- Raw material in concrete, bricks, tile, and glass
Industries with potential silica exposure are wide ranging and include:
- Quarrying and mining
- Clay and pottery
- Paintings and coatings
- Dental laboratories
- Jewelry production
- Refractory products
- Cut stone products
- Hydraulic fracturing
Silicosis is the major health concern from exposure to crystalline silica. It creates nodules in the lungs. Silicosis typically occurs after 15–20 years or more of exposure to respirable crystalline silica. Chronic silicosis may go undetected for years in its early stages. If there’s coalescence of the nodules over time with the formation of large masses, the disease is then called progressive massive fibrosis, which reduces lung function. That leads to significant respiratory and systemic symptoms of shortness of breath, productive cough, chest discomfort, and weight loss.
Silica-induced lung disease can continue once exposure ends. The body's ability to fight infections may be overwhelmed by silica dust in the lungs, making workers more susceptible to certain illnesses, such as tuberculosis. As the lung capacity decreases, the heart works harder trying to make up for the loss of oxygen in the blood. This usually leads to death from heart failure. Studies have shown that exposure to crystalline silica can also cause lung cancer.
OSHA has established a Permissible Exposure Limit for respirable silica of 0.050 mg/m³ (milligrams per cubic meter of air) as an eight-hour Time Weighted Average (TWA). OSHA has also established an action level of 0.025 mg/m³ as a TWA. The American Conference of Governmental Industrial Hygienists has a recommended Threshold Limit Value for silica of 0.025 mg/m³ as an eight-hour TWA.
OSHA Respirable Crystalline Silica Standard 29 CFR 1910.1053 requires you to assess employee exposure to silica where employees are or may reasonably be exposed to silica above an action level.
Use exposure monitoring or objective data to determine the levels of exposure. You’ll need to collect air samples on each shift, for each job classification, and in each work area. Employees with the highest potential exposure must also be evaluated. If the initial monitoring indicates exposures below the action level, monitoring may be discontinued for those employees. If they’re above, monitoring will be done every six or three months, depending on how high levels are. Download the full document on this page for details on the specific levels and OSHA testing requirements.
You should notify employees within 15 days after your exposure assessment is completed and all affected employees should either be notified in writing or by posting the results where all can see. If results are high, you’ll also have to describe in writing what’s being done to reduce exposures, establish regulated areas, and place signs in the affected areas that read:
- Respirable crystalline silica
- May cause cancer
- Causes lung damage
- Wear respiratory protection in this area
- Authorized personnel only
Engineering and work practice controls
OSHA’s standard requires you to develop a formal written exposure control program. At a minimum, you have to:
- Describe the tasks where there’s exposure to crystalline silica
- Describe what engineering controls, work practices, and respiratory protection you’ve put in place for each task
- Describe the housekeeping methods used to limit exposure
You’ll have to have your program reviewed at least once a year and updated as necessary so it remains effective.
Where respiratory protection is used to control exposure, you have to create a respiratory protection program that meets the requirements of 29 CFR 1910.134.
The standard also requires that High Efficiency Particulate (HEPA) vacuums or wet methods be used to clean silica accumulations. Compressed air, dry sweeping, and dry brushing cannot to be used to clean clothing or surfaces contaminated with crystalline silica.
OSHA also requires you to set up a medical surveillance program for employees who may be exposed above the action level for more than 30 days a year. It starts with a baseline examination within 30 days of assignment and every three years after that. The medical surveillance program includes a work history, a physical examination, a chest X-ray, a pulmonary function test, TB test, and any other tests deemed appropriate by the medical provider. You’ll also have to provide the physician with:
- A copy of the OSHA Crystalline Silica Standard
- A description of the work being done that led to silica exposure
- The employee’s former, current, and anticipated exposure levels to crystalline silica
- Description of the personal protection equipment (PPE) used
- Any past medical monitoring records you have for the employee
Medical providers will then have to provide you a written medical report within 30 days, and include:
- The results of the medical evaluation and whether the employee is at risk from exposure to crystalline silica
- Recommendations regarding the use of respirators
- Recommended limits on exposure
- A statement on whether the employee should be examined by a specialist based on the chest x-ray
The medical provider also has 30 days to recommend examination by a specialist.
Communicating the danger
OSHA also requires you set up training to teach workers and others about the dangers of crystalline silica. That training should include the health risks and:
- Operations in the workplace that may result in exposure to silica
- Specific procedures and practices that limit exposure
- Details on OSHA’s silica standard
- What the medical surveillance program is and why it’s important
Keeping the records
You’ll also be expected to keep records of any exposure monitoring done, the medical surveillance, and employee training. Air monitoring records must show:
- Measurement date
- Task monitored
- Sampling and analytical method used
- Number, duration, and results of the samples
- Information on the testing laboratory
- Type of PPE worn by the monitored employees
Medical records should include the name and social security number of the employees, copies of the medical provider’s medical opinion, and copies of the opinions of specialists.
Of course, this is just an overview on crystalline silica exposures and is not intended to be a complete interpretation of the standard. There are more details for you to understand. Be sure to talk to your Safety Services representative for help on ways to help keep your workers safe while meeting all OSHA standards.