Sandblasting and Silicosis

Outline of this article, Sandblasting and Silicosis:

1. What Is Silicosis?
2. Description and Uses of Abrasive Blasting
3. Types of Silicosis
4. Symptoms of Silicosis
5. Occupations Most at Risk
6. Common Applications of Abrasive Blasting
7. Silicosis Statistics
8. Preventing Silicosis
9. Safety Measures
10. Can You Get Silicosis from One Exposure?
11. Treatment for Silicosis
12. Substitutes for Silica Sand in Abrasive Blasting
13. Regulation and Compliance Schedule

What is Silicosis?

Silicosis (also known as “Potter’s Rot”) is an occupational lung disease caused by breathing free crystalline silica dust or other mineral dust. The dust settles into the lungs, causing inflammation, then scarring, as the lung tissue create fibrous nodules around the silica particles.

Workers who develop silicosis are more susceptible to other lung diseases, such as tuberculosis and lung cancer.

Description and Uses of Abrasive Blasting

Abrasive blasting, commonly known as sandblasting, is the process of projecting a high-velocity stream of abrasive particles at a surface, usually with compressed air or water.  At one time, the use of silica sand in abrasive blasting was very widespread. Because of this, people who work in the abrasive blasting industry became known as sandblasters.

Silica sand was phased out from abrasive blasting when the health risks became widely known. Exposure to crystalline silica, which can be inhaled, and settles in the lungs, can cause silicosis and other respiratory disease.

Types of Silicosis

There are three main types of silicosis:

• Chronic silicosis, which appears 10 to 30 years after exposure to crystalline silica at low exposure levels. This can affect the upper lungs and sometimes cause extensive scarring.
• Accelerated silicosis, which occurs within five to ten years of high-level exposure to silica dust.
• Acute silicosis, which occurs within a few weeks to five years within the initial exposure. With acute silicosis, cough, weight loss, and fatigue are common symptoms.

Depending on the level of exposure, silicosis can develop within a few weeks to decades after the first exposure to crystalline silica dust. When workers breathe in silica dust, they inhale tiny particles of the mineral silica. As the lungs grow fibrous nodules around the silica particles, scar tissue and fluid builds up in the lungs. This lung scarring makes it difficult to breathe, and leads to gradually more dire symptoms.

Symptoms of Silicosis

Silicosis my go unnoticed in its earliest stages. With continued exposure to silica dust, you may experience:

• Shortness of breath
• Blueish tinged skin
• Cough
• Nail abnormalities
• Rapid breathing
• Fever
• Chronic fatigue
• Loss of appetite
• Weight loss
• Chest pain

Eventually, silicosis can lead to respiratory failure, and death. Silicosis makes a person more prone to develop other respiratory diseases such as tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD), compensatory emphysema, lung cancer, and pneumothorax.

As time goes on, and as lung capacity decreases, silicosis sufferers may need oxygen support to help them breathe.

Occupations Most at Risk

According to the Center for Disease Control, the industries that pose the greatest potential risk for worker exposure to silica particles are:

• Construction
• Mining
• Sandblasting
• Agriculture
• Ceramics
• Detergent Manufacturing
• Ship Building
• Railroad Construction
• Abrasive Manufacturing
• Foundry Work
• Stone Crushing or Stone Cutting
• Quarry Work and Rock Drilling
• Masonry or Cement Work
• Demolition
• Glass Manufacturing
• Plumbing
• Painting

Common Applications of Abrasive Blasting

Some types of work dependent on abrasive blasting:

Finishing metal surfaces, or removing residue from tools, aluminum wheels, or car parts

• Removing debris and irregularities from foundry castings
• Cleaning and removing paint from ship hulls, stone buildings, metal bridges, and other metal surfaces
• Finishing tombstones,
• Etching or frosting glass.
• Sandblasting denim jeans to make them look worn

Silicosis Statistics

Globally, silicosis resulted in 46,000 deaths in 2013. This number is down from 55,000 silicosis related deaths in 1990.

About 2 million workers in the United States may be potentially exposed to silica dust each year.

A 1992 NIOSH study shows several examples of death caused by silicosis in the late 1980s and early 1990s. In almost all these cases, silica dust was inhaled by workers because they used proper supplied-air respirators during active sandblasting, but only a disposable filter mask during the rest of their work shifts. Silica dust remains in the air directly after sandblasting and can still be inhaled into the lungs.

Preventing Silicosis

OSHA, the Occupational Safety and Health Administration has suggestions for employers to help prevent silicosis. It requires awareness and planning to reduce risk for everyone in the workplace. Here are some steps employers can take:

• Inspect work areas to determine the source of silica dust
• Isolate processes that produce silica dust
• Suppress airborne crystalline silica dust with moisture or water
• Use engineering controls such as blasting cabinets and local exhaust ventilation to reduce spread of silica dust.
• Avoid using compressed air for cleaning surfaces in the open work area.
• Use non-crystalline silica abrasives for sandblasting
• Conduct regular inspections of the ventilation systems, about every three months
• Use approved air-supplied respirators
• Offer workers periodic medical exams, including a chest x-ray and pulmonary function tests
• Train employees on correct personal hygiene and work habits to help reduce their risk of silica exposure
• If silica is found in large quantities in the workplace as a supply, store it in airtight containers
• Educate and train all employees about the dangers of breathing silica dust
• Refrain from smoking. When cigarettes are combined with exposure to silica dust, the odds of severe lung disease and damage increase drastically.

You can find more information at http://www.osha.gov/Training/Silicosis.html

Safety Measures

There are preventative steps and control measures that workers can take to reduce the risk of developing silicosis.

• Wearing personal protective equipment (PPE): Use a respirator, face mask, or protective clothing when working with, or nearby, silica dust.
• Contain the abrasive blasting in a properly contained, ventilated, and filtrated unit, such as a blast room for very large objects, or a blast cabinet for more manageable objects.
• If you blast large objects in a blast room, outdoors, or in an enclosed space, change into clean clothing after blasting (because the dust settles on your clothes).
• Wash your face and hands immediately after working with silica or close to silica dust.
• Use water spray (dustless blasting) and proper ventilation whenever possible.
• Do not eat, drink or smoke near crystalline silica dust.
• Wash hands and face before eating, drinking or smoking away from exposure area.

Blast cabinets are one of the safest ways to conduct abrasive blasting. This is because the blast operator stands outside the blasting enclosure and operates the blast gun using rubber gloves that go inside the enclosure. As with any abrasive blasting, proper dust collection and ventilation is important for worker safety.

Can You Get Silicosis From One Exposure?

Although developing silicosis from one exposure is rare, it is still possible. The degree of risk depends on how much dust the worker is exposed to, and how often they are exposed. The higher your exposure to silica dust, the greater the risk. As the degree of exposure increases, your lung’s ability to defend against dust settling into the lungs decreases. If a worker is exposed to a high level of silica dust one time, and that dust settles in their lungs, it is possible for them to later develop silicosis.

Treatment for Silicosis

Once silicosis has developed, reversing the damage to the lungs is impossible. Usually, the only way to live out a normal life is to get a lung transplant.

Some of the conventional treatment options that exist are medication, steroid, and oxygen therapy. If you have developed silicosis, you should quit smoking immediately, as the chances of developing with lung cancer increase drastically.

The American Lung Association has a resource page on living with silicosis here: http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/silicosis/living-with-silicosis.html

Substitutes for Silica Sand in Abrasive Blasting

There’s a wide assortment of abrasive blast media options that can take the place of silica sand.  Some popular options include crushed glass by Glass Blast (no detectable free silica), glass beads made from soda lime glass, plastic media, organic abrasives (walnut shell or corn cob), sodium bicarbonate (soda blasting), coal slag (usually contains less than 1% free silica), or steel shot. Always consult the manufacturer’s MSDS for silica information.

Regulation and Compliance Schedule

As of March 2016, OSHA mandated that companies must provide certain safety measures for employees who work with silica or around silica, to prevent silicosis, lung cancer, and other silica-related diseases.

Key Parts of the new OSHA Standards

• Permissible exposure limit (PEL) for breathable crystalline silica must be no more than 50 micrograms per cubic meter of air, (averaged over an 8-hour shift).
• Engineering controls (such as water or ventilation) must be in place to limit worker exposure to the PEL.
• Employers must provide respirators when engineering controls cannot adequately limit exposure.
• Companies must limit worker access to high-risk silica exposure areas.
• Workplaces must create a written exposure control plan.
• Employers must provide medical exams to monitor highly exposed workers.
• Companies must train workers about silica risks and how to prevent respiratory diseases caused by workplace silica.
• Information about lung health must be provided in the workplace.

Compliance Schedule

The standards in the final ruling took effect on June 23, 2016. Industries have between one and five years to comply with most workplace requirements. This is the schedule for compliance in the following industries:

Construction / Contractors – June 23, 2017.

Maritime – June 23, 2018.

General Industry – June 23, 2018.

Fracking – June 23, 2018, for all provisions except Engineering Controls, (compliance date: June 23, 2021).