At least 1.7 million U.S. workers are exposed to respirable crystalline silica in industries and occupations including construction, sandblasting, and mining, according to the U.S. Centers for Disease Control and Prevention.

More specifically, workplaces and jobs with risks include foundries, industries that have abrasive blasting operations, paint manufacture, glass and concrete product manufacture, brick making, china and pottery manufacture, manufacture of plumbing fixtures, and many construction activities.

 Silicosis, an irreversible but preventable disease, is the illness most closely associated with exposure to the material, which also is known as silica dust. Chronic silicosis results from exposure over long periods of time (10 years or more). Exposure to high levels of respirable crystalline silica causes acute or accelerated forms of silicosis that are ultimately fatal, according to OSHA.

A drawn-out standards update

OSHA has been working on a new standard for protecting workers against silica exposures since 2003. OSHA’s current permissible exposure limit for general industry is based on data more than 40 years old, dating back to a voluntary ACGIH© standard set in 1968 (PEL = 10 mg/cubic meter as respirable  dust). The current OSHA PEL for construction and shipyards is derived from ACGIH’s 1970 Threshold Limit Value (TLV) that is based on particle counting technology now considered obsolete, according to OSHA.

A NIOSH Hazard Bulletin issued in April 2002 indicated a significant risk of chronic silicosis for workers exposed to respirable crystalline silica over a working lifetime at the current OSHA permissible exposure limit (PEL), the Mine Safety and Health Administration (MSHA) PEL, or the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL).

Exposure studies and OSHA enforcement data indicate some workers continue to be exposed to levels of crystalline silica far in excess of current exposure limits.

To buttress its “statement of need” for an updated standard, OSHA states that the International Agency for Research on Cancer has designated crystalline silica as carcinogenic to humans, and the National Toxicology Program has concluded that respirable crystalline silica is a known human carcinogen.

OSHA’s recognition that a standard needs updating can come more than a decade before a new standard is issued. That’s what has happened in the case of silica. It is nine years and counting since the agency completed a small business impact report (2003), and initiated (2009) and completed (2010) a peer review of health effects and risk assessment. In a 2011 federal regulatory agenda, a proposal for a new silica standard was scheduled to be released by February, 2012. Prospects for the proposal to finally emerge in 2013 are iffy, according to OSHA-watchers in Washington, due to slow economic growth and claims that regulations kill jobs. And a proposal can be years away from a final standard being published.

Don’t wait on a standard

So what are EHS pros and exposed workers to do while standards-setting crawls along?

The Center for Construction Research and Training, in a 2011 Hazard Alert on silica, recommended three basic steps (in addition to OSHA’s preference for engineering controls):

Use water

Water can keep silica dust out of the air — and out of your lungs. Use tools with water attachments to control dust at the source. Water can also keep dust down during activities like sweeping and demolition. When working with concrete, mortar and some paints, water can be used as a suppressant while using a jackhammer, using a grinder or drill, or sawing or cutting. 

Use a vacuum

Use tools with vacuum attachments to capture the dust right where it starts. Dust is drawn into a hood or cover attached to the tool, through a hose, and into a HEPA-filter vacuum. The dust doesn’t get into the air — or your lungs.

Wear a respirator

When other controls don’t work well enough and your work creates more silica dust than OSHA allows, your employer is required to have a full, written respiratory protection program. Respirators can protect your lungs from dangerous dust.

The Center notes: Abrasive blasting and sandblasting cause extreme exposure. You must use a special Type CE respirator.

Know ill-health symptoms

In addition, states NIOSH, you should know the symptoms of silicosis, which is classified into three types:

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. Much less common than other forms of silicosis, acute silicosis nearly always leads to disability and death.

Fracking hazards

In recent news, NIOSH’s field studies show that workers may be exposed to dust with high levels of respirable crystalline silica during hydraulic fracturing. Hydraulic fracturing or “fracking” is a process used to “stimulate” well production in the oil and gas industry, according to a NIOSH Hazard Alert.

A booming business in parts of the U.S., fracking involves pumping large volumes of water and sand into a well at high pressure to fracture shale and other tight formations, allowing oil and gas to flow into the well. NIOSH recommends determining worker exposure levels to select 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, according to NIOSH.

Whenever respirators are used, you must have a respiratory protection program that meets the requirements of OSHA’s Respiratory Protection Standard (29 CFR 1910.134). This program must include proper respirator selection, fit testing, medical evaluations and training.

If respirators are provided, use at least a NIOSH-approved N95 respirator, according to NIOSH. If the silica level is more than 10 times the PEL, a half-face respirator is not protective and a respirator that offers a greater level of protection (e.g., a full-facepiece respirator, which will protect workers at silica levels up to 50 times the PEL) must be used. Full-face powered air-purifying respirators (PAPR) provide more protection than half-face air-purifying respirators. In general, workers find PAPRs to be more comfortable, states NIOSH.