Construction and silicosis: the new rule

by Sarah Said | September 7, 2018 9:35 am

by Nayab Sultan

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Conservative estimates from the World Health Organization (WHO) estimate 46,000 annual deaths from exposure to harmful levels of respirable crystalline silica (RCS) dust and progression to silicosis.

In the United States, it has been several decades since the first standards to regulate silica in the industry were introduced (1971), and some would argue updates are long overdue considering an estimated 2 million American construction workers are exposed to RCS dust in more than 600,000 jobsites. Another 300,000 workers in general industry, ranging from foundries, fracking, and brick manufacture, may be exposed.

Occupational Safety and Health Administration’s (OSHA’s) 29 Codes of Federal Regulations (CFR) 1926.1153, Respirable Crystalline Silica, commonly referred to as the “new silica rule” introduces requirements for all covered industries including construction where employers engaging in activities that create airborne RCS must follow specified or alternative exposure control methods. OSHA began enforcing the new silica rule for the construction sector in late 2017, and for other sectors in June 2018.

All dust is not the same
RCS is a naturally occurring substance found in stone, rocks, sand, soil with fly ash, asphalt, clay, brick, concrete, grout, tiles (clay and ceramic), some composite materials and metallic ores, as well as in shingles, mortar, plaster, drywall, and many products commonly found in construction projects across the United States. Figure 1 offers some examples, while Figure 2 gives a range of RCS commonly found in the industry.

RCS is harmful to health when it is inhaled deep into the lungs. The dust that is particularly harmful is smaller than a fine grain of sand. To put this into perspective, the size of a period is about 200 to 300 μm (7.8 to 11.8 mils) in diameter, whereas the RCS dust is about 5 μm (0.2 mils)—so small the particles cannot be seen with the naked eye.

If a person is exposed to high levels of RCS, harmful effects and onset of silicosis can start in as little as a few weeks, especially where exposed to particularly high grades of silica dust and with no or ineffective respiratory protective equipment (RPE).

There are less-harmful forms of silica dust (e.g. amorphous-form diatomaceous earth or silica gel) that are not recognized to lead to silicosis, lung cancer, or other known diseases commonly associated with RCS. However, it is possible to chemically change amorphous silica to RCS at temperatures above 1300 C (2372 F).

There are set standards regulatory authorities determine to be maximum levels of exposure before there is likely to be any significant harm. The new standard establishes an eight-hour permissible exposure limit (PEL) of 50 μg/m³ and an action level (AL) of 25 μg/m³.

The standard requires employers to limit workers’ exposure to harmful dust levels and take steps to protect workers and others who may be affected by their activities. Employers can refer to Table 1 of 29 CFR 1926.1155 for common construction tasks to which this standard applies. Employers can either adopt these guidelines or measure workers’ exposure to silica, and independently decide dust control measures to limit levels in their workplace below the revised PEL.

Employers who opt not to fully adopt guidelines to keep exposures as low as reasonably possible as stated in the OSHA standard can have their own alternative exposure control methods and must:

• determine the level of silica dust workers are exposed to (or may be reasonably expected) at or above the action level of 25 μg/m³ averaged over an eight-hour working day;
• protect workers from RCS exposures above PEL of 50 μg/m³ averaged over an eight-hour day;
• use dust control and safer work methods from exposures above the PEL; and
• provide suitable RPE to workers when dust levels and safe work methods cannot limit exposure to the PEL.

The new standard also requires employers to:

• develop a written exposure control plan (ECP) clearly identifying the tasks where exposure is possible and the methods to be adopted to protect workers, including measures to limit exposure to non-workers who may also be exposed to high levels of dust;
• designate a competent person to implement the company’s ECP;
• restrict housekeeping practices potentially exposing workers to silica dust such as use of compressed air without a ventilation system, taking work overalls home, or dry sweeping where clear alternatives are available;
• offer medical examinations in the form of chest x-rays and lung function testing every three years for workers who are required to wear a respirator for more than 30 days or more a year;
• train workers on silica awareness and the conditions and precautions required to protect their health and ways to limit exposures; and
• maintain accurate records of both silica exposures and medical examinations.

Implementing these rules requires an initial assessment of how much silica dust is produced by a company’s operations. If the levels fall below 25 μg/m³ then the company is not required to develop an ECP, undertake any suggested engineering controls, or conduct medical tests. This includes the issue of not being required to wear suitable respiratory protection, dampen dust, or use a vacuum.

There remains some controversy over these new silica rules, particularly about the burden these provisions may place on employers. Nevertheless, it is estimated the new rule will save more than 600 lives and prevent 900 new cases every year once its effects are fully realized.

Some argue the cost of implementing these rules in terms of technological limitations places too great a burden on contractors. Additionally, the maximum penalty of non-compliance of $12,675 for a serious breach and $12,675 per day past the abatement date for a failure to address a violation coupled with $126,749 for a repeated or willful violation is seen by some as too steep. A part of this concern also extended to subcontractors on sites where exposure may affect others not in their employment. It is anticipated the new rule will provide net benefits of about $7.7 billion annually, according to some industry sources.

So, we know the basics of the new silica rule but what is exactly is silica and what are the principles one needs to know to effectively address the exposure control methods?

What is silicosis?
Silicosis is associated with inflammation and scarring of the upper lobes of the lungs in the form of lesions. While symptoms related to asbestos may take between 10 and 50 years to manifest, the effects of silicosis can start within a short period, as seen in the Hawks Nest Disaster (Figure 3).¹ Individual susceptibility is based on factors such as amount of dust, its size, RPE worn, the individual’s overall health status, and whether the person is a smoker.

In acute form (i.e. short-term, severe, or sudden), the symptoms are typically bluish skin, breath shortness, coughing, and fever. It is not uncommon for this to be misdiagnosed as pulmonary oedema (i.e. water in the lungs), pneumonia, or tuberculosis. Symptoms can continue to develop even after exposure has stopped. Other conditions can also occur, such as bronchitis, lung cancer, or arthritis.

So how can construction professionals work safely without being harmed? If the threat of exposure to RCS cannot be eliminated altogether, then there are a few control measures that may work in keeping dust to relatively safe levels. To ensure compliance, the local safe systems of work need to be followed. Generally, they are based on the principles of occupational hygiene: assess, control, and review.

Assessing and controlling the risks
High dust levels at the jobsite are caused by one or more of the following:

• task—high-energy tools can produce a lot of dust in a very short period;
• work area—the more enclosed a space, the more the dust builds up (one should not assume dust levels will be low when working outside);
• time—the longer the work takes, the more dust there will be; and
• frequency—regularly doing the same work day after day increases the risks of exposure.

For specific activities where RCS could become airborne, separating the workers and the airborne materials can be a successful solution. In some cases, the means can be as simple as dousing the dust source with a water stream and standing upwind. Where possible, it is also important to specify materials that have less silica content or do not produce large volumes of dust.

Stopping or reducing the dust before work starts is also crucial for controlling the risks, and is consistent with the new silica rule. This might mean different materials (e.g. the right size of building materials reduces cutting or preparation), less-powerful tools, or other work methods.

Regardless, the most important action is to stop the dust getting into the air, and more critically into the breathing zone of the workers. There are two main ways of doing this effectively: water and on-tool extraction.

Water damps down dust clouds, but to be effective, this needs to be in a fine mist or deluge form at a steady volume rate. Simply dampening material beforehand may not be as effective.

On-tool extraction removes dust as it is being produced. This type of local exhaust ventilation (LEV) fits directly onto the plant, tools, and equipment. The “system” consists of several individual parts—the tool, capturing hood, extraction unit, and tubing. It important to use an extraction unit to the correct specification (i.e. H [high], M [medium], or L [low] class of filter unit), and without sweeping. An industrial vacuum cleaner with a high-efficiency particulate air (HEPA) filter should be employed.

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One size does not fit all: Thoughts on RPE
Before selecting RPE, there are various considerations ranging from the type to the duration of activities. Generally, it is far easier and more efficient to use engineering controls to protect a wider range of workers than ill-fitting RPE that may give a false sense of security and endanger the lives of wearers. (Water or on-tool extraction coupled with suitable RPE provides additional protection.)

The chosen RPE must be adequate for the amount and type of dust; it should have an assigned protection factor (APF), which is the level of protection a respirator can be expected to provide if it is functioning properly and the user is wearing it correctly. APF is scored via a number, allowing users to gage how much contaminant they are expected to inhale while wearing the respirator.
The APF is calculated by taking measurements of air samples simultaneously outside and inside the respirator as the worker continues the job. The general level for RCS dust is an APF of 40 based on the activity—this means the wearer only breathes 1/40^th of the amount of dust in the air.

The RPE must also be suitable for the job. Disposable masks or half-masks can become uncomfortable to wear for long periods, whereas powered air-supply RPE helps minimize this. When people are working for more than an hour, it is also important to consider whether the RPE is compatible with other items of protective equipment. Face-fit testing can ensure it is being worn correctly (ideally, anyone using tight-fitting masks will be clean-shaven), but RPE is the last line of protection.

The correct HEPA-type cartridge should be fitted to protect workers against silica dust exposure. In North America, this tends to be magenta or purple, but one should always refer to the manufacturer’s safety data sheet or follow recommendations based on findings of air-monitoring.

Reviewing the controls
Even with all the right controls in place, they must be checked to ensure they are working properly. This means:

• having procedures to ensure work is done in the right way;
• checking controls are effective (if the work still seems “dusty,” exposure monitoring should be considered);
• involving workers, as they can help identify problems and find practical solutions;
• maintaining equipment (e.g. following manuals, inspecting for damage, making repairs, replacing masks, storing and maintaining non-disposable RPE, and testing on-tool extraction systems); and
• supervising workers to ensure they use the controls provided, follow the correct work method, and attend any health surveillance where required.

Air monitoring
Personal or background air monitoring should be carried out to accurately determine the levels of dust generation at various positions in the worksite and the maximum level of worker exposure. Monitoring will enable the correct selection of dust control methods and respiratory protection. Regular air monitoring on existing and new work methods will help ensure in-place dust control methods remain effective and provide adequate protection for workers.

Health surveillance
A health surveillance program will be important to verify controls are protecting staff. The surveillance program should be under the direction of a suitable respiratory physician and can include pre-employment health screening and occupational history questionnaires to set a baseline.

Protective clothing
It is vital dusty clothes do not contaminate cars, homes, or other areas outside of the worksite. Workers should have disposable overalls or washable clothes to change into at the site. Before leaving, workers should shower if possible and then change into clean clothes without shaking these out. Workers should not be taking dusty clothing home to wash—this may expose family to harmful levels of RCS dust. There are documented cases of family members getting sick from indirect exposures to silica dust and asbestos.

Training
Workers should be provided with competency based training on silica dust awareness. This includes information about the health effects of exposure to silica dust, work practices to follow when silica dust is created at a worksite, and the appropriate use and care of protective equipment. It is vital to ensure workers actually understand rather than just sit through the talk.

Prevention is the best form of protection against silicosis and other illnesses, by either complete elimination of the silica dust hazard or introducing suitable dust-control strategies using dry air-filtering and water spray where dust emanates. Further, each worksite needs to have a comprehensive review of the hazards covering which technique is likely to be appropriate and establishing suitable and effective risk-control measures such as development of an ECP—required in most workplaces where high levels of dust are identified.

Conclusion
Based on current medical knowledge, silicosis is not considered to be curable although therapy can alleviate some of the symptoms. It can develop within a few weeks of heavy exposure and continue even years after exposure ceases. (Smoking can also exacerbate the symptoms.) In many cases, silicosis is considered asymptomatic—a person may not show classic signs of silicosis, which is one of the reasons why misdiagnosis is widespread. Prevention of exposure is the key.

Note
¹ In this incident from the 1930s, hundreds of construction workers died as a result of acute silicosis and associated conditions due to exposure of high levels of RCS dust while building a tunnel through sandstone-based rock with little (or no) respiratory protection.

Nayab Sultan is a researcher at Silicosis Research, and is currently pursuing his PhD in silicosis prevalence in North America. He holds M.Sc. and M.Phil. degrees in the science of occupational health, safety, and the environment. Sultan has nearly 30 years of experience in construction and engineering, and has worked as a subject matter expert to several organizations across the Americas. He can be reached via e-mail at nmsultan@gmail.com[3].

Source URL: https://www.constructionspecifier.com/construction-and-silicosis-the-new-rule/

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