Equipment Type

OSHA Silica Standard Up for Debate

New regulations for controlling “respirable crystalline silica” have medical, technical, and economic implications for equipment owners working in certain environments

December 21, 2016

The Occupational Health and Safety Administration (OSHA), in June, 2016, issued a Final Rule regarding occupational exposure to respirable crystalline silica. The Final Rule includes two standards, one for “Construction,” which is the focus of our discussion here, the other for “General Industry and Maritime.” Compliance dates are June 2017 and June 2018, respectively. We’ll let OSHA explain the rationale behind the new standards, as published in the Federal Register.

“OSHA has determined that employees exposed to respirable crystalline silica at the previous permissible exposure limits [PELs] face a significant risk of material impairment to their health. The evidence in the record for this rulemaking indicates that workers exposed to respirable crystalline silica are at increased risk of developing silicosis and other nonmalignant respiratory diseases, lung cancer, and kidney disease.

Controlling Silica Dust on Road-Construction Jobs

In March 2015, the results of a collaborative study that included input from federal worker-safety agencies, national trade associations, labor unions, and milling-equipment manufacturers were published by the National Institute for Occupational Safety and Health (NIOSH). The document, “Best Practice Engineering Control Guidelines to Control Worker Exposure to Respirable Crystalline Silica During Asphalt Pavement Milling,” recommends that machines be designed to include ventilation controls, in addition to water sprays used to cool the cutting teeth. “Milling machines that adopt this well-designed dust-control approach have been shown to control worker exposures to respirable crystalline silica from asphalt milling operations,” says the report. (NIOSH publication 2015-105.)

“This final rule establishes a new permissible exposure limit of 50 micrograms of respirable crystalline silica per cubic meter of air (50 μg/m3) as an 8-hour time-weighted average in all industries covered by the rule. [The previous PEL was 250 micrograms.] It also includes other provisions to protect employees, such as requirements for exposure assessment, methods for controlling exposure, respiratory protection, medical surveillance, hazard communication, and recordkeeping.”

Respirable crystalline silica? We’ll share what we know. Oxygen and silicon are among the Earth’s most abundant elements. When the two come together as silicon dioxide (SiO2), or “silica,” the compound can take a number of forms—quartz being the most common, followed by cristobalite and tridymite. The molecular structure of silica can be either amorphous or crystalline, with the latter having its atoms and molecules arranged in a repeating three-dimensional pattern.

It’s the crystalline form that causes OSHA concern. Crystalline silica occurs naturally in any number of substances—sand, gravel, mineral ores, cement, and some types of soil—and when these substances are processed or disturbed by such actions as mining aggregate, milling pavement, sawing concrete, demolishing structures, or sanding drywall, for example, tiny airborne particles of crystalline silica are released. It’s this respirable dust that can be drawn into the lungs. OSHA estimates that 2.3 million workers are exposed to respirable crystalline silica—most (an estimated 1.85 million) engaged in some form of construction activity.

Not everyone’s happy

Release of the Final Rule has been cheered by some in the construction industry, “long overdue,” they say, but strongly opposed by others. Those who oppose the new ruling say that the former standard was doing a good job of protecting workers and that the new standard is based on out-dated health data; will create a substantial financial burden on companies affected by the new standard, especially smaller firms; and that air-sampling requirements (needed in some instances) are burdensome and can be unreliable. A number of industry groups, in fact, have initiated litigation against the new Final Rule.

Opponents of the new standard cite statistics from the Centers of Disease Control and Prevention (CDC) and the National Institute for Occupational Safety and Health (NIOSH) that show the incidence of death from silicosis has significantly declined under the former OSHA standard. Further, they say, the majority of silicosis-related deaths in the United States result from industries not under OSHA jurisdiction and that CDC data show few silica-related deaths in the construction industry. Stricter enforcement of the former standard, they say, would accomplish the intent of the new standard without what they see as added burdensome and expensive requirements.

OSHA responds: “Silicosis deaths have declined in recent years, but the problem remains serious. From 2005 through 2014, silicosis was listed as the underlying or a contributing cause of death on over 1,100 death certificates in the United States, but most deaths from silicosis go undiagnosed and unreported. Also, those numbers of silicosis deaths do not include additional deaths from other silica-related diseases such as COPD, lung cancer and kidney disease. While the number of silicosis cases has declined over the past several decades, it is still a very serious workplace health problem.”

Among those who favor the new standard are some who say that, in fact, the new standard is not tough enough—such as Harry Beaulieu, PhD, president of Industrial Hygiene Resources and a certified industrial hygienist and certified safety professional.

Beaulieu explains that when OSHA was created in the early 1970s, the agency initially borrowed standards from various organizations that specialized in promoting guidelines and best practices for their members. Among these groups, he says, was the American Conference of Governmental Industrial Hygienists (ACGIH), which had established occupational exposure limits for a wide range of compounds. In 1971, says Beaulieu, OSHA locked into law the ACGIH exposure limits, called “Threshold Limit Values” (TLVs).

“What seems to be lost in the current discussion,” says Beaulieu, “is that TLVs are updated as new research is done and new knowledge is gained. Since 2009, the TLV for respirable crystalline silica has been 25 micrograms—half the value in the new standard and the exposure limit that is generally accepted internationally. We’re not going low enough; I’m pushing my clients to get down below 25, because that level seems to be best protective of workers.”

In the Federal Register, OSHA acknowledges that the ACGIH has lowered its TLV for respirable crystalline silica to 25 μg/m3, and the agency has set that PEL as the “action level” of the new standard, which apparently means that workers exposed to between 25 and 50 micrograms must be under “medical surveillance.” But, says OSHA, “Even though OSHA’s risk assessment indicates that a significant risk also exists at the revised action level of 25 μg/m3, the agency is not adopting a PEL below the revised 50 μg/m3 limit, because OSHA must also consider the technological and economic feasibility of the standard in determining exposure limits.”

Feasibility of control

The heart of the respirable crystalline silica standard for construction, 29 CFR 1926.1153, seems to be paragraph (c), “Specified exposure control methods,” along with the accompanying “Table 1: Specified exposure control methods when working with material containing crystalline silica.”

Table 1 lists 18 types of equipment and their tasks, along with the “engineering and work-practice control methods” prescribed for each, plus the “required respiratory protection” for each category, if any. The list ranges from masonry saws, doweling/drilling/coring machines, jackhammers, and grinders to crushers, all sizes of pavement-milling machines, and heavy equipment used to “abrade or fracture silica-containing materials.”

“The standard provides flexible alternatives, especially useful for small employers,” says a recent OSHA Fact Sheet (DSG FS-3681 03/2016). “Employers can either use a control method laid out in Table 1 of the construction standard, or they can measure workers’ exposure to silica and independently decide which dust controls work best to limit exposures to the PEL in their workplaces.”

To make sure we understood what OSHA was saying here, we asked Frank Meilinger, director, office of communication, for clarification. “If an employer fully and properly implements the controls listed on Table 1,” Meilinger said, “the employer is not required to assess the respirable crystalline silica exposure of the worker(s) engaged in that task.”

Industrial Hygiene Resources’ Beaulieu offers a further explanation. “The new standard drives engineering controls and work practices before requiring respirators,” says Beaulieu. “The knee-jerk reaction in the past has been ‘throw the person a respirator.’

“The problem with that approach is that it might not be the appropriate toxic-dust respirator, or the respirator might not fit the worker, or the worker might have interfering facial hair. Also, the worker might not have been trained, and some people are not medically qualified to wear a respirator. The respirator is the second line of defense if other reasonable control methods can’t work—for example, water-spray methods. Employers must remember, too, that respirator use is governed by its own set of OSHA standards—1910.134.”

Although the intent of Table 1 seems straightforward, those opposed to the new standard see potential complications for some contractors.

For example, Table 1 requires that heavy equipment and utility vehicles be equipped with an enclosed cab when used to “abrade or fracture silica-containing materials”...or when used “during demolition activities involving silica-containing materials.” Further, the cab must be pressurized with intake air cleaned through a filter 95 percent efficient in the 0.3-10-micron range, must have heating and cooling capability, and cab seals and gaskets must be in good condition.

“Larger contractors are more likely to have the latest equipment, probably an IH [ industrial hygienist] on staff, and will have less difficulty absorbing the costs associated with implementing the program,” says Una Connolly, vice president, safety and environmental compliance, American Road and Transportation Builders Association (ARTBA). “But the smaller contractor, who’s wearing nine hats and using equipment that’s 10 years old, probably is going to have difficulty even understanding the rule, let alone finding an IH in their area and then funding the required written exposure-control plan.”

In those instances in which air sampling might be required, Connolly questions the value of sampling data for the transportation-construction industry.

“Most often, we work in a different location with different materials every day,” says Connolly. “The results we get back weeks after samples were collected are no longer valid for our current circumstances.”

Connolly also questions whether the specialized laboratories that handle respirable-crystalline-silica air samples will be able to accurately analyze samples at the new PEL. She also sees a further difficulty arising from the relatively small number of “B-readers,” physicians certified by NIOSH, says Connolly, “who can look at an X-ray and definitively determine that silica exposure is involved.” In some instances under the new OSHA standards, a B-reader is required to interpret X-rays of at-risk workers.

(NIOSH instituted the B-reader program in 1974, after becoming concerned about the variability of interpretations among those reading X-rays from coal miners suspected to be suffering from Black Lung disease. Today, B-readers are specialists at identifying pneumoconioses, occupational lung diseases caused by inhaling dust. A  NIOSH website lists 197 B-readers in the United States.)

Industrial Hygiene Resources’ Beaulieu, however, does not see the supply of certified industrial hygienists, qualified laboratories, or B-readers as a significant obstacle to implementing the new OSHA standard.

“There are more than 6,000 certified industrial hygienists in the U.S.,” says Beaulieu, “and perhaps 150 labs—accredited by the American Industrial Hygiene Association—that can analyze silica down to the lower PEL with absolutely no problem. That’s not to say that only a certified IH can collect dust samples from a worker’s breathing zone, but sampling does require experience in order to assess the worker’s various exposures in a typical work day, and then to develop an average exposure that is realistic for that person.”

Sampling devices and techniques must meet the criteria established by the ISO (International Organization for Standardization) 7708:1995 code.

Other provisions

  • Assessing exposure: If a task is not listed in Table 1, then the employer must abide by paragraph (d) in the Final Rule for construction, “Alternative exposure control methods,” which includes the requirement to assess “the exposure of each employee who is, or may reasonably be expected to be exposed to respirable crystalline silica at or above the action level,” which, as noted, is 25 micrograms. Air samples must be analyzed by a laboratory that follows OSHA-prescribed procedures.
  • Respiratory protection: According to paragraph (e), respiratory protection is required “where specified by Table 1, or for tasks not listed in Table 1, or where the employer does not fully and properly implement the engineering controls, work practices, and respiratory protection.” The assumption here seems, at least, to be predicated on PELs established by assessing exposures.
  • Housekeeping: If dry sweeping or brushing could contribute to silica exposure, these activities, says paragraph (f), are not allowed, unless wet sweeping or HEPA-filtered vacuuming is not feasible. Cleaning clothing or surfaces with compressed air is also not allowed, unless the compressed air used is properly ventilated.
  • Written exposure-control plan: Among the most demanding requirements are those of paragraph (g), which require employers to “establish and implement” a written plan that describes the tasks involving silica exposure and the engineering controls, work practices, respiratory protection, and housekeeping practices to be used in limiting exposure. Plus, the employer must designate a “competent person” to oversee the plan’s implementation.
  • Medical surveillance: The provisions outlined in paragraph (h) for “medical surveillance” are lengthy and detailed, requiring careful reading by employers. In general, “the employer shall make medical surveillance available at no cost to the employee, and at a reasonable time and place, for each employee who will be required under this section to use a respirator for 30 or more days per year.”
  • Hazard communication: This section, paragraph (i), essentially obligates employers to make employees aware of silica health hazards, identify those tasks in which exposure is a risk, and to tell employees what measures have been taken to reduce the risk to silica exposure.
  • Recordkeeping: Briefly, paragraph (j) requires that the employer shall make and maintain an accurate record of 1) all exposure measurements taken to assess employee exposure to respirable crystalline silica (with much detail),  2) “objective data” including testing protocol and results, and 3) medical surveillance records of those employees who are covered by the surveillance provisions.

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