Dust exposure monitoring in hazardous waste site plans

March 24, 1993

Marc B. Evans, C.I.H., C.S.P.
Blasland & Bouck Engineers, P.C.
[Recipient address omitted]
Dear Mr. Evans:

This is in response to your inquiry of August 28, 1992, concerning the Occupational Safety and Health Administration's (OSHA) Hazardous Waste Operations and Emergency Response (HAZWOPER) regulation, 29 CFR 1910.120. We apologize for the delay in this response. OSHA has reviewed your approach to preparing health and safety plans (HASP) for hazardous waste sites, and has the following comments.

Your reference to EPA "developing additional guidelines which dictate using their guidelines in our HASP" is unclear. OSHA has general legal authority to regulate worker safety and health in the areas you are discussing. While there are exceptions in which EPA has authority to regulate safety and health, they do not appear to be relevant to your case.

However, if an entity such as your firm enters into a contract agreement with an agency such as the EPA or the New York State Department of Environmental Conservation (DEC) to carry out more stringent safety and health procedures than those required by OSHA but which meet OSHA's requirements, you would be required by your contract to follow those stricter measures.

The New York State DEC would be the proper source for definitive interpretations of their requirements. Our understanding from your letter is that DEC is requiring that airborne concentrations of particulate matter of 10 micrometers (um) or less in size be limited to one hundred fifty micrograms per cubic meter (150 ug/m(3)), as measured over a 15-minute period in accordance with the U.S. Environmental Protection Agency's (EPA) perimeter management (PM(10)) standard. If dust levels exceed this value, the employer must initiate additional dust suppression procedures and corrective actions, including the use of additional personal protective equipment. If dust suppression techniques fail to achieve the 15-minute, 150 ug/m(3) limit, work must be suspended until "appropriate corrective measures are approved to remedy the situation."

EPA's preamble to the 1987 final ambient air quality standard makes clear that the PM(10) limit, which is expressed as a 24-hour average limit on fugitive dust levels, is designed to minimize the risk of mortality and respiratory disease among sensitive individuals who are exposed to excessive dust levels for prolonged periods of time:

"The intent of the margin of safety requirement (used by EPA to develop the standard) was to direct the Administrator to set air quality standards at pollution levels below those at which adverse health effects have been found or might be expected to occur in sensitive groups....The portions of population at greatest risk of premature mortality associated with particulate matter exposures...include the elderly and persons with pre-existing respiratory or cardiac disease." [52 FR 24641, 24643]

EPA also based their standard, in part, on evidence that small children and persons with chronic bronchitis may be adversely affected by prolonged exposure to dust levels exceeding the 150 ug/m(3) PM(10) standard.

In your letter, you express your opinion to OSHA that, while the PM(10) standard may have application for fenceline monitoring, it should not be enforced as a worker safety and health action level. OSHA would only enforce its own standards. The use of the PM(10) standard expressed as a 15-minute short-term action level for nuisance dusts would provide a conservative protective measure for workers at hazardous waste sites.

There is some concern that application of this action level for nuisance dusts may result in the use of personal protective equipment in areas where there is little or no possibility of exceeding a permissible exposure limit for workers. OSHA would only require that personal protective equipment be selected based on personal air monitoring designed to determine whether employee exposures to hazardous substances are likely to exceed OSHA Permissible Exposure Limits (PELs) or other published exposure levels. As stated in 29 CFR 1910.120(g)(2), PPE selection for substances for which there is no OSHA PEL shall be based on published exposure levels in the National Institute for Occupational Safety and Health (NIOSH) "Recommendations for Occupational Health Standards" or, if none is specified, in the American Conference of Governmental Industrial Hygienists (ACGIH) "Threshold Limit Values and Biological Exposure Indices;" for substances for which there is no published exposure level, other published exposure information may be used.

The site safety and health officer should take care to choose PPE so that employees are neither inadequately protected from exposures to hazardous substances, or conversely, must wear an excessive amount of protective equipment, thus needlessly exposing employees to hazards caused by heat stress, excessive fatigue, and restricted vision.

Accordingly, the approach taken by Blasland and Bouck appears reasonable, provided that safety and health plans also call for personal monitoring of exposure to hazardous substances at intervals sufficient to characterize employee exposures. OSHA's final determination of compliance would be based on a thorough evaluation of the safety and health plan with respect to its specific site application.

The employer must start by performing a thorough site characterization and analysis to determine the nature and extent of the actual hazards on a site. The information which must be gathered is set forth in 29 CFR 1910.120 paragraph (c). As a result of this process, the employer is able to designate uncontaminated areas, which are low hazard areas where no special protective equipment is necessary, and contaminated, or "hot" zones, where use of personal protective equipment (PPE) will be required. Since site conditions and activities or weather conditions may change, the employer must have an on-going site characterization program, in which zone boundaries are modified accordingly.

Monitoring, as required in paragraph (h) of the standard, is an essential element of the ongoing site characterization process. Monitoring during initial site entry shall identify substances present in excess of the PEL (or other published exposure levels) as well as any other dangerous conditions. Once clean-up operations have begun, personal monitoring is required for all employees likely to be exposed above the PEL (or other published exposure levels). Representative sampling techniques may be used. Since selection of PPE is to be based on the results of the monitoring, methodologies which provide adequate information on actual exposure levels for individual contaminants must be used.

In the example you describe, you use the OSHA PEL for lead as your starting point and work backwards to calculate an acceptable dust exposure level, or "action level." The validity of this approach assumes that the lead content of the dust remains constant. Therefore this approach is acceptable only for the preliminary evaluation prior to site entry by employees, and must be followed by a detailed evaluation, including appropriate personal monitoring with direct sampling for lead.

Paragraph (a)(2)(i) of the HAZWOPER standard states that where 1910.120 overlaps with another OSHA standard, the provision which is more protective of employee safety and health shall apply. 29 CFR 1910.1025, Occupational Exposure to Lead, paragraph (d)(6) requires that personal monitoring be conducted quarterly for employees exposed above the PEL, and once every six months for employees exposed above the action level. Additional monitoring is required whenever there has been a change which may result in new or additional exposures. 29 CFR 1910.120(h)(3) requires that monitoring be conducted whenever it is suspected that levels may have risen over the PEL since prior monitoring; for example, monitoring is indicated whenever work begins on a different portion of the site or a different type of operation is initiated. You must determine which of these requirements is more protective for the site in question.

Further, dust is, itself, a potential health hazard. (As you are aware, OSHA has established a PEL for dust, referred to as Particulates Not Otherwise Regulated (PNOR).) The PELs for PNOR are as follows: 15 mg/m(3) for total dust and 5 mg/m(3) for the respirable fraction. You must perform a separate evaluation for dust exposure using the PEL for PNOR.

You seem to imply that OSHA has regulated safety and health at hazardous waste sites for only 2 years. This is not the case. OSHA has exercised authority in these workplaces prior to the promulgation of HAZWOPER through the use our general industry and construction industry safety and health regulations, including standards specifying permissible exposure limits.

We hope this information is helpful. If you have any further questions please contact [the Office of Health Enforcement at (202) 693-2190].

Sincerely,
Roger A. Clark, Director
Directorate of Compliance Programs

[Requester letter reproduced on OSHA page; omitted here.]

[Corrected 12/6/2024]