OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

March 24, 1993

Marc B. Evans, C.I.H., C.S.P.
Blasland & Bouck Engineers, P.C.
6723 Towpath Road Box 66
Syracuse, New York 13214-0066

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 us at (202) 219-8036.


Roger A. Clark, Director
Directorate of Compliance Programs

August 28, 1992

Ms. Patricia Clark, Director
Directorate of Compliance Programs
U.S. Department of Labor
Occupational Safety and Health Administration
Washington, D.C. 20210

Re: Fugitive Dust Suppression/ Particulate Monitoring Program at Inactive Hazardous Waste Sites

Dear Ms. Clark:

Attached for your review and comment is a document provided by the New York Department of Environmental Conservation (NYDEC) to the DECs Regional Hazardous Waste Remediation Engineers, etc., regarding dust suppression and monitoring programs at inactive hazardous waste sites. Please note that the DECs October 27, 1989 correspondence reference a July 1, 1987 EPA ambient air quality standard for particulate.

Over the last years we have prepared several health & safety plans (HASP) for investigative type projects in the State of New York. For projects involving potential generation of contaminated dust, and, consequently, potential occupational exposure to such dust, our HASPs contain provisions for dust monitoring, suppression, and the use of personal protective equipment (PPE). In all cases our HASPs reference 1910.120 as the basis for HASP development, and also 1910.1000 (or related substance specific standard) for the Permissible Exposure Limit (PEL). Our HASP will also contain a dust "action level" which is calculated utilizing the known soil concentration of the contaminant of concern and a safety factor. For example, a soil containing 10,000 mg/kg. of lead will have a calculated action level of 1.0 mg/m(3), calculated as follows:

Action Level (mg/m(3))   =                (10(6) mg/kg)  x  (PEL mg/m(3))
                            (Soil Concentration mg/kg)  x  (Safety Factor)

In calculating the 1.0 mg/m(3) action level, a safety factor of 4 was utilized.

Although the OSHA PEL for lead is 0.05 mg/m(3) (which our calculated action level is based on), our interpretation of the calculated action level is that it would take at least 1.0 mg/m(3) of total dust in the air to achieve a dust level which could potentially contain the lead PEL of 0.05 mg/m(3). By calculation it would take approximately 0.750 mg/m(3) total dust in air (using the same safety factor of 4) to achieve the OSHA action level of 0.03 mg/m(3) lead in the dust cloud. In this case, our HASP would require we start work in Level C, monitor the ambient air with a aerosol monitor, and if dust levels did not exceed the calculated 1.0 mg/m(3) action level, we would downgrade to Level D. Our HASP would also contain a number of dust suppression measures for controlling dispersion should the 1.0 mg/m(3) action level be exceeded. Our HASP would also include personal monitoring for lead as well as pre-site entry and post-site activity biological monitoring in the form of blood lead and zinc protoporphyrin.

The issue I have concerns the interpretation of 1910.120, specifically in regard to the use of PELs as required by 1910.120; and our response when another agency such as the EPA develops an additional guideline which dictates using their guideline in our HASP. As per the attached document, the EPA has developed a PM(10) for fugitive dust whether contaminated or not of 0.15 mg/m(3). The same os considered "requisite to protect public health," and was actually developed as an 24-hour time weighted average. The guidance section of the documents suggests that the 0.15 mg/m(3) be considered a 15-minute STEL.

We believe that the PM(10) may have application for fenceline monitoring, providing a guideline for perimeter monitoring and subsequent dust control; however, we do not believe such a guideline should be developed and enforced by an agency other than OSHA as a health and safety action level for inclusion in a HASP. HAZWOPER is very specific in that the regulation is contained in 29 CFR and not 40 CFR (other than Part 311 for employees of State and local government in States without approved State plans). In addition, HAZWOPER addresses occupational safety and health which requires a HASP and the use of OSHA PELs and not air quality standards initially developed by other agencies for purposes not related to occupational exposure.

Although OSHA has been in existence for over 20-years, the effective date of HAZWOPER is just slightly over 2-years old. Prior to OSHAs entry into regulating safety and health of hazardous waste workers, many proactive companies conducting waste site activities utilized EPA standard operating procedures (SOPs) as guidance for worker safety and health. In many cases, and despite their absence in HAZWOPER, this is why we continue to see (and struggle with) the organic vapor action levels contained in EPA field operation manuals and used for upgrading levels of protection. Due to that prior guidance, many companies still do not understand the need to conduct personal air sampling upon potentially exposed sit employees for comparison to corresponding PELs. Consequently, total organic vapor levels recorded with direct reading instrumentation are continuously and incorrectly used for comparison to established OSHA PELs. Many of these companies continue to take their lead from EPA despite OSHAs role in regulating hazardous waste site worker safety and health in 1910.120.

Consequently, the use of the EPA PM(10) dust suppression and monitoring action level as an occupational health and safety exposure limit is an additional example of the need for clarification in the roles and responsibilities among the agencies. We believe that without additional clarification, such non-occupational guidance numbers will continue to be pulled off the shelf and incorrectly applied to worker safety and health. Despite the EPA PM(10) being more restrictive than our calculated action level in the above example, the use of the this EPA number is being inappropriately utilized. It should be noted that while the above example used lead (a well regulated, toxic metal having a low PEL), we have worked at other sites having materials considered as Particulate Not Otherwise Classified (PNOC) which OSHA currently regulates at 15 mg/m(3) in which the DEC has instructed us to again use the PM(10) as a particulate action level for dust suppression and Level C protection. The mandated use of inappropriate guidance numbers by agencies such as DEC will continue to create confusion and inconsistency in protecting the safety and health of waste sit workers.

What role and authority does an agency such as DEC have with respect to mandating exposure guidelines in HASPs developed in accordance with OSHA's 1910.120? In complying with 19.120, how should an environmental consulting firm balance the need to develop a HASP that complies with OSHA requirements (that protect the safety and health of field workers), with contradictory mandates from environmental agencies having project oversight, but not safety and health expertise?

I would appreciate your review of these issue. While the same may border on the "inter-agency gray area," and not be easily answered by reference to a specific section in HAZWOPER, they are nevertheless issues which need to be clarified. I believe that such issue can also impose additional liability on environmental firms without justification by imposing unnecessary exposure control levels, creating the need for unnecessary levels of protection which in turn create street on client relationships and also convey unnecessary messages to neighboring communities.

Thank you for you time and input.

Very truly yours,


M.B. Evans CIH/CSP
Manager, Health & Safety