concurring specially:
Because the “concentrations” of asbestos fibers found in the GAF plants in this case were not insignificant, and because the record shows that petitioner had adequate notice that the Commission would construe its regulation to require physical examinations at these “concentrations,” I reluctantly concur in the result reached by the panel. I believe, however, that the Secretary of Labor should clarify the regulation governing medical examinations so as to give other persons subject to the regulation reasonable notice of some measurable quantity of airborne asbestos the Commission intends to trigger the medical examination requirement. Merely to state that all employers must provide medical examinations whenever their employees are exposed to “concentrations” of asbestos fibers does not provide an ascertainable standard for those who wish to comply with the law.
The regulation provides that employers must provide medical examinations to each employee “in an occupation exposed to airborne concentrations of asbestos fibers,” 29 C.F.R. § 1910.1001(j)(2) and (3) (1976) (emphasis added). No person can discern from this language what degree of “concentration[ ]” must exist before medical examinations are required. Other asbestos exposure regulations which do set ascertainable exposure limits provide:
(b) Permissible exposure to airborne concentrations of asbestos fibers. (1) Standard effective July 7, 1972. The 8-hour time-weighted average airborne concentrations of asbestos fibers to which any employee may be exposed shall not exceed five fibers, longer than 5 micrometers, per cubic centimeter of air, as determined by the method prescribed in paragraph (e) of this section.
(2) Standard effective July 1, 1976. The 8-hour time-weighted average airborne concentrations of asbestos fibers to which any employee may be exposed shall not exceed two fibers, longer than 5 micrometers, per cubic centimeter of air, as determined by the method prescribed in paragraph (e) of this section.
29 C.F.R. § 1910.1001(b)(1) and (2) (1976). The prescribed standards in these regulations were: “five fibers, longer than 5 micrometers, per cubic centimeter of air,” and after July 7, 1976, “two fibers.” These standards inform the nation’s employers precisely what degree of exposure is permitted and what exposure is excessive, but the regulation requiring medical examina*27tions is almost completely deficient in this respect.
What number of fibers, of what length, per what volume of air will constitute a “concentration” is nowhere stated or even hinted at — and like the regulation, the court’s opinion leaves the matter completely to conjecture. This is particularly unsettling to law abiding citizens when the agency is dealing with tremendously minute quantities of infinitesimally small particles. It makes compulsory law enforcement difficult and it lessens the likelihood of voluntary compliance with the law, a result devoutly to be wished. The first requirement for uniform and voluntary compliance with the law is a clear understandable statement of what conduct is required and this regulation falls woefully short of that minimal requirement.
Regulations that have the great importance that this regulation has to human life should be written in more precise terms — so people of ordinary understanding can determine what course of conduct is being required of them. What one person might consider to constitute a “concentration” will differ greatly from the interpretation that another would give to that term; and what one person today might regard not to constitute a concentration” might be considered tomorrow, on the basis of hindsight as medical knowledge increases, to come within that term.1
The statute requires the Secretary to “set [a] standard”:
(5) The Secretary, in promulgating standards dealing with toxic materials or harmful physical agents under this subsection, shall set the standard which most adequately assures, to the extent feasible, on the basis of the best available evidence, that no employee will suffer material impairment of health or functional capacity even if such employee has regular exposure to the hazard dealt with by such standard for the period of his working life. Development of standards under this subsection shall be based upon research, demonstrations, experiments, and such other information as may be appropriate. In addition to the attainment of the highest degree of health and safety protection for the employee, other considerations shall be the latest available scientific data in the field, the feasibility of the standards, and experience gained under this and other health and safety laws. Whenever practicable, the standard promulgated shall be expressed in terms of objective criteria and of the performance desired.
29 U.S.C. § 655(b)(5) (1970) (emphasis added). The agency has promulgated standards that state “objective criteria and . the performance desired” for employee exposure on the job but it has not done as much for medical examinations. It is practical to state “objective criteria” for medical examinations and I believe the agency should do so. Merely requiring medical examinations whenever there is some indefinite, ambiguous, nonspecific degree of “concentration” does not meet the requirement for a feasible standard with objective criteria that Congress imposed on the agency.2 This is a serious dereliction because, if in the future medical knowledge progresses to the point where more minute quantities of asbestos fibers are found to be harmful than are presently so considered, *28then employers in the distant future may be held liable to the extent of millions of dollars in tort suits based on their alleged failure to provide the required medical examinations that would have prevented, or discovered at a preventable stage, what eventually turned out to be a fatal disease.
In such lawsuits for damages the present ambiguous regulation would have the status of a statute and failure to conform to some more strict post hoe interpretation of its provisions might constitute negligence per se. As Professor Prosser states the law:
Once the statute is determined to be applicable — which is to say, once it is interpreted as designed to protect the class of persons in which the plaintiff is included, against the risk of the type of harm which has in fact occurred as a result of its violation — the great majority of the courts hold that an unexcused violation is conclusive on the issue of negligence, and that the court must so direct the jury. The standard of conduct is taken over by the court from that fixed by the legislature, and “jurors have no dispensing power by which to relax it,” except in so far as the court may recognize the possibility of a valid excuse for disobedience of the law. This usually is expressed by saying that the unexcused violation is negligence “per se,” or in itself.
W. Prosser, Torts 200 (4th ed. 1971). When it can be avoided, a statute or regulation should not by its mere indefiniteness expose employers to such great hazards.3 The agency should state in clear, understandable objective terms specifically what degree of “concentration” triggers the requirement for medical examinations — be it one fiber per cubic foot of air or one fiber per 100 cubic feet of air, or some other unambiguous, quantitative standard. Imposing a non-specific ambiguous standard is completely unsatisfactory. “Concentration” is a noun, the meaning of which varies greatly depending upon the context in which it is used. Concentration can be high, low, medium, dangerous, hazardous, insignificant, “negligible,” etc. — standing alone its meaning is highly indefinite. It would not be difficult to state a standard with precision.
A recent case before the Connecticut Occupational Safety and Health Review Commission, Tuttle & Bailey Div. of Allied Thermal Corp., No. 76-315 (Conn. OSAHRC, Dec. 3,1976), involved a state medical examination requirement in language practically identical to that present here, and a similar factual situation. In that case the State Commission decided that the word “concentration” in the standard must have been intended to have some meaning, because if no threshold of exposure were intended, the word “concentration” could be omitted without changing the meaning of the section. It would then address itself to “airborne asbestos fibers.” The State Commission reasoned:
If this Commission were to adopt the interpretation as proposed by the Labor Commissioner, the effect would be to establish a requirement “. . that whenever employees are exposed to any trace of asbestos — no matter how temporary or insignificant — their employer must furnish (and employees must undergo) — annual physical examination and tests as prescribed in [the regulation].”
This Review Commission cannot conclude that the intent of this regulation is to require such examination for the occasional “messenger” or “visitor” entering *29the exposure area, nor the employee far removed from the source whose exposure is in fact minimis concentration of airborne asbestos fibers. The Review Commission concludes that the word “concentration” has a meaning as used within the regulation.
Id. at 5-6.
The Commission also noted:
One can conceive of very different circumstances wherein employees would be exposed to airborne concentration of asbestos fiber, to varying degrees and for varying periods of time. For an employer to try to determine whether or not medical examination[s] as required by [the regulation] should be provided or not provided under a “reasonable man” theory would be most difficult. To attempt to apply a “reasonable person” standard in recognizing a hazard of microscopic concentration of asbestos fiber in the air, is not in itself reasonable. Reasonable laymen cannot conceive a rule of conduct in an area where reasonable experts cannot agree.
Id. at 6-7 (emphasis added). The Commission therefore concluded that it was
unable to determine what [the] threshold [of concentration] is or should be, nor does this Commission accept that a reasonable employer could so determine.
Id. at 7. Finally, it held that until the regulation was redrafted to state its intended meaning in clear understandable terms, the Commission would assume that the 5 fiber standard applied as well to the physical examination provision. The State Commission appeared to recognize that this interpretation was not directly supported by the language of the regulation, but based its holding on the necessity for some understandable meaning. If the instant case were disposed of on a similar rationale, the two-fiber limit presently in force in 29 C.F.R. § 1910.1001(b)(2) would also govern the medical examination requirement.
Recently, the Federal Commissioners attempted to distinguish their decision presently under review on the ground that “GAF did not involve the situation . where the concentration of the air contaminant is negligible compared to the limit established by the standard.” Western Electric, Inc., No. 8902, at 7 (OSHRC, Jan. 24, 1977) (emphasis added). What “standard” the Commission had in contemplation was not disclosed, nor was there any reference to what “limit” they were applying. But the reference of the Commission to a “negligible” amount indicates some quantitative standard was intended. It would be helpful if the Secretary would state what that “standard” is. That is not a difficult task if he has one in mind. If he does not have one in mind he should have. Maybe the Secretary does not have substantial evidence to prove that the “standard” of “concentration” the Commission applying constitutes a “hazard,” and that may be the reason the Secretary chose to leave it in an ambiguous state. As it is now, both the Secretary and the Commission are home free leaving the public in the dark as to what degree of “concentration” is more than “negligible” according to some unstated “standard” of “concentration.”
Such imprecision should not be countenanced in such an important matter. Nothing would be lost by requiring the agency to state a specific objective standard — and everybody would benefit. It could be done quickly and there would not be any delay in enforcement.
It is also my opinion that permitting the entire state of California to have a specific standard that is different, and more liberal, from that applied to appellants in this case, and throughout the rest of the nation, is highly questionable. The mere availability of more investigators in California is not a permissible basis for allowing employees to be exposed to more asbestos fibers before a medical examination is required. The number of investigators is not germane to the hazard produced by the added contamination of more asbestos fibers.
The evidentiary record in this case does not in my opinion present a case of sufficient strength to justify setting aside the regulation, but there is every indication that a proper case can be made to achieve *30such result. I accordingly strongly suggest that the Secretary should amend the regulation to establish the definite workable and understandable “standard” with “objective criteria” that the statute requires.
. A current textbook tells us:
The toxic concentration of asbestos in the air has not been established. However, the threshold limit values for its concentration in air with eight hours’ exposure daily has been accepted as 5 million particles per cubic foot of air, based on impinger samples counted by the light-field technique.
4 R. Gray, Attorney’s Textbook of Medicine 132-71 (3d ed. 1977). The evidence in this record does not indicate how this sampling method might vary from the Commission’s two fibers per cubic centimeter in 29 C.F.R. § 1910.-1001(b)(2) (1976); however, this standard permits less than ‘Aoth the number of fibers Gray finds acceptable. The Commission’s interpretation of § 1910.1001(j)(2) and (3) establishes an even lower indeterminate figure for the medical examination requirement.
. It is conceded that the regulation requiring medical examinations is imposed under the Secretary’s authority to “promulgate standards dealing with . . . harmful physical agents . . . .” 29 U.S.C. § 655(b)(5), supra.
. The potential problem of tort liability is particularly serious because of a high background level of asbestos fibers in many geographic areas. Some medical studies are currently reported to have “found [that] people who have never been exposed to asbestos in the workplace show a scarring of tissues around their lungs that looks exactly like scarring found in asbestos workers.” Area Dust Found High in Asbestos Fibers, Washington Post, Dec. 19, 1975, at A8, col. 1. The high incidence of asbestos fibers in the air of cities may be traceable to the use of asbestos brake linings in automobiles, and to the use of rock aggregates containing asbestos fibers. The extent of air pollution by asbestos from these sources has not yet been accurately assessed. See EPA Cites Asbestos Hazard: Montgomery Parks Closure Urged, Washington Post, June 8, 1977, at Al, col. 4 & A10, col. 1.