NIOSH action level

The Decision Rules. The NIOSH action level is a statistical decision threshold designed to help employers attain a high degree of confidence that no more than a small fraction of any employee s daily exposures exceed the standard. After developing the action level, NIOSH provided a set of decision rules to be used by employers who want to determine if their workplaces meet this objective an exposure estimate smaller than the action level indicates that the employer has probably achieved the objective an estimate larger than the standard probably indicates a serious... 

The comparison is conducted by identifying those occupational environments which will pass or fail each set of decision criteria. This paper deals only with occupational stresses which pose a chronic health hazard acute health hazards require different treatment. The most surprising conclusion is that there are some commonly encountered work environments which are very likely to pass the NIOSH Action Level Test even though there is better than a 50% chance that an OSHA compliance officer collecting six samples during one visit would be able to identify a citable violation of an 8-hour PEL. 

The model of occupational exposures which forms the basis for the proposed NIOSH Action Level is introduced in this first section the NIOSH decision criteria are generalized in the second section and the decision probabilities are compared in the last section of this paper. A conscious effort has been made to present important results graphically, but the appendix contains equations so that an interested, mathematically-inclined reader can check or extend the results. 

These decision rules can be generalized to permit easy comparison between OSHA decisions and NIOSH decisions by defining several new terms. Let UAL represent the upper action level, which is to be used in place of the standard. Let OK represent an acceptable workplace and let NOT OK represent an unacceptable workplace. Let P indicate the probability that the indicated decision is made. Thus, P( ) represents the probability that a decision cannot be made with sufficiently high confidence on the basis of one breathing zone sample. Under these definitions, the decision rules become ... 

Decisions Made by the NIOSH Action Level Criteria. Figure 3 shows the decision contours for the NIOSH Action Level Decision Criteria, and Table I summarizes the decision probabilities for each of the nine sample workplaces. Recall from Equation A-19 that the AL is computed from GSD to provide 95% confidence that no more than 5% of the daily exposures exceed the standard if one randomly collected sample is less than the AL. In terms of the variables used in this paper, (e > 0.05 with p > 0.05 if X > AL). 

In Table I, the NIOSH decision criteria is shown to have poor efficiency by the three dirty workplaces for which e = 0.6. In these cases, a worker would be exposed above the standard three days out of five, and his long-term average exposure would be greater than the 8-hour PEL. Very few people would disagree with the decision to call these workplaces NOT OK. Nevertheless, these workplaces will be declared NOT OK bv the NIOSH Action Level decision criteria only about 60% of the time. This inefficiency is further illustrated by the fact that only one of the three average workplaces with e = 0.2 has P( ) < 0.75. That one is (0.2, 1.13) and it also illustrates the conservativeness of the NIOSH criteria since on those infrequent occasions when a decision is made, the odds are 21 to 1 to decide NOT OK. However, Table I most clearly illustrates the conservativeness of the NIOSH criteria by the fact that P(0K) < 0.1 for the three clean workplaces where e = 0.024. 

Decisions Made with the Legal Action Level Criteria. Proper application of the NIOSH Action Level (Equation A-19) requires... 

Figure 3. Decision contours resulting from the NIOSH Action Level Criteria AL = f(GSD), and UAL = 1. Each marks the location of one of the charts from Figure 1. Note that the NO DECISION region includes nearly the whole area between the GSD axis and the NOT OK region.

Leidel, N.A., K.A. Busch, and W.E. Crouse. "Exposure Measurement Action Level and Occupational Environmental Variability," Department of Health, Education, and Welfare, National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati, NIOSH Technical Information, HEW Pub. No. (NIOSH) 76-131, Cincinnati, Ohio 45226, April 1975. 

The Action Level. By combining the last equation in Ref 2 with tquation A-l4, one can derive an explicit equation for the NIOSH Action Level. 

Figure 3.2 NIOSH-recommended employee exposure determination and measurement strategy. AL — action level PEL = permissible exposure limit. OSH A Laboratory Standard 29 CFR 1910.1450 requires employee notification of any monitoring results...

The current OSHA permissible exposure limit (PEL) for all workplaces covered by OSHA is 0.75 ppm for an 8-hour TWA, and the short-term exposure limit (STEL) is 2 ppm over a 15-minute period. The "action level" is 0.5 ppm measured over 8 hours (OSHA 1996). NIOSH has recommended a 0.1 ppm ceiling exposure concentration over a 15-minute period in the workplace (NIOSH 1992). 

EXPOSURE GUIDELINES ACGIH TLV (insoluble compounds) 0.2 mg/m OSHA PEL TWA (soluble compounds) 0.05 mg/m OSHA PEL TWA (insoluble compounds) 0.2 mg/m NIOSH REL (insoluble compounds) 0.15 mg/m NIOSH REL (soluble compounds) 0.05 mg/m NCRP (indoor air guideline) 8 pCi/L EPA (indoor air action level and guideline for schools) 4 pCi/L. 

Exposure Measurement Action Level and Occupational Environmental Variability," HEW Publication No. (NIOSH) 76-131, December, 1975. 

At the time, the OSHA proposal was for an action level of 50 pg/m, which NIOSH endorsed in its criteria document as a future goal to provide greater assurances of safety (NIOSH 1978, p. XII-19). That air level would keep BLLs at about 40 pg/dL or lower in virtually all workers, protecting against subclinical effects of lead. NIOSH also endorsed a vigorous medical surveillance program for workers exposed above the action level but below the proposed maximum air lead concentration of 100 pg/m. NIOSH estimated that even at the proposed air standard of 100 pg/m less than half of the workers will have blood lead levels above 40 [pg/dL] (NIOSH 1978, p. XII-19). 

Terminology used by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) to state the level of toxicant that requires medical surveillance and training to further protect employees. It is usually one-half the level of the permissible exposure limit. Action levels exist for only a few air contaminants, such as lead, cadmium, and benzene. Activated Charcoal... 

The Occupational Safety and Health Administration (OSHA) standard for exposure to asbestos defines a fiber as one at least 5 p,m long with a length/diameter ratio of at least 3.0. The TLV-TWA is 0.1 fibers/cc of air the excursion limit for a 30-min sampling period is 1.0. The standard, published in 29 CFR 1910.1001 specifies sampling methods and fiequencies as well as the analytical procedure (NIOSH Method 7400). Some countries allow higher concentrations of fiber. In Brazil, Canada, and Mexico, for example, the TLV is 2 fibers/ml. In the European Union, the TLV is 0.6 fibers/ml (0.25 in Germany), with an action level of 0.2. 

Several government regulatory agencies have taken action to protect people from excess exposure to hydrazines. EPA considers hydrazine and 1,1-dimethylhydrazine to be hazardous air pollutants. The Occupational Safety and Health Administration (OSHA) limits the amount of hydrazine and 1,1-dimethylhydrazine to 0.1 and 0.5 ppm, respectively, in workplace air for an 8-hour workday and notes the potential for skin absorption in unprotected individuals. The National Institute of Occupational Safety and Health (NIOSH) recommends that the levels of hydrazine and 1,1-dimethylhydrazine in workplace air not exceed 0.03 and 0.06 ppm. 

The vapors of VM P solvent are irritant to the eyes and upper respiratory tract. Such irritant action in humans may be manifested at an exposure level of 1000 ppm for 15 minutes. It is narcotic at high concentrations. The symptoms noted in rats of acute exposure were loss of coordination as well as convulsions. The inhalation LC50 value for 4-hour exposure in rats is 3400 ppm (NIOSH 1986). 

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