Workplace safety and health programs, practices, and conditions in auto collision repair businesses.

This article describes the results of a pre-intervention safety assessment conducted in 49 auto collision repair businesses and owners' commitments to specific improvements. A 92-item standardized audit tool employed interviews, record reviews, and observations to assess safety and health programs, training, and workplace conditions. Owners were asked to improve at least one-third of incorrect, deficient, or missing (not in compliance with regulations or not meeting best practice) items, of which a majority were critical or highly important for ensuring workplace safety. Two-thirds of all items were present, with the highest fraction related to electrical safety, machine safety, and lockout/tagout. One-half of shops did not have written safety programs and had not conducted recent training. Many had deficiencies in respiratory protection programs and practices. Thirteen businesses with a current or past relationship with a safety consultant had a significantly higher fraction of correct items, in particular related to safety programs, up-to-date training, paint booth and mixing room conditions, electrical safety, and respiratory protection. Owners selected an average of 58% of recommended improvements; they were most likely to select items related to employee Right-to-Know training, emergency exits, fire extinguishers, and respiratory protection. They were least likely to say they would improve written safety programs, stop routine spraying outside the booth, or provide adequate fire protection for spray areas outside the booth. These baseline results suggest that it may be possible to bring about workplace improvements using targeted assistance from occupational health and safety professionals.

Employers' expectations of knowledge and skills of master's-trained industrial hygienists.

Certified industrial hygienists with recent hiring experience were surveyed about their expectations of competencies when hiring entry-level master's-trained industrial hygienists. Results were used to affirm educational objectives and program outcomes required by new program accreditation criteria. We received 129 completed surveys from 179 eligible participants agreeing to participate. Most of the respondents were employed in very large companies (>500 employees) and were evenly distributed in manufacturing, services, and public administration. More than 70% of respondents identified essential knowledge and skills in 11 topic areas that fall entirely within the categories of recognition, evaluation, and control. Environmental and management topics were identified as essential by less than 25% of the respondents. Nineteen competencies identified as essential by 60% of the respondents were entirely in the categories of recognition, evaluation, control, and communication. Less than 50% of the respondents thought competencies in the management area were useful but not essential. Air sampling pumps, sound level meters, noise dosimeters, and direct-reading instruments were the mostfrequently listed equipment with which industrial hygienists should be familiar. These survey results represent the first systematic input from employers on their expectations for competencies of master's-trained industrial hygienists.

Designing intervention effectiveness studies for occupational health and safety: The Minnesota Wood Dust Study.

BACKGROUND: A planning model was used to guide the design of a randomized controlled study of the effectiveness of tailored interventions in lowering dust exposures in small woodworking shops. METHODS: Guided by Green's PRECEDE-PROCEED model, we used a planning committee, focus groups and a pilot study to gain information on small woodworking shops, causes of and controls for high dust levels, and barriers and incentives surrounding availability and use of dust controls. RESULTS: The planning committee identified key characteristics of small woodworking shop owners. Focus groups with owners and employees served to further elucidate why dust control was considered unimportant. The pilot study gave measures of dust exposures, tasks, and use of controls. Interventions focused on providing owners with technical and economic assistance to lower dust levels and an educational program for employees discussing health effects and effective methods of dust control. CONCLUSIONS: The PRECEDE-PROCEED model proved a useful framework for designing an intervention in the occupational setting.

Review of "Implications of Hormesis for Industrial Hygiene".

Hormesis is an appealing concept when considered from the evolutionary viewpoint. It may provide a new approach to deriving the "no observed adverse effect level" for occupational exposures to chemicals. An over-reliance on mathematical modeling without a clear understanding of exposures and health outcomes stymies current scientific decision-making. Care must be taken, however, as not all endpoints will exhibit a hormetic response.

Inhalable dust exposures, tasks, and use of ventilation in small woodworking shops: a pilot study.

Measures of workers' inhalable dust exposures, tasks, and ventilation use were made in five small woodworking shops prior to the start of an intervention effectiveness study aimed at lowering personal wood dust exposures. The data were used to (1) design a sampling protocol for an intervention success measure, (2) identify targets for intervention among the tasks and activities responsible for high dust levels, and (3) develop shop-level measures as tools for tailoring intervention activities. Geometric mean dust concentrations ranged from 1.6 to 9.9 mg/m3 in the five shops, with the highest levels occurring in a cabinet shop. All shops had centralized dust collection systems and workers generally used dust control on stationary tools (60-100% of the time) when it was available. Sanding with both stationary and handheld powered tools, cleaning with methods that can disperse dust (e.g., brushes, compressed air), and miscellaneous tasks were all responsible for significant personal exposures. The positive association between miscellaneous tasks and exposures probably reflects the high background levels generated by nearby processes. Sanding with both stationary tools and handheld powered tools represents the most significant influence on personal exposures in small woodworking shops. The authors conclude that pilot studies are useful tools for designing occupational health and safety intervention effectiveness studies.

Occupational health and safety in household hazardous waste management facilities.

Employees in household hazardous waste management facilities encounter a variety of potentially hazardous exposures. The purpose of this study was to evaluate both chemical and physical hazards at a representative group of household hazardous waste management facilities in Minnesota. Sampling results suggest that chemical exposures are generally not a problem when chemical bulking is performed outside the facility. For facilities operating year-round, however, proper ventilation is necessary to ensure adequate control of chemical exposures when bulking is done inside the building. The most significant chemical exposures occurred when handling paint (benzene) and broken fluorescent light bulbs (mercury). Guidelines for appropriate personal protective equipment and handling of broken fluorescent light bulbs were developed as a result of this study. Materials handling was the most significant physical hazard, resulting in wrist, elbow, and back injuries. The suspected reasons for these injuries (awkward postures and repetitive motions) were noted throughout the management process and should be further investigated.

Selecting respirators for control of worker exposure to infectious aerosols.

A method for selecting respirators for protection in infectious aerosol environments was developed, building on a procedure used to choose respiratory protection for environments containing nonbiological contaminants. Modifications in the traditional respirator selection method are proposed for situations where information on occupational exposure limits, toxicity, and airborne concentrations is absent. Toxicity is determined from risk rankings proposed by a variety of organizations. The nature of the activity allows assessment of source generation, which is combined with room volume and airflow to obtain a ranking of airborne concentration. Finally, concentration and toxicity ranks determine a minimum assigned protection factor, which corresponds to a respirator class. Case studies are presented to illustrate the proposed decision logic. For each situation, the procedure yielded choices that were both protective and reasonable. These results suggest that the procedure will be applicable to a variety of settings for a range of infectious organisms.

Improved methods for generation, sampling, and recovery of biological aerosols in filter challenge tests.

In preparation for filter efficiency tests and sampler comparison studies, methods of biological aerosol generation, sampling, and filter recovery were modified from previous studies. Methods described include (1) techniques for generating aerosols that reduced nuisance particles to negligible levels and increased the cell culturability of Mycobacterium abscessus by 30%, (2) sampling techniques that lowered the detectable range of biological particle size from 0.65 to 0.45 micron and reduced the sampling flow from the chamber from 28.3 to 1.5 L/min, and (3) development of methods to remove culturable organisms from respirator filter media. These methods were developed for filter challenge tests with M. abscessus and were applied to two other bacteria. They may also have application to a wider variety of organisms and bioaerosol assessments.

Aerosol penetration behavior of respirator valves.

Exhalation and inhalation valves from half-facepiece negative pressure respirators were evaluated for leakage during an 8-hour cyclic breathing test period using two work rates (415 and 622 kg-m/min) and two particle sizes (0.3 and 0.8 micron). Three different models (manufacturers) of exhalation valves were tested, with two lots for each model. Exhalation valve leakage ranged from 0.0 to 0.03%; no failure of exhalation valves occurred. No differences in lot or manufacturer were found. Differences in particle size did not lead to differences in penetration at the lower work rate; at the higher work rate 0.3-micron particles were less penetrating than 0.8-micron particles (0.03 versus 0.06%). When tested for air leakage at a pressure of 2.54 cm H2O, following the National Institute for Occupational Safety and Health certification method, exhalation valves exhibited no leakage either before or after the experiments. Inhalation valves averaged 20% leakage for all experiments; 0.3-micron particles were again less penetrating (13%) than 0.8-micron particles (27%). No inhalation valve failure occurred. No differences in lot (within manufacturer) were found; there were, however, significant differences in particle penetration among the three manufacturers' inhalation valves. Airflow leakage through the inhalation valves did not change during the experimental period, but differed among the three manufacturers. Measurements using airflow leakage and particle penetration produced the same ranking for the three manufacturers' inhalation valves.

Collection of three bacterial aerosols by respirator and surgical mask filters under varying conditions of flow and relative humidity.

A variety of respirator filters and surgical masks were challenged with three aerosolized bacteria: Mycobacterium abscessus (M.a.) (a rod), Staphylococcus epidermidis (S.e.) (a sphere), and Bacillus subtilis (B.s.) (a rod). Tests were conducted at two flow rates (45 and 85 l./min) and two humidity levels (30 and 70%). Aerosols were measured with a total-particle, direct-reading, spectrometer and a viable particle cascade impactor. Measurements up- and downstream of the filter or mask were used in determining aerosol penetration; respirator or surgical mask fit was not evaluated. Bioaerosol penetration measured with two aerosol sampling instruments was found to correlate. Additionally, bioaerosol test parameters were evaluated with respect to their effect on penetration. Increasing flow resulted in increased penetration of all organisms while an increase in relative humidity did not exert a consistent effect on all organisms. Of the respirators approved by the National Institute for Occupational Safety and Health (NIOSH), filter efficiency was as expected with dust/mist respirators having the lowest and HEPA filters the highest efficiency. Surgical masks were the least efficient of all filters tested; these are not certified by NIOSH. Bioaerosol penetration was compared to that of a polystyrene latex sphere (PSL) aerosol. Penetration of the test aerosols was predicted on the basis of particle aerodynamic diameter and was expected to be in this order: PSL > M.a. > S.e. = B.s. The PSL aerosol was the most penetrating, as predicted. However, results showed that B.s. was more penetrating than S.e. The aerodynamic diameter may not be the best parameter for predicting aerosol penetration of non-spherical particles in these filters.

An evaluation of respirator maintenance requirements.

A telephone survey was developed as part of a pilot study to evaluate the inspection, cleaning, maintenance, and storage aspects of respirator protection programs (RPP). Regulations and consensus standards such as those published by the Occupational Safety and Health Administration in the Code of Federal Regulations (CFR) or the American National Standards Institute (ANSI) require or recommend that RPP contain elements that ensure that the respirators provide proper protection. A great deal of research has been done to evaluate the effectiveness of new respirators; however, little research has been conducted to evaluate how respirators behave over time in real industrial settings Respirator inspection, cleaning, maintenance, and storage are significant factors in determining how well a respirator continues to perform. The telephone survey was developed by reviewing the requirements and recommendations of CFR 1910.134 and ANSI Z88.2-1980. Approximately 30 companies were selected based on their use of negative air-purifying respirators. Most of the companies represented the hardgoods manufacturing or service industries. Although the majority of companies were meeting requirements, responses indicated that the following improvements in RPP were necessary: (1) inspection of all respirator parts should be carried out before and after each use, (2) replacement parts should be made readily available on site, (3) regular cleaning should be performed, and (4) more hands-on practice with respirators and their maintenance should be incorporated into training sessions.

Exposures to inhalable and "total" oil mist aerosol by metal machining shop workers.

Several recent studies have compared worker personal aerosol exposures as measured by the current method with those obtained by a new approach based on collecting the inhalable fraction, intended to represent all the particles that are capable of entering through the nose and/or mouth during breathing. The present study investigated this relationship for a metal machining facility where aerosols were generated from severely refined, nonaqueous ("straight") cutting oils used during the lathe working of metal rod stock. Workers (n = 23) wore two personal aerosol samplers simulataneously, one of the 37-mm type (for "total" aerosol exposure, E37) and the other of the Institute of Occupational Medicine (IOM) type (for inhalable aerosol exposure, EIOM). The data were analyzed by weighted least squares linear regression to determine the coefficient S in the relation EIOM = S.E37. It was found that S = 2.96 +/- 0.60. This ratio-in which exposure to inhalable aerosol was greater than to "total" aerosol-is consistent with previous observations in other industries. The relative coarsenss of the oil mist aerosol, as estimated by cascade impactor measurements, probably explains the difference between the sampling methods. The collection of large "splash" droplets, may also contribute. Future occupational aerosol standards for metalworking fluids will be based on the new, health-related criteria, and exposures will be assessed on the basis of the inhalable fraction. Results of studies like that described here will enable assessment of the impact on future workplace aerosol exposure assessments of introducing new standards.

Studies of ventilation efficiency in a protective isolation room by the use of a scale model.

OBJECTIVE: To assess the ability of a protective isolation room ventilation system to reduce patient exposure to airborne infectious agents, using a small-scale model that permits cost-effective and unobtrusive study of relevant indices of performance. DESIGN: A one-half scale model of a protective isolation room at the University of Minnesota Hospital was constructed and equipped for tracer gas experiments to assess ventilation efficiency. MEASUREMENTS: Tracer gas (SF6) was injected into the model supply air. Tracer gas concentration was recorded over time and analyzed to determine local and room mean age of air. Age of air is a direct measurement of ventilation efficiency and can be used to predict patient exposure to contamination. RESULTS: Although for the room taken as a whole, ventilation efficiency was close to 50% (a value corresponding to perfect mixing), the experimental results for the local mean age of air indicate that some parts of the model were ventilated much better than others. CONCLUSION: Room air exchange rate is only one parameter useful in assessing ventilation in patient areas. Effective distribution of ventilation air also is critical to the control of airborne contamination. Areas of the room with poor ventilation would be expected to have higher concentrations of airborne infectious agents and other contaminants. Patient exposure can be minimized by placing the patient in well-ventilated areas of the room. Improved ventilation designs may reduce patient exposure further without increasing actual airflow rate.

Results of a survey to assess curriculum needs for academic training programs in hazardous substances.

With the advent of new industrial hygiene academic training programs in hazardous substances, located at nine United States universities, a curriculum needs assessment survey was developed at the University of Minnesota and completed by members of the joint American Industrial Hygiene Association/American Conference of Governmental Industrial Hygienists Hazardous Waste Committee and members of the Health and Safety Subcommittee of the Hazardous Waste Action Coalition. The survey asked respondents to indicate whether 27 course subjects (1) should be required, (2) may be required or elective, (3) should be elective, or (4) should not be offered. Respondents were also asked to recommend additional course subjects, research needs in the hazardous materials and waste field, and certifications to be pursued. Results from 50 completed surveys (50% response rate) showed that about half of the respondents work for consulting companies and have more than 15 years of experience in the hazardous material or waste field. The courses receiving the most "required" responses included (1) the relevant regulations, (2) worker training in health and safety, (3) waste management technology, (4) pollution prevention, and (5) treatment technology. Of elective subjects, respondents recommended education in communications, public affairs, negotiations and conflict resolution, property inspection, government relations, and air pollution modeling. Respondents indicated the strongest research needs were in the areas of direct reading instruments (improved versions and their use for personal exposure monitoring) and heat stress management of personnel wearing protective clothing. Respondents felt that the best qualifications to pursue after graduation were the Certified Industrial Hygienist designation alone, or in combination with the Certified Safety Professional designation.

Evaluation of single-use masks and respirators for protection of health care workers against mycobacterial aerosols.

BACKGROUND: The recent increase in multidrug-resistant tuberculosis has spawned a major controversy concerning the degree of respiratory protection needed by health care workers, particularly during sputum-inducing procedures. The objective of this study was to measure the filtration efficiencies of a single-use submicron surgical mask, two disposable dust/mist respirators, a dust/mist/fume respirator, and a high-efficiency particulate air respirator against aerosolized mycobacteria. Facial fit was not addressed. METHODS: In a specially designed enclosed test apparatus, an aerosol was generated with a Collison nebulizer from a known concentration of Mycobacteria chelonae, used as a surrogate for Mycobacterium tuberculosis. Aerosol concentrations were measured with Anderson samplers upstream and downstream of the test masks and respirators, which were heat sealed to a metal plate. RESULTS: Mean efficiencies ranged from approximately 97% for the surgical mask and a dust/mist respirator to more than 99.99% for the high-efficiency particulate air respirator. Measurements of filter efficiency with an Aerodynamic Particle Sizer for the M. chelonae aerosol and independent challenge tests with latex spheres correlated closely with measurements of M. Chelonae collection efficiency determined with Andersen samplers. CONCLUSIONS: Analysis of variance and Tukey's method for multiple comparisons indicated that the dust/mist/fume respirator and the HEPA respirator collected M. chelonae with significantly greater efficiency than did either the surgical mask or the dust/mist respirator. Even the least efficient mask tested, however, had a filter efficiency of more than 97% against particles averaging less than 1 micron in aerodynamic diameter.

An empirical model for estimating the collection efficiency of dust-mist respirators.

This paper compares experimental measurements of filter performance with predictions of aerosol collection by dust-mist respirators using the single fibre efficiency model and an empirical model developed by the authors. The former, a theoretically-based semi-empirical model, indicates that mechanical phenomena such as impaction, interception and diffusion are responsible for only a fraction of the collection efficiency of dust-mist respirators, i.e. 30-70% depending on particle size. The difference between these relatively low predicted efficiencies and experimentally observed values, which were greater than 95%, can be attributed to electrostatic forces. Because it was not possible to determine filter fibre charge the single fibre efficiency model could not be used to predict electrostatic collection. An empirical model developed from experimental data with monodisperse latex aerosols was used to predict silica and asbestos collection. The empirical model adequately described silica collection, but predicted much higher asbestos penetration than was observed experimentally.

Collection of silica and asbestos aerosols by respirators at steady and cyclic flow.

Air purifying dust/mist respirators are presently tested using a silica aerosol under conditions of steady flow. In experiments, the predictive validity of such tests was evaluated by testing respirators using silica and asbestos aerosols under conditions of both steady and cyclic flow. Silica penetration at steady flow was reasonably predictive of silica penetration under cyclic flow. However, asbestos penetration under cyclic flow was not predicted well by penetration of either silica or asbestos at steady flow. Furthermore, the potential for exhalation valve failure under cyclic flow was identified. Current NIOSH protocols for evaluating respirator performance should be reconsidered in light of these findings.

Collection efficiency of respirator filters challenged with monodisperse latex aerosols.

Collection efficiency was evaluated for 10 respirator manufacturers' electrostatically-charged dust/mist filters challenged with eight sizes of latex spheres in a range representative of the silica aerosol used in National Institute for Occupational Safety and Health (NIOSH) certification tests. Minimum efficiency occurred at or below the smallest size of 0.102 microns. Appreciable differences were found in the performances of filters distributed by the 10 manufacturers. Filters produced by 1 manufacturer exhibited significantly lower collection efficiency than other filters tested; those produced by 2 manufacturers performed somewhat better than the others tested. Statistical evaluation of Weibull-transformed data using analyses of covariance and Tukey's significant difference test allowed classification of the 10 manufacturers into three performance categories.