Respiratory protection as a function of respirator fitting characteristics and fit-test accuracy.

The fitting characteristics of particulate respirators are no longer assessed in the National Institute for Occupational Safety and Health respirator certification program. It is important for respirator program administrators to understand the implications of that change and the additional burden it may impose. To address that issue, a typical respirator fit-testing program is analyzed using a mathematical model that describes the effectiveness of a fit-testing program as a function of the fitting characteristics of the respirator and the accuracy of the fittesting method. The model is used to estimate (1) the respirator assignment error, the percentage of respirator wearers mistakenly assigned an ill-fitting respirator; (2) the number of fit-test trials necessary to qualify a group of workers for respirator use; and (3) the number of workers who will fail the fit-test with any candidate respirator model and thereby fail to qualify for respirator use. Using data from previous studies, the model predicts respirator assignment errors ranging from 0 to 20%, depending on the fitting characteristics of the respirator models selected and the fit-testing method used. This analysis indicates that when respirators do not necessarily have good fitting characteristics, respirator program administrators should exercise increased care in the selection of respirator models and increased care in fit-testing. Also presented are ways to assess the fitting characteristics of candidate respirator models by monitoring the first-time fit-testing results. The model demonstrates that significant public health and economic benefits can result when only respirators having good fitting characteristics are purchased and respirators are assigned to workers using highly accurate fit-testing methods.

Manganese dioxide exposures and respirator performance at an alkaline battery plant.

Two industrial hygiene studies were conducted at an alkaline battery plant to evaluate worker exposures to manganese dioxide particulate and the effectiveness of filtering facepiece respirators. The work areas studied included the plant's powder-processing tower and press rooms where manganese was blended, compacted with graphite, and inserted into battery cans. Full-shift personal breathing zone monitoring was conducted to estimate manganese dust exposures of press operators, mechanics, and material handlers. In-facepiece and personal breathing zone air sampling pairs were also collected using a program protection factor protocol to estimate the protection provided by the respirators. Particle size evaluations were made using nylon cyclones and Marple personal multi-stage impactors. All samples were analyzed for manganese by inductively coupled argon plasma, atomic emission spectroscopy via NIOSH analytical method 7300 utilizing a modified acid digestion procedure. Fifty-four, full-shift, time-weighted average (TWA) exposures to total manganese ranged from 0.1 to 5.4 milligrams per cubic meter (mg/m3); worker exposures were substantially lower during a follow-up study due to engineering control improvements. Concurrent area sample comparisons of total and respirable manganese revealed that the respirable particulate mass fractions ranged from 6 to 32 percent, and mass median aerodynamic diameters determined from personal breathing zone air samples were mostly greater than 10 micrometers. Fifteen respirator performance evaluations were conducted using Moldex 2200 respirators fitted with 25 millimeter cassettes and light weight sampling probes. Protection factors ranged from 5 to 220, with a geometric mean and standard deviation of 31 and 2.97, respectively. The 5th percentile protection factor estimate was 5, as calculated from the protection factor distribution for this sample set. In 1995, the American Conference of Governmental Industrial Hygienists (ACGIH) lowered the elemental and inorganic manganese dust Threshold Limit Value (TLV) from 5 mg/m3 to 0.2 mg/m3 to address adverse pulmonary and central nervous system effects and male infertility. Although most personal breathing zone concentrations were above 0.2 mg/m3, none of the in-facepiece concentrations exceeded this concentration. Parkinson's-like symptoms have been reported in the literature for high manganese dust and fume exposures, but the importance of low dust exposures for producing neurological effects is uncertain.

Levels of carbon dioxide in helmet systems used during orthopaedic operations.

The use of isolation helmets has gained popularity as a method of possible protection of the operating-room personnel from diseases that can be transmitted during operative procedures. However, the use of these systems has been associated with a variety of symptoms, including fatigue, diaphoresis, nausea, headache, and irritability. These symptoms have often been attributed to the mental stress of the operative procedure or the physical discomfort of the helmet. As far as we know, no manufacturers include the measured levels of carbon dioxide or the rate of air exchange of their helmet system. A possible common cause of discomfort with helmet systems is the level of carbon dioxide to which the person wearing the device is exposed. We measured the levels of carbon dioxide in four helmet systems from three different manufacturers during light exercise designed to approximate the exertion during an orthopaedic operation. All but one unit failed to meet the exposure limits recommended by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration regarding exposure to carbon dioxide. One unit, the Stackhouse Freedom Aire self-contained system, did meet these standards, but the levels of carbon dioxide in this helmet were more than 1000 per cent greater than the ambient levels in air (440 parts per million compared with 4939 parts per million). Isolation systems must be evaluated carefully not only for comfort but also for the physiological effects caused by exposure to elevated levels of carbon dioxide. Operating-room personnel who use such systems should be aware that many of the physical symptoms that they experience may be associated with elevated levels of carbon dioxide.

Respiratory symptoms and pulmonary function in chicken catchers in poultry confinement units.

To evaluate the respiratory consequences of working in poultry confinement units, we completed a cross-sectional epidemiologic study of respiratory symptoms and pulmonary function in 59 chicken catchers. The results were compared to a published reference standard of nonexposed blue-collar workers. Chicken catchers reported a high rate of acute symptoms associated with work in poultry houses. They also reported statistically significant higher rates for chronic phlegm (39.0%) and chronic wheezing (27.1%) than nonexposed blue-collar workers. Chicken catchers had significant decrements over a work shift in forced vital capacity (-2.2%) and forced expiratory volume in 1 sec (-3.4%), and there was suggestive evidence that they had decreased preshift pulmonary function compared with nonexposed blue-collar workers. These results indicate that chicken catchers are at risk for respiratory dysfunction and emphasize the need to develop measures to minimize their exposure to respiratory toxicants in poultry confinement units.

Application of a pilot study to the development of an industrial hygiene sampling strategy.

An industrial hygiene pilot study was conducted to estimate the concentrations of respirable dust likely to be encountered during the personal sampling phase of a large-scale morbidity study of the portland cement industry. An analysis of the pilot study data showed little variability in exposure for subjects working in the same job in the same area of the same plant. Thus, one could estimate mean exposure by sampling several subjects rather than sampling the same subject several times. It was concluded that for statistical considerations, the best approach would be to sample four jobs per area and six subjects per job. Practical considerations required one more often to select six jobs with two subjects per job, however. Overall, the collection of fewer samples was required during the morbidity study than was anticipated originally. In turn, the reduction in the number of samples to be collected resulted in a savings of time and resources.

Sources of respiratory insult in the poultry processing industry.

Although the agricultural community has focused a great deal of attention on improving the overall health of poultry for production purposes, the health of poultry workers has, by comparison, received less direct attention. Recent studies suggest that poultry workers who come in direct contact with live birds may be at risk of pulmonary dysfunction, including the development of chronic respiratory diseases. Exposure of poultry workers to live birds results in potential pulmonary insult from a variety of allergenic and immunologic agents, as well as nuisance dust particles. In addition, marked levels of gram-negative bacterial endotoxins and antibiotic-resistant bacteria contaminate the occupational environment. Health care professionals should be aware of the potential sources of respiratory insult to workers in poultry processing and related industries.

Occupational exposure to airborne endotoxins during poultry processing.

Airborne gram-negative bacterial endotoxin levels were quantified in a live chicken hanging (shackling) room of a poultry processing plant. The mean respirable dust levels at the entrance and exit of the shackling line were 1.13 +/- 0.12 and 0.72 +/- 0.06 mg/m3, respectively, or approximately 6% of the total dust. Endotoxins constituted 43.3 +/- 2.8 micrograms per gram of respirable dust. Airborne endotoxins were present in the total dust at the mean level of 918.4 +/- 159.0 ng/m3 at the room entrance and 634.0 +/- 96.9 ng/m3 at the exit, with respirable levels of 44.3 +/- 7.8 and 33.6 +/- 2.2 ng/m3. Inhalation of gram-negative bacterial endotoxins can result in respiratory and systemic pathophysiology. The potential for adverse health effects in the working environment of the live poultry processing industry is discussed. Medical studies of workers in this area are required to confirm or deny the existence of occupationally related health effects.