Biomedical subjects

R K Oestenstad

Publications and source records attributed to R K Oestenstad.

7 recordsLinked to original sources

PubMed2001

A practical approach to exposure assessment programs in the private sector: a partial validation study of a qualitative chemical exposure assessment model.

Utilizing a computer-based exposure assessment program, a United States-based chemical company was able to predict which chemicals and tasks presented the greatest probability of exposure in the workplace. The data generated by the model also enabled the company to prioritize these tasks for quantitative exposure monitoring. The assessment program addressed potential chemical exposure to workers in a cost-effective way. This assessment program reduced a facility's cost of complying with the Occupational Safety and Health Administration (OSHA) standard by about 90 percent. Overall, the program reduced the company's cost by about $700,000 when compared to traditional methods used for achieving compliance with these regulations. In addition, by utilizing a computer-based approach, a facility did streamline its chemical exposure assessment process. A comparative evaluation study was conducted in conjunction with a graduate research project. The purpose of the study was to compare the company's qualitative exposure assessment model with several other exposure assessment models. The project compared hazard rankings calculated from three exposure assessment models with actual exposure data for three work scenarios. Overall, the models appeared to be predictive of measured exposures. Therefore, they can be useful tools to help make decisions on which exposures have the highest potential to cause occupational illness to employees and therefore require additional monitoring and follow-up.

Chemical Industry↗

PubMed1995

Beyond air quality--factors that affect prevalence estimates of sick building syndrome.

If the prevalence of sick building syndrome (SBS) is estimated before intervention begins, then a reduction in the estimate may later be used to measure success of the intervention, and in particular, those efforts toward improving air quality. However, the measure of success will be distorted if factors other than air quality affect the SBS prevalence estimate. In this study the background prevalence of SBS was estimated and study factors identified that alone affected the estimate. Two symptom questionnaires were randomly administered to workers from 39 offices before routine physical examinations; one questionnaire described the SBS study, the other did not. SBS was defined as a symptom in the prior 24-hour or 7-day recall period that was more severe at work and not related to suspected confounders--allergy, cold, flu. Prevalence and prevalence ratios were estimated along with 95% confidence intervals (CI). Symptoms were reported by 45% of 1088 workers surveyed, but most reported them as more severe outside work or related them to confounders. SBS prevalence was 5%. It was 3.2 times higher (95% CI: 1.8, 5.7) among workers cognizant of the study relative to those blinded, 2.2 times higher (95% CI: 1.2, 4.1) for the 7-day relative to the 24-hour recall period, and 2.5 times higher (95% CI: 1.4, 5.0) for females. SBS prevalence did not differ by workday or age. Since study factors alone affected prevalence estimates, a standardized assessment method seems necessary for SBS.

Confounding Factors, Epidemiologic↗

PubMed1992

An assessment of critical anthropometric dimensions for predicting the fit of a half-mask respirator.

The purpose of this study was to determine if facial dimensions for a group of subjects were predictive of the fit factors measured while one brand of half-mask respirator was worn. Fit factors and 12 facial dimensions measured on 30 female and 38 male subjects were analyzed by correlation coefficients; weighted, multiple linear regression; and discriminant analysis. Data were analyzed for all subjects, gender subgroups, a race subgroup (whites only), and race/gender subgroups. Significant correlation coefficients with the log-transformed fit factors were found for four dimensions; four dimensions had significant coefficients in four or more multiple linear regression models. Only two dimensions had significant coefficients in four or more discriminant analysis models. Menton-subnasale (lower face) length was the only dimension included in all three of these groups. Gender-specific regression models had very high coefficient of determination values (R2 > 0.85). Discriminant analysis of the data for all subjects and race/gender subgroups found very good predictive scores for statistical software-generated models and menton-subnasale length alone; these scores were significantly better than those for the model with the respirator test panel dimensions (face length and lip width). These analyses found that facial dimensions were good predictors of respirator fit for those subjects wearing one brand of half-mask respirator. Lower face length was consistently indicated as being correlated or associated with fit. These results would indicate that dimensions other than those currently used may be more appropriate to define a half-mask respirator test panel.

Adult↗

PubMed1990

Identification of faceseal leak sites on a half-mask respirator.

A method has been developed to identify the location and shape of respirator faceseal leak sites by the deposition of a fluorescent tracer. An aerosol generation, conditioning, and exposure system to provide a test environment with stable aerosol concentration and size distribution of 4-methyl-7-diethylaminocoumarin was designed and tested. Faceseal leak sites on a respirator mounted on a mannequin and worn by human subjects were identified by deposition of the tracer aerosol and subsequent observation under long-wave ultraviolet lighting. Test parameters were identified for the optimal definition of leaks. Photographic techniques were developed to document the identified leak sites.

Adult↗

PubMed1990

Distribution of faceseal leak sites on a half-mask respirator and their association with facial dimensions.

Faceseal leaks on one brand of half-mask respirator worn by 73 human subjects were identified by deposition of a fluorescent tracer aerosol during a standard quantitative fit test. The identified leaks were categorized according to their location and shape. It was found that about 89% of all observed leaks occurred at the nose or chin or were multiple leaks which included these sites. Fit factors for these types of leaks were significantly lower than for other types of leaks. About 73% of all leaks approximated the shape of a slit rather than a round orifice, and the prevalence of these leaks was affected by gender. Significant association of facial dimensions and leak sites were found. Most of these were attributed to differences in gender, and only a very small percentage were for the facial dimensions used to define the Los Alamos respirator test panel. Significant correlation of facial dimensions and fit factor were found for only three facial dimensions; none of which are used to define the test panel. Evidence of airflow streamlining within the facepiece was observed on 22% of the subjects. Results of this study indicate that respirator leakage is strongly affected by nose and chin leaks, that gender is a factor in how a respirator fits, and that consideration should be given to including nasal dimensions when defining a respirator test panel and selecting a respirator for an individual wearer.

Adult↗

PubMed1986

An evaluation of the K2 asbestos screening test.

The predictive ability of the K2 Asbestos Screening Test was determined by comparing the results obtained with the test and confirming analysis by polarizing light microscopy on 90 bulk insulation samples. The test yielded 38.9% true positives, 4.4% true negatives, 56.7% false positives and 0% false negatives. The proportion of false positives was significantly different from that reported by the researchers who developed the test and found that the test would not yield false positives. The results of this study are similar to those reported in a previous evaluation of the test. It was concluded that the screening test is not an effective screening tool because of the high proportion of false positives, as reflected by marginal values of specificity and positive predictive value. It was noted that problems with the test might result from failure of the wash steps to adequately remove positive interferences apparently associated with gypsum and mineral wool. Problems in interpreting color changes were noted also.

Alabama↗

PubMed1983

The effect of the growth of facial hair on protection factors for one model of closed-circuit, pressure-demand, self-contained breathing apparatus.

Protection factors for one model of closed-circuit, pressure-demand, self-contained breathing apparatus were determined for eight volunteers while clean-shaven and at approximately two-week intervals during an eight-week, beard-growth period. Measurement of facepiece leakage was patterned after the DOP quantitative fit test method outlined in ANSI Z88.2-1980. Comparison of results indicated that beard growth had a profound adverse effect on the amount of protection provided.

Analysis of Variance↗