Roy M. Buchan

Aerosol Sampling Efficiency of 37 mm Filter Cassettes

This research compared the sampling efficiencies of open- and closed-face 37 mm filter cassettes and an experimental cassette with a tapered inlet. The experiment involved challenging the cassettes with various aerosol sizes up to 24 micron Mass Median Aerodynamic Diameter (MMAD) in a wind tunnel operated at 100 cm/sec. Sampling efficiencies were determined by comparing cassette mass concentration measurements to paired isokinetic samples. It was found that sampling efficiencies dropped with increasing particle size and that the cassette with the tapered entry offered no improvement to sampling efficiency. Sampling efficiency appeared to be improved by placing cassettes on a manikin to simulate personal sampling.

Field Evaluation of a Portable Photoionization Detector for Assessing Exposure to Solvent Mixtures

To evaluate a portable photoionization detector for assessing personal exposure to solvent mixtures, a set of 26 side-by-side, time-weighted average (TWA) personal breathing zone samples were collected during various construction painting tasks by two different sampling methods: (1) standard charcoal sorbent tubes analyzed by gas chromatography (CST/GC), and (2) a direct-reading photoionization detector coupled with an extended data-logger (PID). The TWA concentrations of the hydrocarbons detected by CST/GC analysis were summed for comparison with the TWA concentration obtained from the direct-reading PID. Based on linear regression between the log TWA concentrations of the two sampling methods, the data were highly correlated (r2 = 0.95). Since the solvents had effects that may be considered additive, threshold limit values (TLVs) for mixtures were developed using American Conference of Governmental Industrial Hygienists formulas to evaluate solvent exposure. The logs of the TLV mixture data from the sampling methods were highly correlated (r2 = 0.94). Based on the linear regression analyses, the response of the portable PID was highly correlated to the CST/GC results for hydrocarbon mixtures encountered during various painting tasks. Due to the short duration of tasks, highly fluctuating exposures, and complexity of the mixtures, the PID may provide the most cost-effective, detailed exposure assessment for solvent mixtures.

Effect of Waste Anesthetic Gas and Vapor Exposure on Reproductive Outcome in Veterinary Personnel

Elevated rates of adverse reproductive outcome among medical and dental personnel exposed to waste anesthetic gas and vapor have been noted in the literature. NIOSH issued recommended standards for occupational exposure to these agents in a criteria document published in 1977. This study was designed to investigate adverse reproductive outcome in veterinary personnel who are exposed to waste anesthetic gas and vapors at levels near the NIOSH recommended standards. This epidemiologic study employed case-control methodology using a national sample of male veterinarians, female veterinarians and female veterinary assistants. Occupational exposure to waste anesthetic gas and vapors was not found to be associated significantly with adverse reproductive outcome at the 95% confidence level for female veterinary personnel when adjustment was made for use of diagnostic x-rays. Use of diagnostic x-rays in veterinary practice was associated with a statistically significant increase in odds ratios for spontaneous abortion in female veterinarians and veterinary assistants.

Respirator Fit and Facial Dimensions of Two Minority Groups

Abstract The seal of a respirator to a workers face can be influenced by the workers facial dimensions. Males and females of the same and different racial/ethnic backgrounds exhibit different facial dimension measurements. This research was conducted to ascertain the relationship between facial dimensions influenced by race/ethnicity and gender to respirator fit. Facial dimensions and respirator fit were measured on 186 subjects from three racial/ethnic groups: 34 white American females, 32 white American males, 29 African-American females, 29 African-American males, 30 Mexican-American males, and 32 Mexican-American females. Fourteen facial dimension measurements were measured on each subject. A multiple analysis of variance indicated that facial dimensions between gender and race/ethnicity were significantly different (p = 0.0001). Quantitative fit tests were performed on each subject using the TSI PortaCount™ and MSA Advantage half-mask, air-purifying respirators. Subjects were fit with a small, medi...

Quantification of Air Contaminants at a Municipal Sewage Sludge Composting Facility

Abstract In 1993 there were an estimated 4000 employees working at 321 municipal composting facilities in 46 states. This work force may be exposed to dusts of biological origin, various gases, and airborne heavy metals. This study was designed to quantify contaminant concentrations at the Longmont, Colorado, composting facility. Sampling was divided into two phases. Phase I took place from June 12 through June 16, which was the facilitys time period for peak volume. Phase II occurred from August 14 through August 18. Total dust concentrations as high as 173.79 mg/m3 were measured. The geometric means of total dust samples on days with screening and sweeping operations were 23.05 and 35.19 mg/m3. The mass median aerodynamic diameter (MMAD) of the aerosol was approximately 4.0 μm. The high dust concentrations coupled with the small MMAD indicate a possible occupational health risk from dust exposure at this municipal composting facility. Endotoxin concentrations varied from 28.9 to 5930.6 ng/m3. Using reg...

Ambient total suspended particulate matter and benzo (a) pyrene concentrations from residential wood combustion in a mountain resort community

This research investigated community air pollution in Telluride, Colorado, resulting from particulate matter emissions generated by residential wood combustion. Total suspended particulate matter and benzo (a) pyrene (BaP) concentrations were highest in the center of town, averaging 61 µg/m3 and 7.4 ng/m3, respectively. The mean BaP level of 7.4 ng/m3 appears to be several times greater than that which would be expected in a major metropolitan area. Residential wood combustion is suspected as the primary source of BaP in this community.

Pulmonary Reactive Components of Winter Wheat Grain Dust at Colorado Farms and Elevators

Abstract Surveys were conducted during the 1992 and 1993 harvests and the intervening winter shipping season to characterize the pulmonary reactive dust components and exposure concentrations at wheat farms and country elevators in Colorado. The following parameters were measured or identified: respirable dust (RD) and respirable silica (RS) by the 10-mm cyclone; total dust concentration (TDC) and particle mass median aerodynamic diameter (MMAD) by personal cascade impaction and gravimetric analysis; organophosphate pesticides (OPs) by gas chromatography; microbial colony-forming units (CFU) per cubic meter for mesophilic (F) and thermotolerant fungi (TF), total bacterial plate count (TPC), and gram-negative bacteria (GNB) by standard microbial culture techniques; and bacterial endotoxin units/m3 (EU/m3) by the Limulus amoebocyte lysate test. Airborne fungi, GNB, and arthropods present during harvest and storage were identified by morphological and/or chemical characteristics. Mean concentrations found at...

Characterization of Particleboard Aerosol — Size Distribution and Formaldehyde Content

Health hazards unique to particleboard include the generation of urea-formaldehyde resin bound in wood aerosol and release of formaldehyde gas that can be inhaled by the worker. A particleboard aerosol was generated by a sanding process and collected under laboratory conditions that determined the particle size distribution and formaldehyde content. Three side-by-side Marple 296 personal cascade impactors with midget impingers attached downstream collected particleboard aerosol and gaseous formaldehyde for ten sample runs. Gravimetric analysis quantified the collected aerosol mass, and chromotropic acid/spectrophotometric analytical methods were employed for formaldehyde content in particleboard aerosol and gaseous formaldehyde liberated from sanded particleboard. Significant variations (p less than .005) were observed for the particleboard mass and gaseous formaldehyde collected between sample runs. No significant differences (alpha = .05) were observed for the aerosol size distribution determined and formaldehyde content in particleboard aerosol per unit mass for sampling trials. The overall MMAD of particleboard aerosol was 8.26 microns AED with a sigma g of 2.01. A predictive model was derived for determining the expected formaldehyde content (microgram) by particleboard aerosol mass (mg) collected and particulate size (micron AED).

Total Dust, Respirable Dust, and Microflora Toxin Concentrations in Colorado Corn Storage Facilities

To aid in the process of characterizing corn dust exposures on farms and in elevators in northeastern Colorado, several parameters were examined. Total dust and respirable dust samples were collected and evaluated. Potentially dangerous dust components evaluated were respirable silica, endotoxin, and mycotoxin levels. Many of the total dust samples (58%) would have exceeded 8-hour time-weighted average (TWA) had sampling been conducted for 8 hours; on farms the operation takes between two and four hours. The same statement may be made for respirable dust samples collected for this project. Nearly 33 percent of the respirable dust samples collected would have exceeded the Occupational Safety and Health Administration (OSHA) TWA had sampling been conducted over an 8-hour period. Respirable silica standards were exceeded at 25 percent of the sampling locations. Presence of mycotoxins at all sites was confirmed by the use of ELISA kits. The most significant finding of this study was high levels of endotoxin at several of the sampling sites. Eighty-five percent of the sampling locations had endotoxin levels above 500 EU/m3. One location, Farm 4, had endotoxin levels of above 1.7 million EU/m3.

Exposure to Ribavirin Aerosol

Abstract The antiviral drug ribavirin is administered as an aerosolized mist via nasal and oral inhalation for the treatment of respiratory syncytial virus (RSV) to highly compromised infants and young children. The excess aerosol is exhausted directly into the patient treatment room, potentially exposing anyone who enters. Since the drug has demonstrated teratogenic effects in animal toxicity studies, exposure of women of child-bearing age to ribavirin is contraindicated. The population at risk includes female physicians, nurses, respiratory therapists, other hospital staff, and patient visitors (e.g., family members). In Phase One of this study, ribavirin aerosol was characterized with cascade impaction, revealing a mass median aerodynamic diameter (MMAD) of 1.0 mm. Ribavirin aerosol is produced by a Small Particle Aerosol Generator (Model SPAG-2). Changes in the SPAG-2 output concentration as a function of time and the corresponding changes in hospital treatment room air concentrations were evaluated. ...