Video exposure assessments demonstrate excessive laboratory formaldehyde exposures.

Video exposure assessments were conducted in a comparative anatomy laboratory using formaldehyde-preserved sharks and cats. Work in the facility using time-integrated samplers indicated personal and area concentrations generally below the current OSHA permissible exposure limit. However, complaints about room air quality were frequent and routine. Using a photoionization detector with an integral data logger, total ionizables present were sampled as a surrogate for formaldehyde. After synchronizing time tracks from the datalogger concentrations with simultaneously created videotapes of laboratory tasks, composite video exposure overlays were generated. Use of this video exposure method revealed very short-lived, excessively high peak exposure events, whereas conventional time-weighted averages indicated the majority (30/32) of personal exposures were below the OSHA limit of 0.75 ppm. These legally acceptable exposure levels were associated with self-reported symptoms of burning nose and eyes and eye irritation. Thus, transient peak formaldehyde concentrations not detected by longer term averaging studies could be responsible for the health effects reported. The video exposure monitoring method demonstrated that close dissection work, opening peritoneal cavities, and specimen selection activities were most likely the causes of elevated student exposures. Teaching assistants' exposures were the highest, exceeding OSHA limits on several occasions. The utility of the video monitoring method for conducting enhanced, critical task exposure assessments is discussed.

Engineering controls for furniture strippers to meet the OSHA methylene chloride PEL.

This case study demonstrates how methylene chloride exposures during furniture stripping can be reduced to below the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 25 ppm (as an 8-hour time-weighted average). Five surveys were conducted at one facility; the first four resulted in employee exposure geometric means from 39 to 332 ppm. For the fifth survey local exhaust ventilation was used at the stripping tank and the rinsing area, which together exhausted 138 m3/min (4860 ft3/min). Additional controls included providing adequate make-up air, adding paraffin wax to the stripping solution, raising the level of the stripping solution in the tank, and discussing good work practices with the employee. The employees' methylene chloride exposures during the fifth survey resulted in a geometric mean of 5.6 ppm with a 95% upper confidence limit of 8.3 ppm, which was found to be significantly lower than the OSHA PEL and the OSHA action level of 12.5 ppm. The cost of the ventilation system was $8900.

An evaluation of retrofit engineering control interventions to reduce perchloroethylene exposures in commercial dry-cleaning shops.

Real-time monitoring was used to evaluate the ability of engineering control devices retrofitted on two existing dry-cleaning machines to reduce worker exposures to perchloroethylene. In one dry-cleaning shop, a refrigerated condenser was installed on a machine that had a water-cooled condenser to reduce the air temperature, improve vapor recovery, and lower exposures. In a second shop, a carbon adsorber was retrofitted on a machine to adsorb residual perchloroethylene not collected by the existing refrigerated condenser to improve vapor recovery and reduce exposures. Both controls were successful at reducing the perchloroethylene exposures of the dry-cleaning machine operator. Real-time monitoring was performed to evaluate how the engineering controls affected exposures during loading and unloading the dry-cleaning machine, a task generally considered to account for the highest exposures. The real-time monitoring showed that dramatic reductions occurred in exposures during loading and unloading of the dry-cleaning machine due to the engineering controls. Peak operator exposures during loading and unloading were reduced by 60 percent in the shop that had a refrigerated condenser installed on the dry-cleaning machine and 92 percent in the shop that had a carbon adsorber installed. Although loading and unloading exposures were dramatically reduced, drops in full-shift time-weighted average (TWA) exposures were less dramatic. TWA exposures to perchloroethylene, as measured by conventional air sampling, showed smaller reductions in operator exposures of 28 percent or less. Differences between exposure results from real-time and conventional air sampling very likely resulted from other uncontrolled sources of exposure, differences in shop general ventilation before and after the control was installed, relatively small sample sizes, and experimental variability inherent in field research. Although there were some difficulties and complications with installation and maintenance of the engineering controls, this study showed that retrofitting engineering controls may be a feasible option for some dry-cleaning shop owners to reduce worker exposures to perchloroethylene. By installing retrofit controls, a dry-cleaning facility can reduce exposures, in some cases dramatically, and bring operators into compliance with the Occupational Safety and Health Administration (OSHA) peak exposure limit of 300 ppm. Retrofit engineering controls are also likely to enable many dry-cleaning workers to lower their overall personal TWA exposures to perchloroethylene.