Video Exposure Monitoring Research Articles

Direct-reading instruments for aerosols: A review for occupational health and safety professionals part 2: Applications

Direct reading instruments (DRIs) for aerosols have been used in industrial hygiene practice for many years, but their potential has not been fully realized by many occupational health and safety professionals. Although some DRIs quantify other metrics, this article will primarily focus on DRIs that measure aerosol number, size, or mass. This review addresses three applications of aerosol DRIs that occupational health and safety professionals can use to discern, characterize, and document exposure conditions and resolve aerosol-related problems in the workplace. The most common application of aerosol DRIs is the evaluation of engineering controls. Examples are provided for many types of workplaces and situations including construction, agriculture, mining, conventional manufacturing, advanced manufacturing (nanoparticle technology and additive manufacturing), and non-industrial sites. Aerosol DRIs can help identify the effectiveness of existing controls and, as needed, develop new strategies to reduce potential aerosol exposures. Aerosol concentration mapping (ACM) using DRI data can focus attention on emission sources in the workplace spatially illustrate the effectiveness of controls and constructively convey concerns to management and workers. Examples and good practices of ACM are included. Video Exposure Monitoring (VEM) is another useful technique in which video photography is synced with the concentration output of an aerosol DRI. This combination allows the occupational health and safety professional to see what tasks, environmental situations, and/or worker actions contribute to aerosol concentration and potential exposure. VEM can help identify factors responsible for temporal variations in concentration. VEM can assist with training, engage workers, convince managers about necessary remedial actions, and provide for continuous improvement of the workplace environment. Although using DRIs for control evaluation, ACM and VEM can be time-consuming, the resulting information can provide useful data to prompt needed action by employers and employees. Other barriers to adoption include privacy and security issues in some worksites. This review seeks to provide information so occupational health and safety professionals can better understand and effectively use these powerful applications of aerosol DRIs.

Video Exposure Monitoring and Position Tracking for Evaluating Particulate and Gas Exposures in a Fully Enclosed Small Arms Firing Range.

The exposure environment in small arms firing ranges is dynamic since ventilation conditions vary in space and time and instructors continuously move around throughout the range. Understanding the impact of engineering controls and instructor behavior on the levels of particulates and gases in the breathing zone is required for providing recommendations to mitigate exposure. In this study, video exposure monitoring (VEM) and position tracking technologies were used in conjunction with real-time measurements of ultrafine particle (UFP) and carbon monoxide (CO) exposures in the breathing zone of instructors in an enclosed small arms firing range. VEM was completed using Enhanced Video Analysis of Dust Exposure 2.1 developed by the National Institute for Occupational Safety and Health. With this program, video recordings of Combat Arms instructor activity were synced with exposure data collected in real-time during small arms training. Position tracking was completed using a system by Pozyx, which uses ultra-wideband (UWB) technology. Position tracking data was aligned with real-time sensor data via time-synchronization. VEM identified that the largest peaks in UFP and CO concentrations generally occurred when instructors were close to the firing line assisting shooters during live fire and when instructors were located near the center of the range near the back wall where the air supplies transition between the Left-Hand-Side (LHS) and Right-Hand-Side (RHS). The UWB position tracking results agreed with the VEM results, confirming that peak exposures occurred when firing range instructors were near the center of the range close to the back wall where the LHS and RHS air supplies transition. Without these exposure visualization technologies, this observation could not have been made. Thus, exposure visualization is a valuable tool to identify gaps in exposure assessment, although future technologies should focus on automation to expedite analysis.

Evaluation of the ceiling levels of ortho-phthalaldehyde exposure among health care workers engaged in endoscope disinfection: A new methodology using video-exposure monitoring.

ObjectivesThe present study aimed to develop a method for measuring the ceiling level of ortho‐phthalaldehyde (OPA) exposure and evaluate the ceiling levels of OPA exposure among health care workers who handle disinfectant solutions containing OPA for the disinfection of endoscopes.MethodsThe study consisted of a preliminary survey and main survey. In the preliminary survey, processes involving high‐concentration exposure to OPA were identified by video‐exposure monitoring (VEM). In the main survey, the ceiling levels of OPA exposure for high‐concentration exposure processes identified from the results of the preliminary survey were determined using a measuring method combining sampling using a 2,4‐dinitrophenylhydrazine‐silica cartridge and analysis by high‐performance liquid chromatography tandem mass spectrometry.ResultsIn the preliminary survey, seven processes involving high‐concentration exposure to OPA were identified by VEM. The duration of each process was short, lasting from 20 seconds to a few minutes. In the main survey, the OPA concentrations for the identified high‐concentration exposure processes ranged from 1.18 to 4.49 ppb, which markedly exceeded the threshold limit value ceiling (TLV‐C) of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists.ConclusionsThe method for measuring the ceiling level of OPA exposure was established using VEM and the highly sensitive method of chemical analysis; and we successfully evaluated the ceiling levels of OPA exposure among health care workers engaged in endoscope disinfection. This approach can also be applied to other chemical substances with recommended TLV‐Cs, and important information for reducing exposure can thus be obtained.

Helmet-CAM: Strategically Minimizing Exposures to Respirable Dust Through Video Exposure Monitoring.

Exposure to respirable crystalline silica (RCS) remains a serious health hazard to the US mining workforce who are potentially exposed as various ore bodies are drilled, blasted, hauled by truck, crushed, screened, and transported to their destinations. The current Mine Safety and Health Administration (MSHA) permissible exposure limit (PEL) for RCS remains at approximately 100 μg/m3, but it is noteworthy that the Occupational Safety and Health Administration (OSHA) has lowered its PEL to 50 μg/ m3 (with enforcement dates staggered through 2022 for various sectors), and the National Institute for Occupational Safety and Health (NIOSH) has held a 50 μg/m3 recommended standard since 1976. To examine a method for reducing RCS exposure using a NIOSH-developed video exposure monitoring (VEM) technology (referred to as Helmet-CAM), video and respirable dust concentration data were collected on eighty miners across seven unique mining sites. The data was then collated and partitioned using a thresholding scheme to determine exposures that were in excess of ten times the mean exposure for that worker. Focusing on these short duration, high magnitude exposures can provide insight to implement controls and interventions that can dramatically lower the employee's overall average exposure. In 19 of the 80 cases analyzed, it was found that exposure could be significantly lowered by 20% or more by reducing exposures that occur during just 10 min of work per 8-hour shift. This approach provides a method to quickly analyze and determine which activities are creating the greatest health concerns. In most cases, once identified, focused control technologies or behavioral modifications can be applied to those tasks.

Determinants of Airborne Solvent Exposure in the Collision Repair Industry.

To assess the determinants of airborne solvent exposures in contemporary vehicle collision repair workplaces. Personal, full-shift airborne solvent exposures (n = 97) were assessed in 85 vehicle collision repair workers from 18 workshops. Peak exposures were assessed using a small number of video exposure monitoring measurements. Solvent exposures were highest in spray painters (geometric mean = 2.7 ppm) followed by panel beaters (0.5 ppm), but were well below workplace exposure standards. The lowest exposure levels were observed for mixing room extraction located away from the mixing bench [exposure ratio (ER) = 0.51, 95% confidence interval (CI) = 0.30-0.87]. Time spent mixing paint was associated with higher exposures (ER for every 10-min increase = 1.14, 95% CI = 1.05-1.24), as was time spent cleaning equipment with solvents (ER = 1.11, 95% CI = 0.88-1.39), spraying primer (ER = 1.10, 95% CI = 0.96-1.27), and spraying clear coat paint (ER = 1.07, 95% CI = 1.00-1.15). Overall, the combined non-spray painting tasks (mixing paint, degreasing, and cleaning equipment) were more strongly associated with exposure (ER = 1.10, 95% CI = 1.03-1.18) than the combined spray painting tasks (ER = 1.03, 95% CI = 1.00-1.05). Peak exposures ranged from 10 to 1100 ppm with the strongest and most frequent peaks occurring during paint mixing, decanting of solvents, cleaning of equipment, and painting in a cross-draft spray booth. Airborne solvent exposures in the collision repair industry were associated with job title, the design and location of exhaust ventilation and emission sources, and time spent on specific tasks, with the highest average and peak exposures shown for non-spray painting tasks. These findings provide a contemporary basis for intervention programmes to reduce airborne solvent exposures in this industry.

Wood Dust in Joineries and Furniture Manufacturing: An Exposure Determinant and Intervention Study.

To assess wood dust exposures and determinants in joineries and furniture manufacturing and to evaluate the efficacy of specific interventions on dust emissions under laboratory conditions. Also, in a subsequent follow-up study in a small sample of joinery workshops, we aimed to develop, implement, and evaluate a cost-effective and practicable intervention to reduce dust exposures. Personal inhalable dust (n = 201) was measured in 99 workers from 10 joineries and 3 furniture-making factories. To assess exposure determinants, full-shift video exposure monitoring (VEM) was conducted in 19 workers and task-based VEM in 32 workers (in 7 joineries and 3 furniture factories). We assessed the efficacy of vacuum extraction on hand tools and the use of vacuum cleaners instead of sweeping and dry wiping under laboratory conditions. These measures were subsequently implemented in three joinery workshops with 'high' (>4 mg m-3) and one with 'low' (<2 mg m-3) baseline exposures. We also included two control workshops (one 'low' and one 'high' exposure workshop) in which no interventions were implemented. Exposures were measured 4 months prior and 4 months following the intervention. Average (geometric means) exposures in joinery and furniture making were 2.5 mg m-3 [geometric standard deviations (GSD) 2.5] and 0.6 mg m-3 (GSD 2.3), respectively. In joinery workers cleaning was associated with a 3.0-fold higher (P < 0.001) dust concentration compared to low exposure tasks (e.g. gluing), while the use of hand tools showed 3.0- to 11.0-fold higher (P < 0.001) exposures. In furniture makers, we found a 5.4-fold higher exposure (P < 0.001) with using a table/circular saw. Laboratory efficiency experiments showed a 10-fold decrease in exposure (P < 0.001) when using a vacuum cleaner. Vacuum extraction on hand tools combined with a downdraft table reduced exposures by 42.5% for routing (P < 0.1) and 85.5% for orbital sanding (P < 0.001). Following intervention measures in joineries, a borderline statistically significant (P < 0.10) reduction in exposure of 30% was found in workshops with 'high' baseline exposures, but no reduction was shown in the workshop with 'low' baseline exposures. Wood dust exposure is high in joinery workers and (to a lesser extent) furniture makers with frequent use of hand tools and cleaning being key drivers of exposure. Vacuum extraction on hand tools and alternative cleaning methods reduced workplace exposures substantially, but may be insufficient to achieve compliance with current occupational exposure limits.

Short-term Variation in Occupational Exposure to Air Contaminants

Many industrial workers are exposed to air contaminants. A significant proportion of this exposure is found to occur as short peaks, a fact that has received limited attention in the literature. The present study focuses on short-term variation in air contaminant exposure measured at the level of seconds, linking exposure peaks to typical work situations in selected Swedish industries. The video exposure monitoring method was used to characterize this variation. Ten different videos were analyzed, from recordings varying in length between 15 and 34 minutes. Cumulative exposure for sampling intervals ranked from high to low, relative to the total exposure was calculated as a function of time. Measures of exposure variation included geometric standard deviation and maximum exposure divided by arithmetic mean. The results show that the characteristics of the variation differ between industrial situations. Samples from the stone, wood, and pharmaceutical industries generated the highest variation, implying that exposure peaks of short duration explain a large proportion of the total exposure. It can be concluded that video monitoring of exposure, combined with calculation of exposure variation as percentage of time accounting for given percentages of exposure, can help to reduce exposure to air contaminants in industrial situations by introducing more targeted control measures.

Research Note: Video exposure monitoring for transfer of knowledge in chemical hazards to small enterprises

Despite the development of effective control technology, occupational exposure to silica and wood dust is a significant important problem for many small enterprises in wood working and quarrying industries. Tens of millions of workers’ occupations involve hazardous silica dust exposure and within the European Union alone, about 3.6 million workers are exposed to inhalable wood dust. The present study used the visualisation method PIMEX for transfer of knowledge in how health risks may be reduced. Typical work situations observed to cause high dust exposures were recorded. The results demonstrate that appropriate use of generally available technology and knowledge can significantly reduce worker exposure. The PIMEX-video monitoring method is a useful tool in knowledge transfer and also is seen to improve worker’s as well as manager’s motivation to use available knowledge. Case studies of the application of the technology have been made available on Internet. Visualised presentations using the PIMEX recordings are seen to be more effective compared to the more traditional training materials.

Video Exposure Monitoring as Part of a Strategy to Assess Exposure to Nanoparticles

There is a growing awareness of the potential risks for human health of exposure to ultrafine particles or nanoparticles. In that context, workplace air measurements become important, and various strategies have been developed to monitor exposure. In addition, observations and time/activity registrations are part of the exposure assessment strategy in many studies. Video exposure monitoring (VEM) can be of added value in these strategies. VEM combines exposure data with simultaneous video pictures of the process. The PIMEX method (Picture Mix Exposure) was used as the VEM studied. The possibility to combine PIMEX and measurement instruments for nanoparticles was the object of this study. The starting point was a review of available instruments for workplace air measurements of nanoparticles. Publications of strategies to assess exposure to nanoparticles were also studied to review whether observations were part of these strategies. Finally, a technical review of combining PIMEX and the compatible measurement instruments was undertaken and explored as part of the strategy to assess exposure to nanoparticles. A variety of instruments are used to measure nanoparticles. One category is (near) real-time monitoring instruments, which determine numbers and particle size distribution or surface area concentration. Other instruments require sample collection in order to characterize the nanoparticles chemically and physically by microscopic analyses and/or elemental analyses. Only some of these instruments are technically compatible with PIMEX. With the PIMEX2008 version 1.02 software, it is possible to synchronize up to four different measuring instruments simultaneously with the video recording. PIMEX as a VEM method can be a useful tool as part of the strategy to assess exposure to nanoparticles. It can also be of value for other purposes like training, education, and risk communication. The possibility to synchronize more than one measuring instrument can be useful to simultaneously monitor different targets in the workplace, e.g. worker exposure in the breathing zone and background concentration.

Visualisation of exposure to nanoparticles using PIMEX

In 2010 the Video Exposure Monitoring method PIMEX was applied to visualize exposure to nanoparticles for several tasks. Next to personal observations the video captured the working conditions and registered possible changes in operational conditions. Simultaneously and coupled with the video both the personal exposure (in the breathing zone) and the background exposure were monitored. In this way the personal exposure to synthetic particles can be corrected for the background exposure to natural occurring nanoparticles or confounding factors. The resulting videos can be edited and used for risk communication purposes. Overall, PIMEX can be of added value for the risk assessment of engineered nanoparticles.

Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals

Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

Field Evaluation of an Engineering Control for Respirable Crystalline Silica Exposures During Mortar Removal

During mortar removal with a right angle grinder, a building renovation process known as “tuck pointing,” worker exposures to respirable crystalline silica can be as high as 5 mg/m3, 100 times the recommended exposure limit developed by the National Institute for Occupational Safety and Health. To reduce the risk of silicosis among these workers, a vacuum cleaner can be used to exhaust 80 ft3/min (2.26 m3/min) from a hood mounted on the grinder. Field trials examined the ability of vacuum cleaners to maintain adequate exhaust ventilation rates and measure exposure outcomes when using this engineering control. These field trials involved task-based exposure measurement of respirable dust and crystalline silica exposures during mortar removal. These measurements were compared with published exposure data. Vacuum cleaner airflows were obtained by measuring and digitally logging vacuum cleaner static pressure at the inlet to the vacuum cleaner motor. Static pressures were converted to airflows based on experimentally determined fan curves. In two cases, video exposure monitoring was conducted to study the relationship between worker activities and dust exposure. Worker activities were video taped concurrent with aerosol photometer measurement of dust exposure and vacuum cleaner static pressure as a measure of airflow. During these field trials, respirable crystalline silica exposures for 22 samples had a geometric mean of 0.06 mg/m3 and a range of less than 0.01 to 0.86 mg/m3. For three other studies, respirable crystalline silica exposures during mortar removal have a geometric means of 1.1 to 0.35. Although this field study documented noticeably less exposure to crystalline silica, video exposure monitoring found that the local exhaust ventilation provided incomplete dust control due to low exhaust flow rates, certain work practices, and missing mortar. Vacuum cleaner airflow decrease had a range of 3 to 0.4 ft3/min (0.08 to 0.01 m3/sec2) over a range of vacuum cleaners, hose diameters, and hose lengths. To control worker exposure to respirable crystalline silica, local exhaust ventilation needs to be incorporated into a comprehensive silica control program that includes respiratory protection, worker training, and local exhaust ventilation.

Evaluation of Noise Attenuation and Verbal Communication Capabilities Using Three Ear Insert Hearing Protection Systems Among Airport Maintenance Personnel

The goal of this project was to determine whether one type of earplug would allow a user to hear communication in a noisy environment better than two other types of earplugs. The three types of earplugs studied are newly available on the market. Sonomax SonoCustoms are custom fitted to the user. E-A-R Push-Ins are the newest form of foam earplugs, and Howard Leight SmartFits have an adaptable shape. One of the earplug manufacturers claimed to have improved verbal communications due to the design of the earplug. We hypothesized that the type of earplug providing better communication properties would have lower attenuation around the communication frequencies compared with the other types. To test this hypothesis, we used speech intelligibility and attenuation tests in the laboratory on 26 subjects, and real-time video exposure monitoring in the field (airport maintenance personnel) for visual communication cues. ANCOVA was used to analyze the data from the laboratory study. The type of earplug worn was not significant in the model (p-value 0.0849), nor was attenuation of the earplug (p-value 0.2379). Further analysis showed that attenuation did not differ significantly among earplugs (p-value 0.5903). Logistic regression was used to analyze the data from the field study. Again, the type of earplug was not significant in the model (p-value 0.0965). A comfort questionnaire determined that Howard Leight SmartFits and the E-A-R Push-Ins were more comfortable and easier to use than the Sonomax HPDs (p-value <0.0001). We found a definite difference between manufacturers' attenuation data and our attenuation data, especially in the frequencies for 125–1000 Hz. Also, there was no difference in frequency and overall attenuation among the HPDs. This resulted in no difference in communication abilities among the types of HPDs.

Occupational Exposure Visualization Comes of Age

It has been 20 years since video exposure monitoring (VEM) was embraced as an instrument to provide better documentation of at-risk workers both in Europe and in the United States. Although the first VEM efforts started independently, the passion for this new technology and what it can do to improve the occupational environment has been advanced by a small but growing team of researchers on both sides of the Atlantic. As technology advances over the next ten years, VEM is set to become one of the major instruments in the arsenal of occupational exposure assessment and control. The technical aspects and uses of VEM are reviewed in this issue by some of the key players in these developments (Rosen et al., 2005). In the 1980s a small group of researchers from the engineering control technology branch of the National Institute for Occupational Safety and Health (NIOSH) were working on developing controls to reduce worker exposure to airborne chemicals during batch processing at a manufacturing plant in the Midwest. The research team consisted of a chemical engineer and two occupational hygienists, one specializing in the use of real-time instruments and the other in ergonomics. The diverse talents and skill sets of this team formed a synergy that took advantage of emerging technologies in the portable computer, video and realtime sensor markets (McGlothlin et al., 1987; 1996). The result of the application of this new technology, VEM in the United States was very promising. For the first time, researchers could discern exposure sources and the interaction between work practices and engineering controls such as local exhaust ventilation. Pinpointing exposure sources led to cost effective controls and the development of an effective feedback mechanism for showing workers and management where they had exposures and where they could be controlled. Overlaying videography with the real-time particulate sensors proved very effective. At the same time, unknown to the NIOSH researchers, a like-minded group of researchers at the National Board of Occupational Safety and Health in Sweden (now called the National Institute for Working Life) were considering ways to engage exposed workers in environmental control processes (Rosen and Lundstrom, 1987). The goal of this group was to develop methods for workers to see with their own eyes the potential hazards (in real-time) to which they were being exposed. Computer and video technology were getting less expensive and more portable, and real-time instruments (in the United States the instrument was the handheld aerosol monitor or HAM) were being used for particulate monitoring. By visualizing the work being done and combining it with real-time monitoring, occupational hygienists had a formula for success. They could provide a convenient means of feedback for workers and management and they had a new weapon to ‘see’ exposure sources and targeting controls. As the benefits of this new occupational exposure assessment method became obvious, other NIOSH researchers applied this method to their projects, resulting in a popular NIOSH government publication titled ‘Analyzing workplace exposure using direct reading instruments and video exposure monitoring techniques’, (CDC/NIOSH, 1992). Researchers for the National Institute for Working Life in Sweden identified two methodologies to evaluate worker exposure to air contaminants, one of which was commercialized (Walsh, 2002). From 1980 through the 1990s NIOSH researchers explored different ways to use this technology. They concluded that while the technology was unique, it would primarily be used to *Tel: +1 765 469 6359; fax: +1 765 496 1377; e-mail: jdm3@purdue.edu

A Review of Video Exposure Monitoring as an Occupational Hygiene Tool

This study reviews use of video exposure monitoring (VEM, also known as PIMEX) as an occupational hygiene tool since its inception in the mid-1980s. VEM involves the combination of real-time monitoring instruments, usually for gases/vapours and dust, with video of the worker's activities. VEM is an established method used by practitioners in different countries. The technical aspects of these VEM systems are described, then applications of VEM are discussed, focussing on task analysis, training (risk communication), encouraging worker participation in and motivation for improvements in the workplace environment and occupational hygiene research. The experiences from these applications are used to illustrate how exposure visualization with video can act as a catalyst, initiating a change process in the workplace. Finally, the role of VEM as a workplace improvement tool, now and in the future, is discussed.

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.

A control technology evaluation of state-of-the-art, perchloroethylene dry-cleaning machines.

NIOSH researchers evaluated the ability of fifth-generation dry-cleaning machines to control occupational exposure to perchloroethylene (PERC). Use of these machines is mandated in some countries; however, less than 1 percent of all U.S. shops have them. A study was conducted at a U.S. dry-cleaning shop where two fifth-generation machines were used. Both machines had a refrigerated condenser as a primary control and a carbon adsorber as a secondary control to recover PERC vapors during the dry cycle. These machines were designed to lower the PERC concentration in the cylinder at the end of the dry cycle to below 290 ppm. A single-beam infrared photometer continuously monitors the PERC concentration in the machine cylinder, and a door interlock prevents opening until the concentration is below 290 ppm. Personal breathing zone air samples were measured for the machine operator and presser. The operator had time-weighted average (TWA) PERC exposures that were less than 2 ppm. Highest exposures occurred during loading and unloading the machine and when performing routine machine maintenance. All presser samples were below the limit of detection. Real-time video exposure monitoring showed that the operator had peak exposures near 160 ppm during loading and unloading the machine (below the OSHA maximum of 300 ppm). This exposure (160 ppm) is an order of magnitude lower than exposures with more traditional machines that are widely used in the United States. The evaluated machines were very effective at reducing TWA PERC exposures as well as peak exposures that occur during machine loading and unloading. State-of-the-art dry-cleaning machines equipped with refrigerated condensers, carbon adsorbers, drum monitors, and door interlocks can provide substantially better protection than more traditional machines that are widely used in the United States.

Computer-aided video exposure monitoring.

A computer-aided video exposure monitoring system was used to record exposure information. The system comprised a handheld camcorder, portable video cassette recorder, radio-telemetry transmitter/receiver, and handheld or notebook computers for remote data logging, photoionization gas/vapor detectors (PIDs), and a personal aerosol monitor. The following workplaces were surveyed using the system: dry cleaning establishments--monitoring tetrachoroethylene in the air and in breath; printing works--monitoring white spirit type solvent; tire manufacturing factory--monitoring rubber fume; and a slate quarry--monitoring respirable dust and quartz. The system based on the handheld computer, in particular, simplified the data acquisition process compared with earlier systems in use by our laboratory. The equipment is more compact and easier to operate, and allows more accurate calibration of the instrument reading on the video image. Although a variety of data display formats are possible, the best format for videos intended for educational and training purposes was the review-preview chart superimposed on the video image of the work process. Recommendations for reducing exposure by engineering or by modifying work practice were possible through use of the video exposure system in the dry cleaning and tire manufacturing applications. The slate quarry work illustrated how the technique can be used to test ventilation configurations quickly to see their effect on the worker's personal exposure.

Video Exposure Monitoring—A Means of Studying Sources of Occupational Air Contaminant Exposure, Part I—Video Exposure Monitoring Techniques

Abstract Conventional sampling with pumps and sampling media can be used to determine whether exposures to air contaminants are excessive. Unfortunately, such results provide few insights into the reasons for the excessive exposures. However, Video Exposure Monitoring can be used to identify the sources causing these excessive exposures. Any movable instrument that has an analog or digital output can potentially be used for Video Exposure Monitoring. The instrument should be light enough to mount on a worker, be specific for the chemical interest, and have a short time constant. Although most existing direct-reading instruments do not simultaneously meet all these requirements, currently available instruments, such as aerosol photometers, photoionization detectors, and portable infrared analyzers have been used effectively. The analog or digital output from direct-reading instruments can be recorded by data-logging devices. The data-logging devices transfer the exposure data to a personal computer for sto...