S. Liu, K. Hammond, University of California, Berkeley, CA.
In 2000, a respiratory health survey conducted in an automobile assembly plant found that workers from a body weld department had an elevated rate of self-reported respiratory symptoms compared to painters and assembly workers. Consequently, the ventilation system was improved. The effectiveness of the changes was evaluated by mapping of particulate matter (PM) in the body weld department. Temporal variation was monitored with stationary sampling at several fixed locations. Spatial variation was evaluated with 1-min time-weighted average PM concentrations measured at 212 locations throughout the process area. The sampling was repeated on six different days during two shifts. Concentrations at workstations were compared to those at grid points. Statistical methods were used to assess the variability in concentration. PM10 concentration as measured by DustTrak at a fixed location during operation varied from 0.10 mg/m3 to 1.38 mg/m3, with a mean of 0.76 mg/m3 and a standard deviation of 0.31 mg/m3. The mean concentration over the entire process area (212 points) varied from 0.31 mg/m3 to 0.50 mg/m3 as measured by Casella. Maps of mass concentration by location revealed several potential high-concentration areas. Maps for particle in different sizes (respirable, PM10, PM2.5) as well as particle count indicated similar hot-spot patterns. PM concentrations at some welding workstations tend to be higher than those at grid points. Although PM concentrations were below occupational standards, they were much higher than environmental standards. Temporal variation was significant at a given location, partly due to operation conditions. Mean concentration over the process area significantly differed from day to day; however, it did not differ significantly from day shift to evening shift. Mapping was shown to be an effective method to identify potential hot spots; a well-designed sampling protocol is necessary to capture the variability during mapping.
S. Weichenthal, A. Dufresne, C. Infante-Rivard, McGill University, Montréal, QC, Canada.
A sampling campaign was conducted in Montréal, Québec, to explore determinants of ultrafine particle (UFP) exposures in transportation microenvironments. Three days a week for four months, UFP (0.2-1μm) exposure data was collected by one researcher during a commute including a walk (0.5 km), a bus ride (5 km), and an automobile ride (26 km) in each direction using a TSI P-TRAK. On each sampling day, temperature, humidity, and wind speed data were collected, and the positions of bus and automobile windows were recorded. In total, exposure information was obtained for 54 commutes between May and September 2006. Average morning exposures were 20 657cm-3 (95% confidence interval [CI]: 17 189, 23 525) for the walk; 26 642 cm-3 (95% CI: 23 625, 29 659) for the bus ride; and 35 104 cm-3 (95% CI: 31 444, 38 764) for the automobile ride. Evening exposures were slightly lower than in the morning, but the same general pattern was observed. In multivariable models, only temperature and wind speed were significant determinants of UFP exposures in all three microenvironments, with each 5oC increase in temperature corresponding to decreases of 5920 cm-3 (95% CI: -8270, -3570) for the morning walk; 5440 cm-3 (95% CI: -8500, -2380) for the bus ride; and 7350 cm-3 (95% CI: -10450, -4250) for the automobile ride. Similarly, each 10 km/h increase in wind speed was associated with decreases of 5950 cm-3 (95% CI: -8860, -3030) for the morning walk; 6080 cm-3 (95% CI: -9000, -3160) for the bus ride; and 5630 cm-3 (95% CI:-9490, -1770) for the automobile ride. Humidity was a significant determinant of morning UFP exposures in buses only (β=-208 cm-3%, 95% CI: -417, -0.17), but in general similar patterns were observed for the evening hours. Our findings suggest that UFP exposures in transportation microenvironments depend on the type of transportation as well as meteorological conditions.
V. Hillman, Liberty Mutual Group, Hopkinton, MA.
Engineering control of silica exposures remain a challenge for industrial hygienists in a number of industries. The recent reduction of the threshold limit value has modified the exposure status of some workers who previously were considered to have a controlled exposure. The use of local exhaust ventilation (LEV) and wet methods to control silica (quartz and cristobalite) exposures while finishing granite in the monument and architectural product industries are explored in this paper. Information on personal sample results compared to various occupational exposure limits while using these two types of engineering controls are outlined in this presentation, as are related LEV system performance measures.
G. Marchand, C. Pépin, Y. Beaudet, IRSST, Montréal, QC, Canada; S. Villeneuve, G. Boivin, Préventex, Longueuil, QC, Canada; M. Lalonde, HDS Environnement, Montréal, QC, Canada.
Cotton workers are recognized as being a group at risk of developing occupational lung diseases. However, the agent responsible for this respiratory condition remains unknown. Some researchers have identified endotoxins as being a potential etiologic agent for some respiratory problems found in cotton industry workers. The aims of this study were to document the concentration of endotoxins found in the ambient air, to identify the processing steps with the highest endotoxin concentrations, and to identify the ones that exceed the proposed relative limit value. The relationship between the endotoxin concentrations found in the air, the one measured in the water of the air cleaning devices, and in the material manipulated at each step was also evaluated. The four mills studied process cotton fibers. In each mill, all of these endotoxin concentrations were evaluated on three different occasions. All the samples were analyzed using the chromogenic limulus amebocyte lysate (LAL) method, using a kinetic detection principle based on the Institut de Recherche Robert Sauvé en Santé et Sécurité au Travail’s standard method. A large variability in the concentrations of endotoxins in the air was observed, depending on the mill, the processing step, and the time of the year. Despite these variations, some processing steps were identified as being major generators of endotoxins in the ambient air. A relation was established between concentrations of endotoxins in the ambient air, the water in the air cleaning devices, and the material manipulated.
L. McKernan, K. Wallingford, M. Hein, NIOSH, Cincinnati, OH; H. Burge, R. Herrick, Harvard University, MA; C. Rogers, University of Massachusetts Amherst, Amherst, MA.
Although exposure to bacteria has been assessed in cabin air previously, minimal numbers of samples have been collected in flight. The purpose of this research was to comprehensively characterize bacterial concentrations in the aircraft cabin. Twelve randomly selected flights were sampled on Boeing 767 aircraft, each with a flight duration between 4.5 and 6.5 hr. N-6 impactors were used to collect sequential, triplicate air samples in the front and rear of coach class during six sampling intervals throughout each flight: boarding, midclimb, early cruise, midcruise, late cruise, and deplaning. Comparison air samples were also collected inside and outside the airport terminals at the origin and destination cities. The MIXED procedure in SAS was used to model the mean and the covariance matrix of the natural log transformed bacterial concentrations. A total of 513 airborne culturable bacterial samples was collected. During flight (midclimb and cruise intervals), a model adjusted geometric mean (GM) of 136 total colony forming units per cubic meter of air sampled (CFU/m3) and geometric standard deviation of 2.1 was observed. Bacterial concentrations were highest during the boarding (GM 290 CFU/m3) and deplaning (GM 549 CFU/m3) processes. In the modeled results, total bacterial concentrations observed during flight were significantly lower than GMs for boarding and deplaning (p-values <0.0001-0.021). The analysis of specific genera indicates that passenger activity and high occupant density contribute to airborne bacterial generation. The bacteria recovered on the observed flights were either common skin surface organisms (primarily Gram-positive cocci), or were organisms common in dust and in outdoor air.
Y. Kubota, K. Kimura, KOKEN-LTD, Hanno, Saitama, Japan; Y. Fujishiro, K. Kamifukumoto, T. Iwasaki, KOKEN-LTD, Tokyo, Japan; N. Imanishi, K. Nakajima, S. Aiso, K. Omae, Keio University, Tokyo, Japan; S. Tanaka, Jumonji University, Saitama, Japan; H. Miyauchi, The Association of Industrial Health, Tokyo, Japan.
The Ministry of Health, Labour and Welfare of Japan formulated a guideline to maintain formaldehyde level of special-purpose work areas that use formaldehyde to 0.25 ppm or lower. Students carry a high risk of exposure to highly concentrated formaldehyde in dissection laboratories of medical schools. In this study, we surveyed the actual condition of dissection laboratories in several schools. As a result, average formaldehyde level in dissection laboratories was found to be 0.35-1.7 ppm in all schools, even when the general ventilation system was on. This level was significantly higher than the guideline level stipulated by the ministry. There were about 20 dissection tables in the dissection rooms. Each table was emitting significantly high levels of formaldehyde. In fact, formaldehyde levels near donor bodies reached 5 ppm or exceeded 10 ppm in some cases. Therefore, we believe that a general ventilation system is not an adequately effective measure. Given this factor, we developed a horizontal-flowing, push-pull ventilation system. As a result, we succeeded in lowering the formaldehyde level and exposure level. We conducted a computational fluid dynamics (CFD) analysis and an airflow visualization experiment and determined the optimum airflow rate for each system. We installed a high-performance activated charcoal filter intended for formaldehyde prevention to each pull-hood in order to enable indoor ventilation. This eliminated the need to install ducts. Instead, this push-pull ventilation system can be easily installed on dissection tables. As the next step, we measured formaldehyde level in actual dissection laboratories in order to evaluate the effectiveness of this push-pull ventilation system. As a result, formaldehyde level of the laboratories and respiration area (1200 mm from the floor) exceeded the guideline level when the ventilation system was off; however, it was sufficiently below the guideline level when the ventilation system was on.
C. Porter, Air Science & Engineering, LLC, Dayville, CT.
Industrial hygiene and safety professionals know that propeller fans can significantly disrupt the capture efficiency of an exhaust hood. Despite this knowledge, propeller fans directed at exhaust hoods are still commonly seen in many work settings. High exposure levels were detected during a thermal cutting operation. Computational fluid dynamics (CFD) analysis is used to demonstrate the significant impact the propeller fan has on hood performance and the improvements possible if the fan is eliminated or replaced with a dedicated supply system. The analysis was validated using exposure monitoring data. The CFD output, in the form of easily understandable graphic images, may be helpful to educate operators, supervisors, facility engineers, and managers about propeller fans so that work practices and process setups will be modified. Significant reductions in exposure levels are possible.
J. Glancey, M. Griffith, D. Brisach, J. Nasr, J. Konchar, University of Delaware, Newark, DE; P. Popper, Peacock Sales Inc., Wilmington, DE.
The use of hand-struck and power tools is an integral part of many industries throughout the world, and many jobs require frequent and often continuous use of these devices. Injuries in the workplace resulting from these tools have been examined extensively. Several studies have demonstrated a link between the long-term effects of vibration exposure and permanent, irreversible damage to blood vessels and nerves in the hand and arm. Unless daily exposure to vibration is limited, ailments including hand-arm vibration (HAV) syndrome, Raynaud’s phenomenon, and vibration white finger can develop. These injuries have been estimated to be prevalent in several industries; they pose a growing concern to the long-term health of workers worldwide. In light of the problems associated with the use of vibrating tools, a study was initiated to evaluate the performance of current tool designs and develop improved designs that mitigate some of the detrimental effects associated with their long-term use. The initial focus of the work was to improve hand-struck and power chisel designs by integrating reinforced engineering polymers between impacting metal components. To evaluate the effects of polymer-metal impact mechanisms on performance, experiments were conducted with several users in which this new design was compared to conventional tools. Results show that with the appropriate choice of polymer and reinforcement material, vibration emission can be significantly reduced; the corresponding change in cutting (output) force is relatively small and statistically insignificant. The effects of grip force on vibration transmission in the arm was also studied and found to vary among users. In general, it has been observed that vibration energy transmitted to the elbow was reduced with the use of polymer impact components and a smaller (looser) grip force.
R. Hall, G. Earnest, A. Garcia, R. McCleery, NIOSH, Cincinnati, OH.
Researchers from NIOSH evaluated carbon monoxide (CO) emissions and controls from gasoline-powered generators. This evaluation was part of a series of studies conducted by NIOSH investigators during the past several years to identify and recommend effective engineering controls to reduce the CO hazard and prevent CO poisonings in the boating industry. The performance of two (14-kW and 20-kW) Westerbeke Safe-CO generators were tested after being used on rental houseboats for a boating season. Each of the evaluated generators had between 1000 and 3000 hours of use and was equipped with catalytic converters and electronic fuel injection systems. Both old and new catalysts were evaluated. One houseboat containing a 14-kW generator was modified so testing could be accomplished using a side or stack exhaust configuration. The performance of the generators used for a season of boating was impressive. Average CO concentrations were generally below 5 ppm. Peak CO concentrations were all well below 20 ppm. The new catalysts seemed to perform slightly better than the ones used for the season. CO concentrations were slightly lower under no-electrical-load conditions as compared to loaded. CO concentrations measured directly in the exhaust stack were approximately 200 ppm for the fully warmed generator. That compares to CO concentrations NIOSH researchers measured that exceeded 10,000 ppm on older Westerbeke generators without the Safe-CO control systems. When comparing side vs. stack exhaust, the lower stern deck in the side exhaust configuration resulted in slightly higher concentrations. Use of the vertical exhaust stack with the Safe-CO generator is recommended to ensure redundancy in the system.
J. Glancey, D. Brisach, M. Griffith, J. Konchar, University of Delaware, Newark, DE; P. Popper, Peacock Sales Inc., Wilmington, DE.
Exposure to high noise levels may be the most common occupational hazard. Recent estimates suggest that as many as 30 million Americans are exposed to noise levels greater than the current safe limits for workplaces. At current durations of exposure, it is expected that 25% of these workers will develop permanent, noise-induced hearing loss. To address the adverse effects associated with the use of high-noise emission impact tools, a study was initiated to develop and evaluate alternate tool designs that reduce the potential for hearing loss. Recent work has focused on integrating advanced engineering polymers (composites) into tool designs to eliminate direct metal-to-metal impact. This approach has several significant performance advantages, including reduced operator discomfort due to hand-arm mechanical shock and reduced noise as well as less danger from flying metal fragments. To quantify sound emission characteristics of these new designs, continuous sound pressure, maximum sound pressure, and maximum sound pressure level were measured using an array of five precision microphones, each located 1 m from the tool. Data was sampled at 40 kHz while test subjects operated both pneumatic tools and hand-struck tools. Frequency spectra of the sound pressure signals were examined for all tool treatments; they indicate that the addition of a polymer insert between metal impact components significantly reduces noise emission, especially at higher frequencies. Sound pressure levels were reduced by as much as 4 dBA compared to conventional tool designs. As a result, tools that integrate polymer-based components may be operated for longer daily exposure times without inducing hearing loss. Data from this study may also help auditory and ergonomic specialists in understanding impulse noise characteristics and exposure.
L. Cannon, L. Xu, T. Hemenway, EnviroMed Services Inc., Meriden, CT.
The art and kiln rooms in 20 schools in 3 different districts in the state of Connecticut were assessed for lead risk in surface dust due to the past and present use of ceramic glazes. These glazes were found to contain lead and other heavy metals based on a review of the material safety data sheets (MSDSs) for ceramic glazes and associated products used in these art programs. The schools assessed included 4 high schools, 3 middle schools, and 13 elementary schools. The surfaces assessed included everyday contact surfaces and non-everyday contact surfaces in classrooms, art supply storage rooms, kiln rooms, and art teachers’ offices. The lead wipe sample results were compared to the most stringent lead standards of the State of Connecticut Department of Public Health, the U.S. Department of Housing and Urban Development, and the Environmental Protection Agency. Those lead standards are used in child-occupied facilities for children under six years of age to assess the risk for a lead hazard. It was found that all kilns and kiln rooms and more than 80% of art classrooms had surfaces contaminated with lead containing dust. A series of site-specific lead dust cleanup specifications were developed, and certified lead dust cleaning contractors were selected through a bidding process to conduct cleanup during school vacation and off-school hours. Monitoring of the cleanup projects included post-cleanup visual inspection and reoccupancy clearance testing to verify the project completion. MSDSs of different types of ceramic glazes were studied. Lead containing ceramic glaze will be eliminated from all art programs in schools grades K-12 to minimize lead hazard in schools. All schools are recommended to update their hazard communication program in compliance with OSHA regulations, giving special attention to establishing a current inventory of chemicals and products with updated MSDSs.
S. Milz, University of Toledo, Toledo, OH; A. Ames, M. Witherspoon, Delta Environmental Inc., Perrysburg, OH.
In the United States in 2004, over 670,000 regulated underground storage tanks were estimated to have been in use. The Bureau of Underground Storage Tank Regulation lists 24,352 active registered tanks in Ohio, with over 28,000 releases. Gasoline releases from these underground storage tanks result in petroleum constituents contaminating soil and groundwater. Volatile chemicals released into the soils may then be transported through vapor intrusion into buildings where workers are present, potentially exposing the workers to harmful chemicals. A study was performed evaluating the level of contaminants indoors at three operating establishments with subsurface gasoline contamination. The volatile petroleum constituents of interest were benzene, toluene, ethyl benzene, and xylenes (BTEX). Air sampling was conducted over a 24-hr period both inside and outside these three establishments. The majority of the measured air concentrations were less than the limit of detection for the analytical method, except for the toluene concentrations inside site 1. Using the detectable concentrations and the limit of detection for the analytical methods, a comparison was made to the vapor intrusion models from the Environmental Protection Agency and the Ohio State Fire Marshal. The air sampling results indicated that the levels within the buildings were well below regulatory limits for worker exposures. However, the vapor intrusion models indicated that subsurface contaminant levels posed a potential exposure to building occupants from soil and groundwater contamination. Future studies are planned to further evaluate this finding.
A. Scott, J. Wagner, S. Hatt, A. VanDyke, M. Goldberg, The Children’s Hospital of Philadelphia, Philadelphia, PA.
Heavy construction activities have the potential to produce respirable particles that may contain hazardous or nuisance dusts and/or fungal spores. To ensure the health and safety of our staff and patient population, we aimed to develop comprehensive, effective and practical measures to evaluate the effectiveness of construction control methods. In 2000, The Children’s Hospital of Philadelphia began a multiphased renovation of its inpatient facilities, including the addition of over 600,000 s.f. and a removal of the existing hospital facade and replacement with a clear glass enclosure. A preconstruction risk assessment was used to identify construction activities that were directly adjacent to occupied areas, some of which housed critical care patients. A variety of physical barriers and negative pressure controls was used to reduce airborne particulate levels in occupied areas. Visual inspections and air monitoring were used to measure the effectiveness of these controls. Weekly visual inspections of construction barriers included security, housekeeping, negative pressure, and the presence of penetrations. Quantitative air monitoring was conducted using a TSI DustTrak Aerosol Monitor 8520, providing real-time respirable particulate concentrations. Baseline samples were collected in the occupied areas prior to the start of construction. Once construction commenced, samples were again collected in the occupied area as well as in the construction space. If visual inspections or air monitoring results showed a significant increase above baseline conditions, immediate interventions were made to identify potential construction barrier breaches. Our program has allowed for a real-time data evaluation of the effectiveness of construction barriers, helping to ensure the maintenance of a safe and healthy environment for our staff and patients.
C. Harvey, Johns Hopkins University, Baltimore, MD.
This research was performed to evaluate the hypothesis that indoor concentrations of particulate matter (PM) from entrained helicopter exhaust negatively impact the respiratory health of exposed workers in an urban hospital complex. Questionnaires were developed and electronically delivered to approximately 1300 faculty and staff of an urban research hospital to assess their current respiratory health and manifestations of symptoms commonly associated with poor indoor air quality (IAQ). Surveys were collected and analyzed using multivariate statistical approaches, which positively identified an association between the presence of helicopter exhaust and the manifestation of IAQ symptoms. To further verify this finding, air samples were taken to measure levels of PM in the office atmosphere. These results show statistically significant increases in background PM levels on floors where a high number of study participants indicated having IAQ symptoms. A simulation model was also developed and verified by air sampling data. The simulation model, which was used to evaluate the dispersion of gas and particulate contaminants generated by helicopter emissions to floors where air samples were unattainable, demonstrated increased levels in areas served by air intakes above the helipad. Samples taken at the air intake for the ventilation system and on the 12th floor both demonstrate increases across all size fractions in PM concentration when the helicopter is present on the helipad. The simulation model also demonstrates a wide dispersion of contaminants to other floors due to the presence helicopter emissions on the helipad. Survey results associate well with air sampling data, with participants having higher prevalence of respiratory symptoms in areas with increased PM concentrations.
S. Thiagarajan, K. Ramanathan, H. Burge, D. Gallup, Environmental Microbiology Lab Inc., San Bruno, CA.
Mold present on indoor surface environments can be analyzed either by a viable methodology (quantitative fungal culture using swabs, dust samples, or bulk samples) or by a nonviable methodology (direct microscopic examination using tape lift, swab, dust samples, or bulk samples). In this paper, we compare these two methods using data analyzed over a period of two years (~73,000 nonviable and ~9,000 viable samples). Viable analyses were performed using three different culture media (malt-extract agar [MEA], dichloran glycerol [DG 18] agar, and cellulose). Nonviable analyses were performed by directly mounting the sample on a microscope after staining with lacto-cotton blue on a glass slide. A total of 228 different fungal types was reported using viable analysis, compared to 178 by nonviable analysis. The fungal type with the highest reported frequency using a viable culture analysis was Penicillium species (21%) followed by Cladosporium (18%), yeast (18%), Aspergillus niger (5%), Aspergillus versicolor (4%), and Stachybotrys (4%). In contrast the nonviable analysis reported Cladosporium species with the highest frequency (19%), followed by Stachybotrys (12%), Penicillium/Aspergillus-type spores (10%), Aspergillus (9%), Penicillium (6%), and Cheatomium species (6%). Overall it was observed that Cladosporium, Penicillium, and Aspergillus were the most common fungal types detected indoors. Penicillium was more often detected indoor when compared to Aspergillus. Stachybotrys was more often detected using nonviable analysis (12%) when compared to viable analysis (4%). Using cellulose media improved the chances of detecting Stachybotrys (16%), compared to MEA (4%). As expected, yeast was more often detected using viable analysis (18%) compared to nonviable analysis (0.54%). Similarly nonviable analysis exclusively reported organisms like Ceratocystis/Ophiostoma that are otherwise hard to culture. Overall, this study indicated that the analysis of the surface sample simultaneously using both these methods gave a better and broader spectrum of results that would otherwise have been missed by any single one of these methods.
T. Dubey, MACS Lab Inc., Santa Clara, CA.
Fungal succession and rate of competition among predominating fungal genera was studied on household substrates such as carpet and wood for a period of six months. Small mesh bags were filled with three sterilized pieces of carpet (1 cm2 in size) in four sets: one for initial examination, one for the first month, one for two months, and one for a six-month period of incubation, from March-August 2006. Similar sets were prepared for three 1-cm2 sterilized wood chips in each mesh bag. These bags were placed in a plastic chamber out of doors to see the process of colonization by naturally occurring fungal mycota. One bag of carpet pieces and one bag of wood chips were taken out for initial same-day examination after 6 hrs of exposure to the natural environment; three pieces were examined from each bag as three replicates. Each sample was washed with sterile distilled water to collect all fungal spores for direct microscopic examination. The remainder of the carpet pieces and wood chips were incubated on potato dextrose agar (PDA) plates for 7-10 days at 26ºC to isolate the fungal colonies growing on these substrates. The same procedure was followed for one, two, and six months of incubation treatments. Fifteen fungal mycota were observed from carpet and wood chips, and a gradual increase in fungal diversity with the increase in incubation time was observed. Predominating genera were Acremonium, Alternaria, Aspergillus spp., Aureobasidium, Chaetomium, Cladosporium, Graphium, Mucor, Penicillium, Phoma, Sporotrichum, Trichderma, and Ulocladium. Carpet was colonized rapidly and by higher number of fungal genera than wood chips. Wood chips were predominated by Graphium-like genera. Further analysis on fungal behavior on these surfaces will be discussed.