J. McKernan, CDC/NIOSH, Cincinnati, OH.
Our understanding of heat transfer and meteorological theory, and their applications for engineering control design, have evolved since Hemeon first published his research on heated process control in 1955. These refined theories were reviewed to develop a newly proposed equation to estimate buoyant plume volumetric flow. To determine which equations were most accurate, the proposed, ACGIH, and Hemeon’s equations were compared to direct measurements of buoyant flow parameters from laboratory experiments. Two hundred laboratory data points were collected at various excess temperature and height combinations using a hot-wire anemometer and a model exothermic process. The comparison of the three equations to experimental results was conducted by using multiple one sample T-tests for differences between the experimental data and solutions to each of the three equations. Statistical comparisons (difference of means, standard deviation and p values) of the volumetric flow from the experimental results and solutions from the three equations indicated that the ACGIH equation provided results that slightly overestimated the laboratory volumetric flow (ACGIH: 0.02, 0.30, 0.65). The proposed equation slightly underestimated the laboratory volumetric flow; however, it provided better overall results than Hemeon’s equation. Examining the p values, it can be seen that the proposed and the Hemeon equations provided results that were different from the experimental data (proposed: -0.06, 0.16, 0.03; Hemeon: 0.13, 0.35, 0.02). Overall, the proposed equation provides a slight underestimation of volumetric flow; however, this estimate has considerably less variability than either of the currently accepted equations. Benefits of the proposed equation are its ease of application, basis in well-developed heat transfer and meteorological theories, and lack of subjective safety factors that are built into the other currently accepted equations.
S. Shepherd, University of Massachusetts-Lowell, Lowell, MA.
Silica exposures in construction remain a top priority due to the serious consequences of exposure and the large and increasing volume of concrete construction. Environmental and occupational health professionals are seeking control solutions to this problem beyond the respiratory protection worn by workers. Contractors are also seeking to reduce the expense of clean up and the public image of a very dusty workplace. More contractors are willing to try local exhaust ventilation systems on concrete-cutting tools and, therefore, the need to understand these systems from a design standpoint is more important than ever. The LEV systems evaluated in this study consisted of two different portable vacuum cleaners and three different off-the-shelf cowls that may be attached to hammer drills and chippers. Field evaluations were held under controlled conditions at the New England Laborers Training Center. During concrete drilling, these systems reduced exposure to respirable concrete dust by an average of 85%. A minimum flow of 18 cfm was found to remove concrete dust to acceptable levels. Flow was measured by using a pitot tube and digital manometer in the field during the trials. Four different tools were evaluated ranging from a 7/8-inch SDS-plus rotary hammer to a 3/4-inch hex demo hammer as well as a pneumatic chipping gun. Consistent reductions were not achieved for chipping, but results indicate that with modifications, dust reduction is possible. Lab experiments were performed measuring velocity and static pressure in various configurations. Thus, the friction losses in typical corrugated hoses (f = 0.03) and entry losses through various cowls were calculated. Using this information, industrial hygienists working in construction can make design recommendations for the optimal portable dust removal systems for their application.
L. Menard, CSST, Montreal, PQ, Canada.
Wood dust fires and explosions caused injuries and fatalities among workers
involved in Quebec province woodworking facilities. Following those incidents,
the Prevention Inspection Department of the Quebec Health and Safety Commission
decided to initiate a wide inspection intervention program among all facilities
involved in woodworking processes. Different tools were developed for our
inspector formation taking the form of an inspection worksheet referring to main
rules of NFPA standard: NFPA 664 Standard for the Prevention of Fire and
Explosion in Wood Processing and Woodworking Facilities. A technical guide was
also developed for dust collecting and dust treatment equipment designers and
suppliers. The formation program was dispensed to 120 inspectors, and
information meetings were organized for more than 60 equipment suppliers and
designers. Inspection interventions took place in 143 different facilities and
necessitated 268 visits. Noncompliance was associated with absence or deficiency
in design and installation of deflagration venting in 73% of cases, absence of
positive shut off trap on dirty air stream in 65% of cases, and front flame
diverter on recirculated clean air stream in 69% of cases. Other safety devices,
such as rotary valve on dust collector waste outlet to stop deflagration
progression to bin or silo and spark detection and suppression system necessary
to protect dust recovery systems when abrasive cutting belt or other
high-incidence spark generating machines are used, were absent in a proportion
of 53% of cases.
Correctives measures required by our inspectors have been applied in more than
75% of interventions, and we expect to visit all our facilities within a 5-year
period. Those interventions necessitate a wide mobilization of our inspection
resources, but we remaine convinced that it will have a positive impact.
E. Stevenson, Liberty Mutual Industrial Hygiene Group, Hopkinton, MA.
Sound generated in the industrial environment is a concern for original equipment manufacturers and end users. Any time machinery is moved within a facility or new machinery is added, the contribution of the sound generated by that machine adds to the already existing overall noise levels in the plant. It’s important to be able to predict what the new noise level will be in order to know what measures might be necessary to take, should the overall noise level exceed the recommended thresholds—whether they are company design guides or occupational exposure limits. This presentation will introduce a new, still under development, technical report by the ANSI B11 Machine Tool Safety Standards Accredited Standards Committee (ASC). ANSI B11-TR5 was commissioned in 2003 by the B11 ASC. It will be a document written for the manufacturers and end users of industrial equipment. This presentation will provide a summary of the information and recommendations for the measurement and record keeping prescribed in this technical report. This ANSI Technical Report on Sound Level Measurement Guidelines was developed to provide useful and practical guidance to the suppliers and users of machines to accurately assess the sound level(s) generated by machines or machine production systems. Publication of the ANSI TR5 document becomes registered as a Technical Report by the American National Standards Institute. The document is not an American National Standard and the material contained in it is informative, not normative in nature.
P. Sampara, D. Chung, Workplace Safety and Insurance Board, Toronto, ON, Canada.
The purpose of this presentation is to describe a method of assessing vibration exposures for the compensation of work-related hand-arm vibration syndrome (HAVS) claims. Injuries or disease from occupational exposure to hand-arm vibration (HAV) is compensable in the province of Ontario under the Workplace Safety and Insurance Act that is administered by the Workplace Safety and Insurance Board (WSIB). The current WSIB policy for HAV requires two years of continuous exposure to high-frequency, rapid-acceleration vibratory tools. An assessment of the worker’s exposure to HAV is often needed to help adjudicators make a decision to either accept or deny claims for HAVS-related disorders. Until recently, HAVs exposure assessments for WSIB claims used vibration data previously gathered by the Ontario Ministry of Labor (MOL) for various tools and equipment. The vibration levels and duration of exposure were compared with the current ACGIH Threshold Limit Values (TLVs) for HAV. As a result of recent developments, such as adoption by some European Union (EU) countries of the EU Directive on Vibration, limitations of the MOL vibration data and the ACGIH TLVs, a new approach to vibration exposure assessment was developed. The new approach incorporates a comprehensive work history that includes the types of vibratory tools or equipment, frequency and duration of use, and factors that may influence vibration exposure. Vibration levels are estimated from sources such as the Centralized European Hand-Arm Vibration Database. Vibration exposure is calculated using the Hand-Arm Vibration Exposure Calculator, developed by the Health and Safety Executive in the United Kingdon, and the results are compared with the EU Directive on Hand-Arm Vibration. A vibration exposure ranking system is used to aid the lay adjudicators. A case example of a hand-arm exposure assessment is described to illustrate this new approach.
T. Morris, Ohio BWC, Employer Management Services (EMS), Cincinnati, OH.
EMS received a company request to do an initial assessment of employees’ exposures while milling the APIs oxycodone hydrochloride (OCH) and ibuprofen (IB). OCH is a centrally acting opioid analgesic approved by the U.S. FDA for moderate to severe pain management. IB is an approved nonsteroidal anti-inflammatory drug with analgesic and antipyretic properties. Many mistake FDA approval as a “blanket” safety approval. The approval is for the finished product and does not include exposure to the raw materials that can occur during manufacture. OCH can produce CNS effects, respiratory tract irritation, lung edema, and dizziness. IB can produce skin, eye, and respiratory tract irritation. Inhalation, skin or eye contact with either can result in sensitization. Personal samples were taken on the two workers milling the APIs. Task-based samples were taken because of the way the materials are handled. Exposures for the 6.5-minute milling and addition of 2.6 kg of OCH were 300 and 2,100 µg/m3. These are four and 28 times the 75 µg/m3 STEL; the 2,100 µg/m3 exposure is 1.1 times the 25 µg/m3 8-hour OEL. The higher OCH exposure exceeded the APF of the worker’s respirator. Exposures during the 40-minute milling and addition of 212 kg of IB were 12,800 and 1,900 µg/m3. IB’s 2,000 µg/m3 8-hour OEL was not exceeded (no STEL), but the 12,800 µg/m3 exposure was 1.3 and 2.1 times the ACGIH excursion limits. High, short-term exposures are especially important for sensitizers because a high induction exposure (e.g., before exposures are assessed) can result in a very low elicitation exposure, even that via normal respirator leakage or incorrect respirator use. Recommendations included better ventilation; modifying work practices, equipment, and packaging; and addressing respirator program deficiencies. This study demonstrates how handling even a small quantity of material can result in significant short-term exposures.
C. Brossia, K. Henry, Amgen, Longmont, CO; C. Ellwood, AOEH, Golden, CO.
Successful biopharmaceutical production involves cGMP manufacturing systems, quality assurance laboratories, process development laboratories, facilities, and myriad support groups. The elements and types of exposure for each group vary dramatically. Designing an employee exposure assessment program that can manage thousands of chemical, physical, and biological potential exposures was a daunting task. First, the method of information collection and storage must be accessible and understandable for future reviews and assessments. Second, the exposure characterization and assessment information, statistical analyses, and exposure profiles must follow a logical course that allows the health and safety manager to make easily presentable and defensible decisions. Finally, the information collected as well as its managing tools must compliment other health, safety, and environmental programs and management systems at the facility. The presentation will illustrate details of the program’s qualitative and quantitative assessment tools and decision logic.
B. Roberge, R. Gravel, S. Buissonnet, N. Goyer, Institut de Recherche Robet-Sauvé en Santé et en Sécurité du Travail, Montreal, PQ, Canada.
In the context of a study to estimate the health and economic impacts of lowering the current threshold limit value (TLV) ceiling of 2 ppm for formaldehyde to a TLV ceiling or time-weighted average (TWA) of 1, 0.75 or 0.3 ppm, the present exposure of Québec workers was evaluated in many economic activity sectors. Knowing the reliability and limits of the measuring methods was then of primary importance. For the TWA, two methods were used in parallel. For the first, formaldehyde was collected on XAD-2 polymer tubes impregnated with hydroxymethyl piperidine, at a flow of 0.2 L/min. The analysis was done by gas chromatography. For the second, formaldehyde was sampled on a passive diffusion badge impregnated with 2,4-dinitrophenylhydrazine (2,4-DNPH) and analyzed by liquid chromatography. More than 200 samples were collected for each method, both in the workers’ breathing zone and ambient air, for periods of 1 to 6 hours. The results showed that both methods were equivalent for a concentration range from 0.07 to 2.0 ppm. For the ceiling exposure, three direct-reading instruments were used in the workplaces. The first one was an infrared analyzer equipped with a photoacoustic detector. The second one was based on a colorimetric reaction with a chemical read by an optical sensor. The third one was an electrochemical cell analyzer. Considering the results together or sector by sector, no correlation can be found between instruments. The presence of other compounds, namely phenol, toluene, and organic solvents, may influence the readings. To verify this fact, a study was done in a test chamber where instruments were exposed to formaldehyde in the presence of chemicals suspected to interfere with the readings. A fourth instrument, another type of infrared analyzer, was also tested. This study showed that potential bias can occur in measuring ceiling exposure.
J. Park, T. Pearce, J. Cox-Ganser, NIOSH, Morgantown, WV.
We examined the effects of storage time, temperature, and humidity on levels of culturable fungi from office building floor dust samples. Four bulk dusts were pooled, homogenized with a 360-degree rotation shaker for two hours, and made into 152 aliquots. For a total of 144 aliquots, four were assigned into 36 combinations of time (two, four, six, and eight weeks; six months; and one year), temperature (room temperature, 4° C refrigerator, and -80°C freezer), and humidity conditions (with and without desiccant). We additionally analyzed eight aliquots two days after sampling to obtain baseline data. The samples were cultured with MEA, DG-18, and cellulose agar at room temperature for seven to 10 days. A total of 44 species were identified with Penicillium aurantiogriseum, Epicoccum nigrum, Cladosporium cladosporioides, yeasts, and Alternaria alternata recovered from at least 70% of the aliquots. Total fungi from all aliquots ranged from 3,500 to 165,400 colony-forming units per gram dust (cfu/g), showing that effects of storage conditions were within two orders of magnitude. We analyzed cfu/g with analysis of variance. Compared with baseline, Penicillium levels generally increased over time up to six months for all temperature conditions, and then dropped at one year. Cladosporium levels generally declined at all temperature and time conditions. Yeasts generally declined up to eight weeks; after that, levels differed by temperature conditions. We found interaction effects between time and temperature that differed by species. At the two-week-long storage, Cladosporium and yeast levels were closest to the baseline values for -80°C storage, while for Penicillium, all three temperature conditions gave similar results. The presence of desiccant kept the levels of Cladosporium and Penicillium species closer to the baseline, but this effect was not found for other species. Our results imply a complicated relationship between storage conditions and levels of culturable fungal species.
A. Panepinto, B. Edwards, K. Herrmann-Ratz, Proctor & Gamble, Cincinnati, OH.
This study was conducted to evaluate worker exposures in consumer tissue manufacture in terms of fibrous dust. The morphology assessment looked at the size and shape of dust particles at the microscopic level to determine specific parameters that will help estimate how the paper dust may behave in the high Reynolds flow encountered in the upper respiratory tract. The fiber composition of the airborne paper dust is minor as determined by analysis of 60 inhalable dust samples collected on personnel. Isometric platelets are 83.8% of the airborne particles. Fibrous particles accounted for only 15.6% of the total particle count. From the microscopic analysis, the isometric particles appear to be formed by the cross-sectional diminution of the ribbon-like cellulose particles used in the process. Many of the particles are curved platelet structures. The sizes of the platelets range from 10 µm ´ 10 µm to 50 µm ´ 50 µm. The ICRP generally defines rigid fibers with a diameter of > 3.5 µm as having a low potential for respirability. It may be inferred that aerodynamically, a nonrigid or nonlinear fiber with a diameter of > 3.5 µm would be even more likely to deposit in the upper regions of the respiratory tract. The mean diameter of the aggregate of fibers from all samples analyzed was 6.5 µm (range, 1 µm–50 µm). The air samples collected in this study were submitted for analysis using three fiber counting methods. The mean fiber counts for the samples as determined by NIOSH Method 7400 A, NIOSH Method 7400 B, and MDHS Method 59, were 0.017 fibers/cc, 0.024 fiber/cc, and 0.011 fibers/cc. This data also demonstrates that the fibrous component of the inhalable dust is small and supports continued application of inhalable dust nuisance exposure criteria for paper-making operations.
G. Whitney, Los Alamos National Laboratory, Los Alamos, NM.
The DOE beryllium rule (10 CFR 850) has led to an increased demand for measuring beryllium surface contamination. As more and more aging facilities are scheduled for D&D, industrial hygienists may have to evaluate the extent of and determine the source of beryllium contamination. Identifying sources can be challenging when contamination is at low levels. Is it naturally occurring beryllium from soils, or an indicator of a possibly greater underlying legacy contamination problem? A method has been developed that provides the concentration of beryllium in the material collected from the surface (ppm), the amount of beryllium on the surface per area (µg/100 cm2), and elemental ratio data that can aid in determining the source of the beryllium. With this method, the filter papers used to collect surface wipe samples are pre-weighed in plastic Petri dishes. Sample are collected and allowed to dry. The filter/Petri dishes are post-weighed and then sent for analysis. Samples are analyzed for beryllium, other elements that may be associated with beryllium in the local soils (often iron or aluminum), and for elements that may be associated with beryllium from specific anthropogenic sources (e.g., lead, copper, or uranium). Elemental ratios and the concentration of beryllium in the material collected on the filter can be compared with local geological data to determine if the beryllium detected on surfaces is consistent with that expected from soils. Elemental ratios can also be used to associate beryllium with metals from site operations. It is concluded that this method is easy, relatively low cost, is of significant value to industrial hygienists, and could be applied to other metals. This method has been used to identify beryllium contamination that was due to wind-blown soil and to confirm that other contamination was due to legacy operations.
J. Jeong, B. Lee, B. Kim, Kosha, Incheon, Republic of Korea; N. Paik, Seoul National University, Seoul, Republic of Korea.
The purpose of this study was to validate an alternative method by using noncarcinogenic, less toxic solvents than NIOSH analytical method 5524 for measuring the airborne metalworking fluids (MWFs) in workplaces. In laboratory tests, the ETM solvents (mixture of same volume for ethyl ether, toluene, and ethanol) were selected, instead of DTM solvent (mixture of same volume for dichloromethane, toluene, and methanol) used in NIOSH analytical method 5524 for MWFs extraction. The alternative method of analyzing MWFs, referred to as the ETM solvent extraction method, showed 0.04 mg/sample as LOD and 0.15 mg/sample as LOQ. This level is sufficient to evaluate compliance to the 5 mg/m3 oil mist-TWA established by the Ministry of Labor in Korea, and also the REL-TWA (0.5 mg/m3) for the MWFs recommended by NIOSH. The analytical precision (pooled CV) of the ETM solvent extraction method for analyzing the straight, soluble, semisynthetic, and synthetic MWFs was 1.5%, 2.0%, 2.6%, and 1.6%, respectively. The analytical accuracy by recovery test, spiked mass calculated as extractable mass, was almost 100%. As the result of storage stability tests, MWFs should be stored in a refrigerated condition and be analyzed two weeks after sampling. The 95% confidence limit of the estimated total standard error for the ETM solvent extraction method for analyzing the straight, soluble, semisynthetic, and synthetic MWFs was ±12.6%, ±12.5%, ±14.0%, and ±13.6%, respectively, which satisfied the OSHA sampling and analytical criteria. In field tests by using the exposure chamber, the overall uncertainty of the ETM solvent extraction method was 21.6%, which satisfied the NIOSH criteria for the sampling and analytical methods. In conclusion, the ETM solvent extraction method using noncarcinogenic and less toxic solvent showed good performance with acceptable accuracy and precision for the determination of all kinds of airborne MWFs in workplaces.
R. O’Mara, D. Saunders, Eli Lilly and Company, Lafayette, IN.
Eli Lilly and Company industrial hygienists often utilize glass Petri dish monitoring programs when conducting containment engineering studies in pharmaceutical manufacturing facilities. A program using Petri dishes basically involves setting out Petri dishes at various locations in the facility for a period of time, typically two to four weeks. At the end of the monitoring period, the dishes are collected and submitted to the laboratory for analysis. The laboratory determines the mass of the analyte, which has settled into the dish over time. The industrial hygienists have developed cleaning requirements and personnel monitoring triggers based on the amount of analyte reported. This program allows generation of data indicating long-term changes in the amount of analyte deposited onto the dish, but the data generated is not indicative of the air concentration of the analyte in the facility. The Lilly Industrial Hygiene Laboratory has developed an alternative to the Petri program for a nonvolatile API salt using cassettes assembled from IOM cassette inlets, polyurethane foam (PUF) discs, and 25-mm cassette parts. One version is strictly for collecting air samples and another version also contains an API-spiked disc to provide field recovery data for the sample. The cassettes are attached to programmable pumps, which sample intermittently (a total of 15 minutes every two hours). The monitoring technique provides the average long-term air concentration in the facility, but more importantly, if an undetected release of material occurred the potential exposure during the release could be determined. A validation study conducted with an API in a manufacturing facility for two weeks demonstrated 95% recovery of the analyte.
P. Gao, NIOSH, Pittsburgh, PA.
System-level evaluation of protective ensembles is increasingly being used to develop performance specifications. For example, the 2006 proposed revision of the NFPA 1994 standard requires particulate integrity tests for class 4 suits. While aerosol penetration tests exist, there is a continued need for better methods suitable for use with human subjects and capable of passively sampling trace levels of particulates at multiple body locations between the skin and the ensemble. Surveying aerosols with properties to facilitate passive sampling, we found iron (II,III) oxide, magnetite, attractive due to low toxicity and cost, availability in several particle sizes and sensitive analytical methods. Magnetite’s magnetic susceptibility allows several isolation and detection schemes; most simply, collection with permanent magnets. However, a coating isolating the iron-containing magnet from the collected aerosol is required to prevent confounding the analysis. In this work, various coatings were evaluated for their compatibility with magnetic sampling and the analytical method. Collected magnetite was dissolved in acid, oxidized, and quantified by spectrophotometry. Method blank was determined to be 1.0 µg. Coatings alone results were silicone (2 µg), epoxy A (81 µg), polyethylene A (2 µg), polyethylene B (3 µg), polyperfluoroethylene (2 µg), and silicone (2 µg). Single coating on iron or magnet results were epoxy A (1,100 µg), epoxy B (> 3,600 µg), gold (575 µg), polyethylene A (3 µg), polyethylene B (3 µg), polyperfluoroethylene (2 µg), and silicone (660 µg). Incomplete coverage and delamination appeared responsible for magnet dissolution, which caused the high iron content in the extract. Double coatings results were epoxy A (10 µg) and silicone (1 µg). Polytetrafluoro-ethylene, silicone, and polyethylene A were selected for further analysis. Monitoring magnet strength and blanks after repeated use indicated that all of these coatings were acceptable. However, polyethylene A was selected for further development based on practical considerations.
B. Law, S. Stone, D. Frazer, P. Siegel, NIOSH, Morgantown, WV.
Asphalt is a complex mixture of aliphatics, polycyclic aromatic hydrocarbons, substituted aromatic compounds, and other miscellaneous compounds. Several methods of quantification have been used to assess fume concentration for industrial hygiene studies. These include benzene-extractable components weight from gravimetric sampling, fluorescent assessment for polyaromatic hydrocarbon (PAH) content, and total fume concentration relative to PAH or kerosene. Finding an appropriate standard to quantify this type of mixture can be difficult, resulting in potential gross quantitative underestimation or overestimation. In the present study, road paving—like asphalt fume—was generated (150°C), collected onto a sampling train consisting of a HEPA filter (particulate phase) followed by XAD-2 (volatile phase), and both were extracted with dichloromethane. Density of the particulate phase was 1.84 g/ml. Kerosene, standard mixture containing 16 priority PAH compounds, and aliphatic standards (C8–C36) were evaluated by gas chromatograph-mass spectrometry (GC-MS) for similarity of simulated boiling point profiles, and relative total ions vs. asphalt fume extracts. Fluorescence methods were also evaluated before and after HPLC separation from aliphatic components using a poly-divinylbenzene column. Fluorescence was found to be problematic for the quantification of total PAHs from this complex mixture. The kerosene reference standards’ boiling point profile was closer to that of the asphalt fume than the other standards evaluated. The total asphalt fume particulate concentration was overestimated (using GC-MS analyses) by 16.7-, 1.8- and 1.7-fold using the PAH mixture, the kerosene reference standard, and the aliphatic reference standard mix respectively. These results underscore the difficulty in assessing and quantifying the concentration of complex mixtures from occupational environments. This research was funded in part by an interagency agreement with NIEHS/NTP, interagency agreement Y1-ES-9045-01.
C. Manning, S. Green, Assay Technology, Pleasanton, CA.
In developing samplers for air contaminants in industrial environments, researchers face three challenges. First, selecting sampling media on which contaminants can be collected, stored, and recovered (e.g., activated carbon for neutral organics). Regardless of sampling media chosen, the other challenges consist of collecting a quantity of contaminant that is large enough to perform accurate analysis and small enough that sampling media capacity is not exceeded. In early active sampling methods, sample capacity was obtained by increasing the mass of carbon in sampling trains (e.g., jumbo tubes and multitube samplers). Later, it was noticed that the goal of increasing the ratio of charcoal mass to sample volume can be achieved equally well either by increasing charcoal mass in the sampling train or by decreasing the air volume sampled. Increasing the mass of sampling media has disadvantages; namely, that multiple tests are required to analyze multiple tubes and extra solvent is required to analyze jumbo tubes. Conversely, if extra sample capacity can be achieved by lowering sampling rate, volatile contaminants may be collected on a small, economical sampler, while modern analytical lab technologies have made analysis of small amounts of contaminants cost-effective and convenient. For very volatile contaminants (including nitrous oxide, methyl bromide, halogenated anesthetics, and methylene chloride) difficult to sample due to inadequate sample capacity, samplers featuring lowered sampling rates (0.5–5 ml/min) have been devised. For semi-volatiles, where detectability is the greater problem (including glycol ethers, aromatic hydrocarbons, and glutaraldehyde), samplers featuring heightened sampling rates (10–50 ml/min) were devised. In this study, holding the mass of sampling media constant (ca. 100 mg) while varying sampling rates provided a single sampler of cost-effective size, while providing the end user with appropriate sample capacity for each contaminant sampled. Sampling rate and capacity parameters for 50+ contaminants on samplers were developed in this study.
D. Cottica, E. Grignani, C. Boaretto, P. Sacco, S. Angeleri, Fondazione Salvatore Maugeri–IRCCS, Padova, Italy.
In the last 20 years, the diffusive sampling technique was developed because of the need for more lightweight and small personal sampling devices and the need to sample gases and vapors in confined spaces and at fires and explosions. Diffusive samplers, based on Fick’s law, are the answer to these problems for industrial hygienists. Diffusive samplers were first developed as “axial or planar” samplers, often characterizd by a very low sampling rate compared with that used in the pumped sorbent tube methods. To increase the sampling rate of the diffusive samplers, Vincenzo Cocheo, past director of the Center, developed Radiello, a radial diffusion sampler with a sampling rate for VOCs in the range of 50–100 ml/min. Since 2000, many normative reference standards have been published by CEN, ISO, and ASTM on diffusive sampling methods. This paper presents the results of an intercomparison between the pumped method and Radiello for workplace air monitoring of n-hexane, benzene, toluene, xylene, ethyl benzene, and MTBE. Pumped and diffusive samplers were used together for personal sampling of about 90 workers in different jobs. The sampling rate of the pumps was adjusted as the medium equivalent sampling rate of Radiello for the monitored substances. The sampling time range was from 6 to 8 hours. All the sampling substrates were solvent desorbed by carbon disulfide and analyzed by HRGC-FID. The intercomparison between pumped and Radiello determinations showed a very good correlation for benzene (R2 = 0,91), toluene (R2 = 0,95), xylene (R2 = 0,92), and n-hexane (R2 = 0,95), with less for MTBE (R2 = 0,80).
Posted May 30, 2006