Poster Session 1

Poster Session 1

Author Attend Time: Monday 10:00 a.m. - 12:00 p.m.

*All posters are available for viewing in the expo hall from Monday 9:00 a.m. through Wednesday 1:00 p.m.

SR-401-01 Size Distribu​​tion and Estimated Respiratory Deposition of Total Chromium, Hexavalent Chromium, Manganese and Nickel in Gas Metal Arc Welding Fume Aerosols

L. Cena, M. Keane, A. Cumpston, B. Chen, NIOSH, Morgantown, WV

Objective: Assess the particle size distribution from 10 nm to >30 μm of total Cr, Cr(VI), Mn and Ni in welding fumes generated by GMAW of mild and stainless steel, establish the fraction of Cr(VI) in total Cr for each particle size range, and provide an understanding of the regional deposition of these metals in the human respiratory system.

Methods: Welding fumes were generated with a robotic welder operating in axial spray mode. Samples were collected using a nano multiple orifice uniform deposition impactor with polyvinyl chloride filters on each stage. The filters were analyzed by inductively coupled plasma mass spectrometry and ion chromatography. Limits of detection and quantitation were experimentally calculated and percent recoveries were measured from metal spikes. The fraction of Cr(VI) in total Cr was assessed by calculating the ratio of Cr(VI) to total Cr mass for each particle size range. Regional deposition of each metal was estimated according to respiratory-deposition models.

Results: The weight percent (wt%; ± standard deviation) of Mn in mild steel fumes was 9.2% (±6.8%). For stainless steel fumes, the wt%s were 8.4% (±5.4%) for total Cr, 12.2% (±6.5%) for Mn, 2.1% (±1.5%) for Ni and 0.5% (±0.4%) for Cr(VI). All metals presented a submicron fraction between 0.04 and 0.6 µm. Total Cr and Ni presented an additional fraction <0.03 µm. On average 6% of the Cr was found in the Cr(VI) valence state. There was no statistical difference between the smallest and largest mean Cr(VI) to total Cr mass ratio (p-value=0.19), hence particle size did not affect the contribution of Cr(VI) relative to total Cr. The predicted total respiratory deposition for the metal particles was ~20%. The sites of principal deposition were the head airways (7-10%) and the alveolar region (8-9%). Estimated Cr(VI) deposition was highest in the alveolar region (8.8%).

Conclusions: Total fume mass obtained from gravimetric analysis of the impactor stages presented a tri-modal distribution with a substantial contribution of particles in the 0.006–0.06 μm range. Chemical analyses of the individual metals did not reveal as prominent mass in this smaller size range. The discrepancy may be due to the lesser reliability of gravimetric analysis compared to chemical analysis. The wt% of metals in the fumes differed from that of the consumables. Future research should focus on other welding processes such as SMAW, FCAW and gas tungsten arc welding. 

SR-401-02 Developing and Validating of a New Filter Holder for Direct On-filter Analysis of Free Silica Samples by Using the XRD Method

C. Chen, P. Tsai, National Cheng Kung University, Tainan City, Taiwan; C. Lai, Chung Shan Medical University, Taichung City, Taiwan-

Objective: This study was set out to develop a new filter holder for direct on-filter (DOF) analysis of free silica samples using the XRD method.

Methods: The target uniformity of the deposition of particles on a filter (=0.78) was determined according to NIOSH-7500 method, and was used as a guideline for developing a new filter holder suitable for both the nylon cyclone and 25-mm aluminum cyclone.

Results: A new filter holder with an120° outlet angle and a 50mm cowl length was developed based on repetitive laboratory tests. Field validations were conducted on three selected workplaces in a foundry plant. For any given workplace, two nylon cyclones respectively mounted with a traditional and a newly developed filter holder (denoted as T-Nylon and N-Nylon, respectively) , and two 25-mm aluminum cyclone respectively mounted with a traditional and the newly developed filter holder (denoted as T-AL and N-AL, respectively) were used to collected respirable dust samples. Results show that no significant difference was found among the respirable dust concentrations for samples collected from the T-Nylone, N-Nylone, T-AL and N-AL suggesting that all testing cyclones shared a very similar performance as a pre-selector for collecting the resparable dust. The quartz concentrations for samples collected from T-Nylone and T-AL analyzed using the DOF XRD method were found to be higher than that of the NIOSH-7500. On the other hand, quartz concentrations for samples collected from N-Nylone and N-AL, while analyzed using the DOF XRD method, were found with no significant difference from those analyzed using the NIOSH-7500 method.

Conclusions: It is concluded that the developed filter holder is suitable for collecting and analyzing respirable free silica samples using the DOF XRD method, which will be beneficial for industries on reducing both cost and manpower on free silica analysis as in comparison with the use of the NIOSH-7500 method.

CS-401-03 Controlling Open Pit Mine Ground Worker Respirable Silica Exposure: A Case Study

D. Weber, Liberty Mutual Insurance Company, Glastonbury, CT

Situation/Problem: Open pit mining and crushing of stone provides needed material for the construction industry. A ground worker commonly works around crushing and conveying equipment. The ground worker cleans up material spills from conveyors, picks stone from catwalks and monitors feed piles, material transport and tunnel operations. During these activities, excessively high airborne exposure to respirable dust containing crystalline silica (quartz) was present. Excessive respirable quartz exposure has been linked to lung fibrosis and silicosis. The ground worker’s exposure to respirable dust containing quartz was over 2 times the MSHA PEL. The worker wore a NIOSH approved N95 filtering facepiece respirator. Industrial hygiene recommendations following the hierarchy of controls were submitted with emphasis on the need for enhanced dust suppression at crushing and transfer points.

Resolution: Management actions included the installation of cameras for observing the tunnel, the top feeds of the secondary and recrush/tertiary crushers, permitting the worker to spend more time in the control trailer. Cleaning was eliminated in the vicinity of the primary ground area while the primary crusher is operating. Conveyor skirting was improved to reduce spills that required clean up. Improvements in water mist dust suppression were implemented at the secondary and tertiary crushers and at belt transfer points. The employee wears task-based appropriate NIOSH approved respiratory protection in the form of N95 filtering face piece respirators as needed and is included in an effective Respiratory Protection Program.

Results: The enhanced controls resulted in the ground worker’s respirable dust exposure being reduced to below the MSHA PEL.

Lessons Learned: A combined effort of modified work procedures, remote process equipment monitoring in conjunction with well designed, managed and maintained water mist dust suppression can provide effective means of reducing crushing plant ground worker respirable quartz exposure.

SR-401-04 Exposure Level of Airborne Fungi in Pig Buildings of Korea

K. Kim, Catholic University of Pusan, Busan, Republic of Korea; H. Ko, Korean National Open University, Seoul, Republic of Korea; C. Kim, Yonsei University, Seoul, Republic of Korea

Objective: This study was performed to assess exposure level of airborne fungi in a pig building of Korea according to pig housing type.

Methods: The pig building surveyed in this study was enclosed type operated with mechanical ventilation system and manure removal by slurry pit. The sampling sites in pig building were gestation/farrowing room, nursery room and growing/fattening room. It was visited every month in 2012 and the mean data obtained for three consecutive months were considered as a seasonal level: spring (Mar. to May), summer (Jun. to Aug.), autumn (Sep. to Nov.) and winter (Dec. to Feb.). Samples were collected at 1.5 m above the middle floor in pig housing room. A six-stage viable particulate cascade impactor was used to collect airborne fungi in the pig building. The plate media for culturing airborne fungi was a Malt Extract Agar (MEA). The statistical analysis was applied to verify the significance of concentration difference in airborne fungi among pig housing rooms and seasons.

Results: Mean concentration of airborne fungi in the housing room of gestation/farrowing pigs were 3,004(±1,208)cfu m-3 in spring, 2,536(±1,313)cfu m-3 in summer, 1,568(±836)cfu m-3 in autumn, and 2,324(±1,315)cfu m-3 in winter, respectively. Mean concentrations of airborne fungi in the housing room of nursery pigs were 4,780(±2,008)cfu m-3 in spring, 4,117(±1,836)cfu m-3 in summer, 1,796(±922)cfu m-3 in autumn, and 2,650(±1,235)cfu m-3 in winter, respectively. Mean concentrations of airborne fungi in the housing room of growing/fattening pigs were 11,686(±3,864)cfu m-3 in spring, 16,173(±3,805)cfu m-3 in summer, 1,994(±736)cfu m-3 in autumn, and 7,983(±925)cfu m-3 in winter, respectively. Overall airborne fungi which have particle size over 2.1㎛ (stage 1~stage 4) accounted for approximately 70~80% compared to total airborne fungi regardless of pig housing type. The predominant airborne fungi in pig building were Penicillium sp. (15~25%), Cladosporium sp. (10~15%) and Aspergillus sp. (5~10%).

Conclusions: Exposure level of airborne fungi in terms of pig housing type were highest in growing/fattening housing room followed by nursery housing room and gestation/farrowing housing room (p<0.05). The pig building showed the highest levels of airborne fungi in summer followed by spring, winter and autumn. There was, however, no significant difference among seasonal exposure levels (p>0.05).

SR-401-05 Filtration of Comb​ustion Aerosols by N95, R95 and P95 Filtering Facepiece Respirator Filters

S. Gao, S. Grinshpun, J. Kim, M. Yermakov, Y. Elmashae, T. Reponen, University of Cincinnati, Cincinnati, OH; X. He, West Virginia University, Morgantown, WV; 

Objective: To evaluate the performance of filter samples from an N95 filtering facepiece respirator (FFR) against combustion aerosol particles and conventional NaCl aerosol challenge. While interpreting the data acquired for N95 filters, a secondary goal was established: to conduct the same evaluation for R95 and P95 filters.

Methods: First, 38.5 cm2 filter samples were cut from an N95 FFR and mounted on a holder. The filters were challenged with three combustion aerosols (generated by burning wood, paper and plastic) and with NaCl aerosol. The sample surface area and flow rate were chosen to match the average face velocity through the entire respirator operating at inhalation flow rates of 15, 30, 55 and 85 L/min. The size-resolved particle concentrations upstream (Cup_dp) and downstream (Cdown_dp) were measured with a Nanocheck (Grimm Technologies, Germany). The size-resolved particle penetration (Pdp) was determined as (Cdown_dp/Cup_dp)×100%. Second, the penetration was similarly determined for R95 and P95 FFRs. 

Results: For the N95 filter, the combustion particles featured significantly higher penetrations than NaCl (p<0.05). Increasing the inhalation flow resulted in an increase in Pdp for all challenge aerosols. The particle size, inhalation flow rate and challenge aerosol type were significant factors (p<0.05) affecting the penetration of combustion particles. The most penetrating particle size (MPPS) ranged from 35 to 105 nm and depended on the aerosol type. In contrast to N95, the data collected with R95 and P95 filters provided no evidence of a greater penetration of combustion particles compared to that of NaCl. This difference suggests that “oily” particles generated during combustion could reduce the particle collection efficiency of N-type filters, which are not designed to against “oily” materials, while no similar negative effect occurs for the R- and P-types that are capable to operate in “oily” environments. Other mechanisms that can explain the finding of this study include chemical reactions between the combustion particles and the fibers, as well as electrostatic effects.

Conclusions: The N95 filter performance obtained with NaCl particles may not accurately predict (rather overestimate) the protection level offered by the same filters against combustion particles. R95 and P95 FFRs could offer better protection against combustion particles than N95 FFR.

CS-401-06 Airborne Lead and Arsenic Exposures Arising during Metal Bridge Deck Demolition: A Case Study

D. Weber, Liberty Mutual Insurance Company, Glastonbury, CT

Situation/Problem: The renovation of a bridge with a metal deck required the removal of the metal deck from structural frame members in sections. Torch cutting was employed to cut the deck into sections. During this process, excessively high airborne concentrations of lead were present outside of the torch operator’s respiratory protection. One individual’s air sample contained excessive airborne arsenic. Excessive lead exposure has been linked to neurological, gastrointestinal and heme synthesis affects. Excessive arsenic exposure has been linked to gastrointestinal effects and cancer. Sampling revealed exposures that could represent acute as well as chronic health hazards. Torch cutting worker TWA exposures outside the PAPR’s were in excess of 30 times the lead PEL and slightly above the arsenic PEL. Air samples collected inside one workers PAPR revealed no quantifiable lead exposure for the worker wearing the PAPR continuously. Another worker removed his PAPR on the bridge deck to consume beverages for a short period of time resulting in his sample containing 2.6 ug/cu.m. of lead. Worker protection consisted of Tyvek  suits, gloves and NIOSH approved PAPR’s equipped with and P100 filters. Beverage consumption and smoking were permitted on the bridge deck. Industrial hygiene recommendations following the hierarchy of controls were submitted with emphasis on the need for management to act expeditiously to implement lead and arsenic control programs.

Resolution: Management actions included investigating other suitable means of bridge deck demolition, implementation of a comprehensive lead and arsenic control programs. Requiring all workers on the bridge deck to wear accepted PPE, the elimination of ingestion and smoking on the bridge deck. Management was investigating the acquisition of a sectional trailer for washing, showering and changing clothes.

Results: These exposures were managed for the duration of the job as management continued to investigate other suitable means for metal bridge deck demolition for future jobs.

Lessons Learned: Pre-construction planning for comprehensive management of metal fume exposures arising from bridge deck demolition is critical. If worn properly, PAPR’s provide an effective means of airborne fume exposure control.

CS-401-07 Performance of Ergonomic Evaluation of Identified Plant Site Job Positions for Development of Specific Physical Demands Assessment and Revised Job Description Documentation

J. Koehn, L. McKelvey, W. Young, JK, Inc., Houston, TX

Situation/Problem: Professional and technical consulting services were requested by an industrial plant manufacturing Client to perform ergonomic evaluations for outlined job positions with specific physical demands including work task assessments at a facility located in Houston, Texas during 2013–2014. Review of prepared position descriptions and work activities was completed for a defined consulting scope of work to update documented and defined criteria subsequently used for job placement by nursing personnel working through Human Resources.

Resolution: A project team was assembled for defined plant site assessment of prioritized job work tasks and to prepare necessary documentation. The consulting team members included a Certified Industrial Hygienist (CIH), field/plant knowledgeable Industrial Hygienists, and a Certified Professional Ergonomist (CPE). Observations of physical and strenuous job tasks, noted work positions, and specific manual activities for operations, maintenance, and support groups were gathered for ergonomic quantification of risk levels for the Client. Process included extensive recordkeeping in addition to professional and technical evaluation, personnel interviews, administration of job position surveys, and work task investigation and documentation.

Results: Technical content of the outlined physical assessment categories related to health risk hazards and specific ergonomic work task evaluation was properly addressed through definition of two different conditions as “normal or representative” and also “worst case scenario”. Specific job positions were investigated including recordkeeping through digital photographs and videos for accurate assessment and quantification of required physical demands. Updated job description documents for use by plant site nursing personnel related to new employee hiring procedures and position placement were finalized.

Lessons Learned: Industrial hygiene and plant operations knowledge was valuable for this project to facilitate plant site assessment and categorize risk levels for various job positions. Review of observed work task documentation provided specific quantification of noted repetitive activities with ergonomic risk assessment of required manual and strenuous components. This information was further employed by plant Human Resources personnel to outline elements of pre-employment physical assessment procedures for job position evaluations.

SR-401-08 Field Study of High Flow Rate Respirable Size Selective Samplers for Silica Measurement

T. Lee, M. Harper, M. Kashon, NIOSH, Morgantown, WV

Objective: To determine the feasibility of utilizing the high flow rate samplers (CIP10-R, FSP10 and GK2.69) in measurements of respirable crystalline silica collected from various occupational environments by comparison with low flow rate samplers (10-mm nylon cyclone and Higgins-Dewell type cyclone).

Methods: Samples were collected in seven occupational sites in the US, including construction (masonry and demolition), silica sand production, metal mine and labor union training centers, and five stonemasonry sites in Ireland. Side-by-side personal sampling was conducted with 6 combinations of high and low flow rate samplers. When personal sampling was unavailable, a stationary Lippman-type sampling apparatus was utilized and placed near the working area. Gravimetric analysis was used to determine respirable dust mass concentration and X-ray diffraction analysis was used to determine quartz mass concentration.

Results: Eleven sets of area samples and 268 pairs of personal samples were obtained. Due to large variation in field condition, the respirable dust mass and quartz mass concentrations ratios <0.3 and >3.0 between the high and low flow rate samplers were considered as outliers. The frequency of samples above the limit of detection of quartz (5µg) was significantly (p<0.05) higher when the CIP10-R and FSP10 samplers were used compared to low flow rate samplers while the GK2.69 cyclone did not show significant difference from low flow rate samplers. The same result was produced in the frequency of above limit of quantification (15 µg) between high and low flow rates samplers. Some pairs of the samplers showed significant differences (p<0.05) in respirable dust mass concentration and quartz mass concentration but these differences disappeared when outliers were removed. Some pairs of the samplers showed a significant difference from a 1:1 relationship in accordance with linear regression analysis when outliers were removed. However, while the differences were significant, they are not large.

Conclusions: The high flow rate samplers did not generally show significant differences in respirable dust mass and quartz mass concentration. The high flow rate samplers also provide more dust for subsequent sample analysis, allowing for better precision. However, higher flow-rate samplers may have other attributes that could influence the decision as to whether they should be used for personal sampling. 

SR-401-09 Measuring Workers’ Exposure to Metals in Smelter Materials Used as Fill and Assessing Potential Risk

L. Beyer, M. Seeley, G. Greenberg, B. Beck, Gradient, Cambridge, MA;; S. Thakali, URS Corporation, Philadelphia, PA; F. Melnikov, Yale University, New Haven, CT

Objective: Smelter material (brick, smelter residue, retort), has been used for road construction in the US. When workers handle these materials while repairing roads and bridges, metals could be transferred to hands and subsequently ingested, resulting in a potential health risk. We conducted a hand transfer study to simulate potential exposure. Our objectives were to measure the amount of metals workers might get on their hands as a result of contacting the smelter material used as fill, estimate intake by workers potentially contacting the materials, and assess risk.

Methods: We evaluated exposure to metals from direct contact with smelter material following a study procedure based on peer-reviewed methodology. Smelter material was collected alongside roads and bridges and shipped to a laboratory where, according to a detailed protocol, volunteers handled the material in a manner simulating how workers would contact the material. The volunteers’ hands were then rinsed, and the rinsate was analyzed for lead, zinc, arsenic, and cadmium. Using the analytical results, as well as site-specific information regarding potential worker contact with smelter materials and standard US EPA risk assessment methodology, we calculated exposure from dermal contact and inadvertent ingestion of material on hands.

Results: The maximum amount transferred to the hands for cadmium, lead, and zinc was 0.002, 0.035, and 0.98 mg, respectively. Zinc was detected most frequently and at the highest concentration, lead and cadmium were each detected in two samples, and arsenic was not detected. We calculated a hazard quotient (HQ) of 0.017 for cadmium (ingestion and dermal contact) and 0.0015 for zinc (ingestion only, as there is no dermal absorption). The total hazard index was 0.02. For lead, we estimated the daily intake of 1.96 μg for a 70-kg man, which would have no detectable impact on blood lead levels. None of the detected metals are considered carcinogens via ingestion, so handling smelter material would not be associated with excess cancer risk.

Conclusions: Based on the study results and risk calculations, handling smelter material did not represent a significant source of exposure, and the potential health risks associated with workers handling smelter material did not exceed acceptable risk levels. Nonetheless, exposure could be decreased through use of appropriate protective gloves.

CS-401-10 A Comparison of the Use of Differing Occupational Exposure Limits Using Real World Silica Exposure Measurements

E. Reed, R. Newton, Liberty Mutual Insurance Company, Wheat Ridge, CO

Situation/Problem: The application of occupational exposure limits for silica exposures has long drawn attention from legislators, lobbyists, field practitioners, worker’s rights advocates and industry leaders. A Notice of Proposed Rulemaking (NPRM) published by OSHA which suggests a reduced Permissible Exposure Limit for crystalline silica has heightened interest amongst many industry trade groups and associations.

Resolution: This paper examines exposure data for respirable crystalline silica exposures from 185 field measurements collected at 33 different sites in 6 States, for 28 different similar exposure groups on 50 different dates over a seven year time span. This real-world exposure data was analyzed to develop a comparison of the % of the worker population that would be over-exposed when compared to four different occupational exposure limits for crystalline silica: 1) 29 CFR 1926.55 (OSHA Construction Standard), 2) 30 CFR part §56.5005 (MSHA Standard) / 29 CFR 1910.1000 Table Z-3 (OSHA General Industry Standard), 3) Newly Proposed OSHA PEL (Federal Register, September 12, 2013), and 4) the 2014 ACGIH TLV®.

Results: Percentages of worker populations that would be over exposed are reported for 28 similar exposure groups (SEGs) as compared with the five referenced occupational exposure limits.

Lessons Learned: The purpose of this paper is to provide insights on the application of differing occupational exposure limits using real world data. 

CS-401-11 Use of Direct Reading Aerosol Monitors to Evaluate Exposures to Respirable Dusts Containing Crystalline Silica

M. Wiggins, Liberty Mutual Insurance, Lexington, SC

Situation/Problem: Evaluating silica exposures can pose challenges due to limitations of the sampling method. Due to the high sample volume requirements, it is difficult to evaluate dust exposures that occur due to performing individual work tasks that create exposures. Direct reading aerosol monitors can be used to evaluate respirable dust exposures during specific work tasks, which can be useful for estimating silica exposures that occur due to specific work operations/tasks. 

Resolution: Direct reading aerosol monitors were used to evaluate respirable dust exposures, in conjunction with using NIOSH method 0600/7500. The direct reading aerosol monitor can help identify sources of exposure and can support recommendations concerning engineering controls and required respirator usage. 

Results: Direct reading monitors can be configured to collect personal breathing zone air samples. If the percentage of crystalline silica that is typically present in the dusts is known, dust exposures can be estimated during specific work tasks/ operations. 

Lessons Learned: Prior or concurrent air sample data using NIOSH method 0600/7500 is needed in order to estimate exposures during individual tasks or specific operations. While the results may not directly correlate to sample results obtained using NIOSH method 0600/7500, the data obtained from the aerosol monitor can be used for identifying tasks /exposure sources that contribute to excessive exposures. Although the use of direct reading monitors is not a substitute for using established NIOSH sampling method, it can be a useful tool for evaluating exposures. Data obtained from use of direct reading aerosol monitors can be incorporated in to performance based exposure determinations.

CS-401-12 Industrial Hygiene Turnaround Support Services

W. Yip, National University of Singapore, Singapore

Situation/Problem: In the petrochemical and refining industry, a turnaround is probably one of the most highly hazardous events that it has to deal with. A turnaround is an event whereby the entire plant is being brought offline so that most of its work such as inspection, repair, replacement and alteration can be carried out. These events are not only expensive and time-consuming but it can also be very complex and labor intensive. With many competing factors, it is crucial that the industrial hygiene support towards such an event be well planned so that the health hazards are addressed. This case study serves to provide guidelines for developing plans and providing IH support for turnarounds.

Resolution: Industrial hygiene (IH) provides guidelines for developing plans and IH support during turnarounds (TA). IH involvement starts from integration of IH elements in work plan during the planning phase prior to TA and ends after the post turnaround review. Below is a list of IH activities performed during the TA in chronological order: Pre TA: Integration of IH into TA planning cycles; Evaluation and identification of potential health hazards during turnaround; Determining control measures for managing the hazards; Identify health regulatory requirements; Assessment of IH monitoring needs and responsibilities; Develop IH Plan; and provide pre-TA support. During TA: Periodically conduct field checks/walkthroughs of TA areas; Use of verification tools to measure success in meeting occupational health standards; Follow up on IH emphasis areas; and Dedicate available resources to area where greater risk exists

Results: By communicating & getting involved in the early planning stages of the TA organization, it will ensure that the TA organization is aware of the IH requirements and needs. This will provide sufficient time for preparation and planning and ensure that resources will be made available to the IH. During TA, IH activities are more field based verification checks and this will help verify whether if the recommendations put in place are adequate.

Lessons Learned: In order to learn, improve and be better prepared for the next TA, IH typically will conduct the following post TA activities: Conduct post TA reviews and feedback; Review of exposure monitoring data; Review of IH TA checklists for trends, significant successes or failures; Update IH procedures if required; Participate in post -TA critiques; and Document learnings.

SR-401-13 Reducing Welders’ Exposure to Manganese Welding Fume Using Low Manganese Emissions Flux Core Wire

J. Capuzzi, ESIS, Cape May Courthouse, NJ

Objective: The purpose of this study is to determine if welders’ exposure to manganese welding fume is reduced by substituting low manganese emissions flux core wire for the standard flux core wire. 

Methods: Full shift or representative full shift personal breathing zone samples were collected for welding fumes using 25mm mixed cellulose ester filter sampling cassettes at a flow rate of 1–2 liters per minute. SKC AirChek sampling pumps provided the vacuum source. Pumps were calibrated prior to and after the sample collection using a TSI 4100 Series mass flow meter traceable to the National Institute of Standards and Technology in conjunction with the filter media. The filter cassette was placed inside the welding helmet. Ten welders using the standard flux core wire (Hobart Formula XL-550 flux core welding wire) were monitored on day one of the study while conducting typical welding activity on railroad tank car parts and tanks. Ten welders using the low manganese flux core wire (Hobart Element 71T1C low manganese emissions flux core wire) were monitored on day two of the study while conducting typical welding activity on railroad tank car parts and tanks

Results: The mean worker exposure using the 71T1C low manganese flux core wire was 0.359 mg/m3 which represent a reduction from the baseline XL-550 wire mean of 1.02 mg/m3. The Mann-Whitney U-test showed that the difference between the data was statistically significant at α = 0.05. None of the exposure concentrations measured using the 71T1C low manganese flux core wire was less than the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) of 0.02 mg/m3 as an 8-hour time-weighted average (TWA) for manganese despite the significant reductions in exposure concentration shown. 

Conclusions: The low manganese emissions flux core wire did have a statistically significant desired outcome of reducing welders’ exposure to manganese. The use of the low manganese emissions flux core wire is recommend if it is technically feasible and meets the welding quality requirements/specifications. The low manganese emissions flux core wire in conjunction with other control measures such as local exhaust ventilation, which was not used during this study, and welder awareness training is also recommended to aid in reducing welders’ exposure to manganese welding fume as well as to other welding fume. ​