Evaluation of Airborne Contaminants


Wednesday, May 25, 2016, 5:30 PM - 7:30 PM


Road Paving and Asphalt Fumes—What Affects Exposure Levels?

M. Shum, L. Clements, L. Kimble, and P. Bergholz, Occupational Hygiene & Safety, AMEC Environment & Infrastructure, Burnaby, BC, Canada

Objective: To determine factors that contribute to asphalt fume exposures during paving of hot asphalt mix such as job tasks/activities, type of paving, weather conditions, and time of year. To determine controls available that can help reduce exposures.

Methods: 61 benzene soluble fraction asphalt fume samples and 13 polycyclic aromatic hydrocarbon (PAH) full-shift personal samples were collected at various locations in the Lower Mainland of British Columbia over the course of two years during paving of hot asphalt mix. Personal samples for asphalt fume were collected in accordance with the NIOSH Method 5042. Benzene Soluble Fraction and Total Particulate (Asphalt Fume). Personal samples for PAHs were collected in accordance with NIOSH Method 5515. Polynuclear Aromatic Hydrocarbons were analyzed by GC. Additional sampling is expected to occur between the fall of 2015 and spring of 2016. The data will be analyzed to determine whether factors such as percent recycled asphalt product (RAP), cleaning of the paving machine prior to paving, and additional environmental conditions affect exposure levels.

Results: To date, the sampling results indicate that the exposures for the Paver Operator, Screedman, and Rakerman are often above the occupational exposure limits for benzene soluble fraction of asphalt fume in British Columbia, particularly during extended shifts (greater than eight hours). Polycyclic aromatic hydrocarbon sampling results indicate low levels of exposure for the compounds specified in the NIOSH 5515 method. The job task and rate of paving (e.g., how many tonnes are paved per shift) are the best predictors of exposure.

Conclusions: Results indicate that asphalt road pavers are often overexposed to asphalt fumes during paving of hot asphalt mix. Length of shift and job task are predictors of exposure. Other factors affecting exposure and potential controls will be identified in the coming months.



Formaldehyde Exposure Assessment During the Application of Professional Hair Smoothing Products

M. Posson and R. Kalmes, Exponent, Inc., Oakland, CA

Situation/Problem: Occupational exposures to formaldehyde associated with the use of hair smoothing products in professional salons have been the recent focus of media attention, government agencies, and NIOSH. Initial studies conducted by the authors indicated that short-term exposures above the ACGIH® Ceiling limit (0.3 ppm) occurred during the application and blow-drying stages of the treatment process. The objective of this study was to evaluate the effectiveness of practical administrative and engineering controls to reduce potential exposure to formaldehyde associated with the use of professional hair smoothing products under typical and representative salon conditions.

Resolution: A sampling approach was developed to characterize and evaluate controls to reduce formaldehyde exposures from professional hair smoothing products. Personal and area samples were collected at several commercial hair salons over a 3.5-year period. Samples were collected under typical salon conditions and during one to two treatments. Personal air samples were collected from the breathing zones of hair stylists during the treatments that were conducted in four distinct steps: pre-application preparation, application, blow-drying, and ironing. Task-based air samples were collected to evaluate potential exposure associated with each of the steps. Pre- and post-treatment samples were also collected. Samples were collected and analyzed using NIOSH Method 2016.

Results: A series of exposure controls were developed and evaluated. In some cases, task-specific formaldehyde concentrations were above the ACGIH® Ceiling limit (0.3 ppm), even when implementing controls. However, the treatment process was optimized during the study period and ultimately included a combination of practical administrative and engineering controls.

Lessons learned: The sampling methodology employed provides useful insight into characterizing formaldehyde exposures during treatments and identifying tasks for potential exposure control points during the treatment process. The amount of product used, the manner in which the product was applied and proximity of the stylist to the hair being treated were attributed to the measured formaldehyde exposures. Controls were optimized after several iterations.



Application of a Novel Personal Air Sampler

J. Herrington, M. Lininger, J. Konschnik, and S. Kozel, Innovations Group, Restek Corporation, Bellefonte, PA

Objective: The AURA™ Personal Air Sampler (PAS) passively collects an 8-hour whole air sample via vacuum in a 400 mL canister. The sampler was developed to help environmental and occupational health experts monitor for personal exposures to airborne volatile organic compounds (VOCs). The PAS was designed as an alternative to diffusive sampling badges and/or active sampling with sorbent tubes. PAS was engineered to avoid some of the short-comings associated with said approaches. A field study applying the PAS and the most popular competing technologies has been executed to see how well it compares on multiple variables.

Methods: A field study was conducted in an occupational setting in which PAS where located on subjects along with diffusive sampling badges and/or sorbent tubes. Samples were collected over an 8-hour sampling duration and compared for VOCs applicable to both methods.

Results: Results indicate that the PAS results correlate very well with the results obtained from diffusive sampling badges and sorbent tubes. For example, thermal desorption (TD) tube results and PAS results for 13 subjects had a coefficient of determination of 0.92 for methylene chloride.

Conclusions: The AURA™ PAS is able to provide comparable results to diffusive sampling badges and active sampling with sorbent tubes. The PAS does this while avoiding some of the short-comings associated with the latter approaches. For example, the PAS does not require a pump and is therefore quiet; and manages variations in face velocity, temperature, and humidity better than traditional sampling approaches. In addition, the PAS is easy to operate with a simple quick connection to start and stop flow; and therefore does not require flow calibration. Lastly, the PAS is a whole-air sampling approach, which affords multiple analyses of over 100 VOCs; and is sensitive down to pptv levels, while not subject to sample breakthrough at ppmv levels.



Association Between Personal and Area Fiber Concentrations in Brake Repair Shops: Analysis in a Real-Life Setting

L. Méndez García, M. Cely-Garcia, M. Giraldo, and J. Ramos-Bonilla, Civil and Environmental Engineering, Universidad de Los Andes, Bogota, Colombia; P. Breysse, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; M. Duran, C. Torres-Duque, M. Gonzales-Garcia, and P. Parada, Fundacion Neumologica Colombiana, Bogota, Colombia

Objective: In the past, area asbestos concentrations were commonly used to estimate personal exposures to asbestos in occupational settings. Several studies have found this practice inadequate since personal fiber concentrations tend to be higher compared to area concentrations. However, other studies suggest that there is no difference and that a strong correlation exists between area and personal samples. This study evaluates the association between personal and area fiber samples, in brake repair shops that currently manipulate asbestos containing friction products.

Methods: Personal and area samples were collected in two brake repair shops in Bogotá (Colombia) in September and December 2014. Personal samples were collected from one brake mechanic at each shop. In both shops, area and personal asbestos samples were collected simultaneously in time windows of 2-hours, during the 8 hours work shift for one week. Phase Contrast Microscopy (PCM) fiber concentrations were determined using NIOSH method 7400. A longitudinal based linear regression model was used to evaluate the association between personal and area asbestos concentrations.

Results: Important differences in work practices were observed between the workers sampled. In shop 1, the mechanic constantly left the manipulation area (i.e., which resulted in an intermittent exposure), while the mechanic in shop 2 remained most of the time at the manipulation area. The results of the model suggest that for the worker from shop 1, personal fiber concentration increases 61.14% (p = 0.073) per each additional increase in area fiber concentration. For the worker from shop 2, fiber concentration in personal samples was expected to increase 550.08% (p = 0.012) for each additional increase in fiber concentration in area samples. In both cases, the association was observed between fiber personal concentrations and fiber area concentrations collected at the source of the fibers (i.e., manipulation equipment). No significant associations were observed with area samples collected at other locations of the shop.

Conclusions: A significant association between area and personal fiber concentration was only observed in very specific circumstances. The association is highly dependent on the location of the area monitor and the time the worker spent at the manipulation area.



Formaldehyde Emissions from Laminate Flooring: Is There a Proposition 65 Exposure Issue?

P. Sheehan, A. Singhal, R. Kalmes, and K. Bogen, Exponent, Oakland, CA

Situation/Problem: There has been much in the news recently about formaldehyde emissions from laminate flooring manufactured in China. The scientific literature has little information regarding the potential long term exposures of individuals who install this laminate flooring. California’s Safe Drinking Water and Toxic Enforcement Act of 1986, commonly referred to as Proposition 65, lists formaldehyde as a chemical known to the State to cause cancer and requires that products that emit formaldehyde either be shown to pose an exposure below the safe harbor daily dose for formaldehyde (40 µg/day) or be properly labeled as a carcinogen.

Resolution: We have conducted a Proposition 65 exposure assessment for 26 types of Chinese manufactured laminate flooring. Samples of each type of laminate flooring were initially tested in a controlled environmental chamber to estimate formaldehyde emission rates. The emission rates were included in a probabilistic model of household exposure along with other parameters to estimate the distribution of formaldehyde concentrations in indoor air at initial steady-state levels after installation. A new evaluation of emissions decay with time for particle board laminates was used to develop a decay curve for indoor formaldehyde concentration from laminate flooring. This decay curve was then applied to the initial concentration distribution to characterize the distribution of time-weighted average (TWA) concentrations over various time intervals during the expected use life of the product.

Results: From this analysis, the TWA indoor formaldehyde concentration experienced by a typical resident over the 10 year mean residency period is estimated to have an expected value of ~0.76 µg/m3. Applying a conservative inhalation rate of 20 m3/day and accounting for the average fraction of the day spent at home (0.68), the daily dose of formaldehyde from laminate flooring is expected to be ~10 µg/day.

Lessons learned: This dose is only approximately 25% of the Proposition 65 safe harbor level for formaldehyde, indicating that this laminate manufactured in China poses a negligible risk under Proposition 65 and could be sold in California without a warning label.



Conducting Smoke Testing for Placement of Near Real Time (NRT) Monitoring Utilizing the EPA DQO process

J. Brooks, Bechtel, Pueblo, CO

Situation/Problem: The Pueblo Chemical Agent Pilot Project is tasked with the destruction of the remaining US Army stockpile of assembled chemical weapons containing sulfur mustard agent (Bi​​​s-(2-chloroethyl) sulfide). The processing requires removal of the energetic (propellant and explosive) components from the munition. This is followed by munition cavity exposure for draining the sulfur mustard agent for treatment with high temperature water and sodium hydroxide. The resulting neutralized waste mixture is then biotreated for disposal. While much of the process is automated, potential employee exposure occurs through the munitions transport, energetic removal, and maintenance and repair of automated equipment cycles. NRT monitoring is conducted with MINICAMS® to detect potential agent exposures as early as possible to prevent exceedance of STEL and TWA established concentrations. The MINICAMS® NRT is an area air monitor which necessitates optimal placement based on potential process release points, ventilation characteristics of the facility, and location of the workers. Typically, NRT monitoring location siting has been conducted at nuclear and chemical demilitarization facilities by smoke testing using qualitative assessments by Industrial Hygiene and Health Physics professionals. The qualitative aspects (release and tracing to sample point collection end) has lacked the specificity to optimize the location for early detection.

Resolution: PCAPP has utilized the EPA Data Quality Objective (DQO) seven (7) step model process incorporating the variable of time to quantify optimal placement of NRT devices. Particular attention was given to step five (develop a decision rule) and step six (specify tolerable limits on the decision error) in developing detailed test plans and procedures. Successful testing was based not on adequacy but on optimization under this process to provide the best detection possible to prevent worker exposures.

Results: The application of the EPA DQO model has resulted in optimal placement of NRT sample collection points that may have not been obvious using typical testing techniques.

Lessons learned: The use of DQO processes in siting NRT or Real Time air monitors provides for optimal placement in the protection of workers needing immediate notification of potential exposures.​