Research Property Management Reports Coordinator (OCAI- Faith G. Costello. Mr. John G. Birdsong Vice President

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1 GEOtIGIA INSTITUTE OF TECHNOLOGY PROJECT ADMINISTRATION DATA SHEET OFFICE OF CONTRACT ADMINISTRATION Project No. A-3219 X ORIGINAL DATE 4/13/82 REVISION NO.. Project Director: James L. Burson 4XX9\a/Lab EDL/SHS Sponsor: Centaur Associates, Inc. Type Agreement: Acceptance Letter, dtd. 4/7/82 with Proposal ED SHB Award Period: From 2/17/82 Sponsor Amount: $24,475 To 5/31/82 (Performance) 5 / 31 / 82 (Reports) Contracted through: Cost Sharing: Title: Technical Support for Study of Occuputional Exposure to Cotton Dust. GTRI/Gfor ADMINISTRATIVE DATA 1) Sponsor Technical Contact: Mr. John G. Birdsong Vice President Centaur Associates, Inc. Suite Connecticut Ave. NW Washington, D.C (202) Defense Priority Rating: N/A OCA Contact Faith G. Costello 2) Sponsor Admin/Contractual Matters: Mr. John G. Birdsong Vice President Centaur Associates, Inc. Suite Connecticut Ave. NW Washington, D.C (202) Security Classification: N/A COMMENTS: op21p22,.? - st Lr) 90c5Ibl;, AilaildlitafWeXIMORNiXot C Research Secu rity e Research Property Management Reports Coordinator (OCAI- Accounting Legal Services (OCA) Procurement/EES Supply Services Library EES Public Relations (2) Computer Input Project File Other

2 1 GEORGIA INSTITUTE OF TECHNOLOGY OFFICE OF CONTRACT ADMINISTRATION SPONSORED PROJECT TERMINATION SHEET Date 2/18/83 Project Title: Technical Support for Study of Occuputional Exposure to Cotton Dust Project No: A Project Director: James L. Burson Sponsor: Centaur Associates, Inc. Effective Termination Date: 5/31/82 Clearance of Accounting Charges: 5/31/82 Grant/Contract Closeout Actions Remaining: NONE 7 Final Invoice and Closing Documents Final Fiscal Report n Final Report of Inventions Govt. Property Inventory & Related Certificate Classified Material Certificate n Other Assigned to: EDL/SHD iloboott Laboratory) COPIES TO: Research Administrative Network VirdIrlatiigindiVii Rata Research Security Services EES Public Relations (2) Research Property Management Regats-Cocfdri-gro l floca) Computer Input Accounting Legal Services (OCA) Project File Procurement/EES Supply Services Library Other

3 /e7 SAMPLING AND ANALYTICAL METHODS AVAILABLE FOR COMPLIANCE WITH THE OSHA COTTON DUST STANDARD Prepared for: CENTAUR ASSOCIATES Project ila-3219 GEORGIA INSTITUTE OF TECHNOLOGY Engineering Experiment Station Occupational Safety ac Health Services Atlanta, Georgia (404)

4 SAMPLING AND ANALYTICAL METHODS The sampling instrument selected by OSHA for determining cotton dust levels is the Lumsden-Lynch vertical elutriator (VE). It is calibrated to 7.4 (i- 0.2) liters per minute and positioned 4% to 5/4 feet from the floor in a stationary location within the worksite. The VE is operated for a minimum of six hours of each eighthour shift. OSHA allows the use of alternative samplers provided their readings of workplace dust concentrations are satisfactorily equivalent to the readings of the VE. Alternative samplers must preseparate nonrespirable dust (i.e., aeordynamic equivalent diameter of greater than or equal to 15 microns). Additionally, it must be shown in side-by-side testing in representative workplaces that the alternative sampling method has equivalent performance to the VE in terms of precision and accuracy. The readings of the alternative sampler must be within + 25% of the VE readings, for 95% of the samples in the range of 0.5 to 2 times the permissable exposure limit (i.e., 100 to 400 ug/m 3 in yarn manufacturing). Instrumentation Vertical Elutriators A Lumsden-Lynch VE sampler is a dust sampler which has in theory a particle size cut-off at approximately 15 microns aerodynamic equivalent diameter when operating at the flow rate of 7.4 (± 0.2) liters per minute (Ipm). The separation chamber of the elutriator has an inside diameter of 6.0 inches and a length of 14 inches. The 7.4 1pm flow rate and 6.0 inch inside diameter yield an upward air flow velocity in the separation chamber equal to the sedimentation velocity of a particle with an aeordynamic diameter of 15 microns. Thus, cotton dust particles

5 larger than 15 microns should settle out and not be carried into the 37mm diameter, 5 micron pore size, polyvinyl chloride (PVC) filter which is mounted open-faced and sealed in an inverted position in the exit ferrule of the VE. The 37mm PVC membrane filter is positioned in a three-piece cassette constructed of polystyrene Care is taken to assure that the elements of the cassette have been adequately sealed (using a shrink band). A support pad, commonly called a backup pad, is used under the filter membrane in the field monitor cassette. The filter is weighed before and after sampling in a control environment using a balance sensitive to 10 micrograms. The mass concentration of cotton dust (micrograms per cubic meter) is the collected mass (micrograms) of cotton dust divided by the sampled air volume in cubic meters. Tubing carries the air flow from the filter cassette to the sampler pump. The samplers are calibrated both before they are used in the field and after they are used to assure a flow rate of 7.4 (+ 0.2) 1pm. The calibration is performed with a primary standard such as a wet test meter, or a large bubble meter. The two main manufacturers of VE sampling systems are Sierra Instruments, Inc. and General Metal Works, Inc. (GMW). Both companies market models that are portable and can be either floor or wall-mounted. One difference between the two samplers is that the Sierra samplers use a constant flow controller to maintain a constant sampling flow rate while the GMW uses a critical orifice. The GMW is powered by either 115 volt or 230 volt AC current, depending on the model. There are Sierra models available that will operate on AC current, as well as others that run on 12 volt DC batteries. Additionally, both manufacturers offer various optional equipment. Alternative Samplers As stated previously, alternative samplers to the VE are acceptable for meeting the monitoring requirements of the standards, as long as they can

6 demonstrate equivalency to the VE. There are four manufacturers of equipment which may serve as an alternative sampler: ppm, Inc.; TSI, Inc.; GCA Corporation; and MDA Scientific Inc. It is possible that there are other manufacturers of equipment that may qualify as alternative samplers. To date, the only manufacturer known to have had equipment accepted by OSHA as an alternative sampler to the VE is ppm, Inc. All of these instruments are less cumbersome to handle than the VE and each manufacturer has a portable self-contained model. In addition, they all have direct reading capabilities. All of these items are important considerations when one considers the labor-intensive requirements of monitoring workplaces with the VE. Two types of continuous aerosol monitors are manufactured by ppm, Inc.; however, the methods for both are identical. They are the CAM (Continuous Aerosol Monitor) and the PCAM (Portable Continuous Aerosol Monitor). PCAM is a portable, single sensor version of the multisensor CAM system and both use a halfscale vertical elutriator. Simply described, its operation is a continuous electrooptical weighing of the effluent of the half-scale VE. Dust concentration data from each of the sensors (up to 16) are quickly computed in a microprocessor-based control/readout unit. This is an electro-optical method based on near-forward light scattering which combines the principles of photometry and single particle counting and uses a microprocessor to produce mass concentration readings of workplace or process aerosol concentrations. An air line (umbilical) connecting the sampler to the control/readout draws air at a flow rate of 2.0 liters/minute through an aerodynamic preseparator (half-scale vertical elutriator), past the sensor and into the umbilical tubing. Approximately once every hour the system is purged by reversing the air flow in the tubing to clean the internal parts of the CAM sensor and the vertical elutriator and to establish a zero baseline with clean air. The calibration is also checked automatically during the two minute purge cycle period.

7 A solid state microprocessor controls the readout of data and is programmed to convert the signals generated by each sensor into micrograms per cubic meter. The measurement time for the cotton dust level to be determined by the sensor is less than a millisecond. The control readout is expressed instantaneously as a visual display and recorded on a periodic printout. This printout gives the timeweighed average dust level during the sample period for each sensor location. The averaging or printout interval is adjustable in periods ranging from 15 minutes to 24 hours. The operation of this CAM sensor measures scattered light from the particles in the air stream after passing through the half-scale vertical elutriator. Particles within the sensing chamber scatter radiation into the collection optics and to a detector. The signal generated at the detector is electronically converted by the microprocessor into a reading proportional to the weight of the particles. The signal is proportional to the mass of the particles per unit volume. The microprocessor also permits automatic compensation of baseline zero and calibration. The CAM instrument is reported to be insensitive to flow rate, pressure, temperature, or gas composition of the sample fluid. TSI, Inc. manufacturers a number of particle technology instruments. Their TSI model 3500 Piezobalance Respirable Aerosol Monitor with a miniature VE has been used for comparative sampling to the standard VE. It is a portable selfcontained instrument which measures the mass concentration of respirable aerosols (smoke, dust, and fumes). The sample is drawn through the small-scale VE that removes particles with an aerodynamic diameter greater than 15 microns. The flow rate is 1.0 Ipm. The sampling crystal is a collecting surface of an electrostatic precipitator that ensures that all aerosol particles are efficiently collected on the quartz crystal sensor. The instrument measures mass concentration by the frequency change of

8 the oscillating quartz crystal. A second crystal, not exposed to the aerosol, corrects for frequency change due to temperature, pressure and humidity changes. The instrument has a measuring time of 24 seconds for high concentrations (1-10 mg/m 3) and two minutes for low concentrations (0.01 to 2 mg/m 3). GCA Corporation also manufacturers a variety of instruments that can be used for on-the-spot measurements of dust levels. The GCA Model RDM-101 Respirable Dust Monitor is commonly used in the textile industry. It is a portable and fully self-contained monitor with automatic and direct digital readout of the mass concentration of airborne dust. It uses a two-stage collection system operating at a flow rate of two liters per minute. The first stage consists of a miniature VE (sized for an aerodynamic separation of spherical particles greater than 15 microns). Particles that pass through the preseparator are collected by the second stage of the instrument. The second stage consists of a circular nozzle impactor-beta absorption assembly with a manually operated indexing, polyester impaction disc. The dust collected by impaction on the thin plastic fiber absorbs the betaradiation from a carbon-14 source reaching a Geiger detector. The mass of dust collected is determined by the attenuation of beta-radiation which takes place after the sampling mode. The electronic programming and computing circuit of the instrument provides the operator with a direct readout in units of mass concentration. A continuous, unattended single or multipoint monitoring system is also manufactured by GCA. It is the Model RAM-S, Real-Time Aerosol Sensor. This is a compact, self-contained line operated instrument capable of measuring aerosol concentrations over a range of 5 ug/m 3 to 200 ug/m 3. Its detection configuration consists of a pulsed light-emitting diode in combination with a silicon detector which senses the light scattered over a forward angle of 45 to 95 by the particles

9 traversing the sensing volume. Synchronous phase-sensitive electronic amplication of the signal provides extremely stable operation with an analog output directly proportional to the aerosol concentration. The flowrate (normally adjusted to 2 liters per minute) is maintained constant by means of an automatic controller. A VE attachment is available to be used as a precollector for cotton dust monitoring. Also, it can be operated as part of a sensing network using a central data logger or a computer. An advanced data logger-multipoint recorder-alarm monitor for up to 128 RAM-S sensors is available from GCA (Model DIALOG-3). MDA Scientific, Inc. has two models of aerosol monitors. One the P-5L, is for high dust levels (0.01 to 100 mg/m 3) and the other, the P-5H, is for measuring very low dust levels (0.001 to 10 mg/m 3). Both instruments measure dust from submicron to 10 micron size. This respirable fraction is obtained by drawing the contaminated air through a double impaction separator by an internal fan. The separator also serves as an optical maze to prevent outside light from entering the ilumination chamber. The relative dust concentrations are determined by measuring the intensity of light scattered by the dust passing through the illumination chamber. The greater the intensive of scattered light, the higher the concentration of dust. Normally the models are used with a built-in impactor; however, this can be removed so that it can be used with a miniature VE.

10 MEASUREMENT METHODOLOGY Sampling Sites Sampling sites should be chosen in such a manner as to represent each distinct work area of an employee exposed to cotton dust. The average of these sites, when a time-weighted approach is applied, will be representative of the employee's individual exposure to cotton dust. The selection of the sampling sites will vary from mill to mill, even though the processes may be very similar. This is due to variation in work assignments and differences in production. One approach in selecting sites is to first determine for each employee classification the major duties of the job. The various areas in which the employee will work to complete these duties should be identified and a sampler should be placed in each distinct area. For example, an Opening Room with five opening hoppers lined against one wall has one employee feeding the hoppers. His primary duties are to carry cotton from the open bales lined in front of the hoppers and place the cotton in the hoppers. Occasionally, he is required to "pull a choke" that has formed on the back of the hoppers or perform other maintenance on the conveyor line behind the hoppers. The three main areas where work is performed is the area of the room where the opened bales of cotton lie, the front of the hoppers where the cotton is fed, and the rear of the hoppers where periodic exposure takes place. Depending on the size of the room, as few as three cotton dust samplers could be positioned to determine a representative dust sample. In each area, the sampler would need to be positioned as close to the center of the particular area as practical without needlessly interferring with work. One would be placed in the center of the opened bale area, one adjacent the front of the third hopper, and one adjacent the conveyor line behind the third hopper. All three samplers would be

11 operated simultaneously. It should be noted that depending on the individual room characteristics, air movements, work assignments, blends, etc., this arrangement could vary or more samplers may be required. The main concern in sample site selection should be the representation of employee exposure to cotton dust and not the convenience of the individual conducting the sampling. Although columns and electrical outlets will sometimes coincide with areas desired to be sampled, sampling sites should not be limited to where such conveniences are located. Not only can columns be located in areas that are not the most representative of major work sites but, often, they may be in areas that could have a higher dust, level than the employee is usually exposed to. Such may be the case when columns in the middle - between two opening hoppers or two pickers or two cards - are used, (since the worker may seldom actually work between the two pieces of machinery). In many, if not most cases, this will require that the sampler be capable of being floor mounted. An additional benefit of a floor mounted sampler, is that the stand that supports the sampler is usually much smaller in size than the structural columns oftentimes used to mount a sampler. Consequently, there should be less restriction on the sampling radius. Another approach to determining representive sampling areas has been described by F. M. Shoffer et al. in a paper entitled "Electro-Optical Measurement of Cotton Dust: An Equivalent Alternative to the Vertical Elutriator." The paper was presented at the Third Special Session on Cotton Dust, Beltwide Cotton Conference, Pheonix, Arizona on January 9-10, This method requires the use of a continuous monitoring system. A dense array of sensors is temporarily deployed within a work area for which the most representative few points are desired. The data from all sensors is monitored continuously and frequently. From this data, the correlation coefficient between

12 each of the points and the room or area average can be computed. Preferably, numerous samples, over a wide range of operational conditions, enter into the calculations. Those points which indicate the maximum correlation with the room average may be concluded as the most representative. Since the time that this was first presented, the method has been further refined by Dr. Shofner et al. Time-Weighted Averages After the results of the VE samples has been calculated, the data should be time-weighted to determine an average exposure for the employee. Using the Opening Room example given in the above section on Selection of Sampling Sites, suppose, for example, that the employee spends 30 minutes of his shift behind the hoppers, about 65% of the remainder of the time around the opened bales of cotton and 35% adjacent the front of the hoppers. Also, out of an eight-hour shift approximately 30 minutes is spent out of the area (i.e., outside smoking, going to the breakroom or bathroom, etc.) As a result, the employee has 450 minutes of exposure per eight-hour shift to cotton dust in the Opening Room. Of this time 30 minutes is behind the hoppers, 273 minutes is around the bales lined on the floor, and 147 minutes is adjacent the front of the hoppers. If results were obtained that determined a cotton dust level of 350 ug/m 3 behind the hoppers, 250 ug/m 3 adjacent the hoppers and 150 ug/m 3 adjacent the bales, the following time-weighted calculation would be performed: TWA = 30 min (350 ug/m 3) min (250 ug/m 3) min (150 ug/m 3) + 30 (0) TWA = ug/m3 480 min

13 However, if a straight arithmetic average had been calculated, the exposure would have been 250 ug/m 3. Obvisouly, if the high dust areas are also the areas where the longest exposures take place, the TWA would be weighted to the higher dust levels. Other factors should also be considered when comparing cotton dust sampling data to the PEL. One such factor is the sampling and analytical error (SAE). The SAE takes into account the difference that may exist between measured exposure and the true exposure. The total error is dependent upon the combined effects of the contributing errors inherent in sampling analysis, and pump flow. In general, SAE are developed to provide a 95% confidence limit. Apparently, an SAE has not been determined for vertical elutriator sampling. The only reference to a factor that could be found in the literature was stated by Burlington Industries in their "CAM/LVE Equivalency Demonstration" paper. They reported that it has been their observation that "experienced" sampling teams will generally obtain readings using the VE with a coefficient of variation (C. V.) of perhaps 10%. Less-experienced teams, will of course produce both a bias as well as a larger ramdom scatter or coefficient of variation. Consequently, since no SAE has been found, it is thought that this 10% C. V. should be applied in the determination of confidence limits for the average exposure estimates from samples.