Cotton dust air sampling procedures

Place samplers in locations that accurately reflect the air a worker breathes in each distinct work area, at breathing-zone height (about 4½ to 5½ feet above the floor). The appendix says to collect a sufficient number of 6-hour area samples in each distinct work area at locations that provide representative samples of air to which workers are exposed; see Appendix A to 1910.1043.

• Put the inlet about 4½ to 5½ feet from the floor (breathing-zone height) as recommended in the sampling procedure.
• Sample simultaneously or sequentially during a normal operating period to capture typical exposures.
• Choose sampling points that reflect different tasks, machines, or ventilation patterns within the work area.

Reference: Appendix A to 1910.1043.

Compute the TWA by weighting the concentration in each location by the hours the worker spent there and dividing by the total hours exposed. The appendix gives this formula: sum (hours in each location × dust concentration in that location) ÷ total hours exposed; see Appendix A to 1910.1043.

• Record each location, the measured concentration for that location, and the hours the worker spent there.
• Keep the computed TWA logged and maintain it on file for review as instructed in the appendix.

Reference: Appendix A to 1910.1043.

Use the Lumsden-Lynch vertical elutriator operating at 7.4 ± 0.2 liters per minute. The appendix specifies that the selected instrument is the Lumsden-Lynch vertical elutriator and that it should operate at a flow rate of 7.4±0.2 L/min; see Appendix A to 1910.1043.

• Monitor pumps during sampling and clean samplers prior to use.
• If dusty conditions risk filter overloading, the appendix allows shorter sampling times to avoid overloading.

Reference: Appendix A to 1910.1043.

Use a three-piece polystyrene 37-mm cassette with a 37-mm polyvinyl chloride (PVC) membrane filter of 5 µm pore size and a support (backup) pad under the filter. The appendix specifies a three-piece cassette constructed of polystyrene and PVC membrane filters with 5 µm pore size and 37-mm diameter; see Appendix A to 1910.1043.

• Ensure an adequate seal between cassette parts to prevent leaks.
• Use a support pad under the filter as called for in the appendix.

Reference: Appendix A to 1910.1043.

Use a balance sensitive to 10 micrograms for weighing filters. The appendix requires a balance with sensitivity to 10 µg; see Appendix A to 1910.1043.

• Tare and zero the balance before each weighing session.
• Keep weighing logs that match cassette numbers to filter weights for chain-of-custody and quality control.

Reference: Appendix A to 1910.1043.

Calibrate samplers when first received, after repair or abuse, and both before and after heavy field use using a primary standard such as a spirometer, wet test meter, large bubble meter, or dry gas meter. The appendix instructs that samplers shall be calibrated at those times and recommends a primary standard for calibration, with detailed wet test meter steps provided; see Appendix A to 1910.1043.

• Follow the wet test meter steps: level the meter, run it 30 minutes before calibration, assemble the sampling train, operate 10 minutes before starting calibration, record start/stop readings, and calculate flow.
• Record wet test meter serial number, person performing calibration, orifice number, pressure drop, air temperature, barometric pressure, and flow rate on calibration data sheets.

Reference: Appendix A to 1910.1043.

You must ensure the wet test meter water level touches the calibration point, let the meter run 30 minutes before calibration, operate the system 10 minutes before starting the calibration, and record meter start/finish readings and elapsed time. The appendix lists these wet test meter procedures and the calibration data that must be recorded; see Appendix A to 1910.1043.

• Confirm water temperature is 1–2 °F warmer than room temperature if adding water.
• Record readings, elapsed time (at least two minutes), pressure drop, air temperature, barometric pressure, and orifice number.

Reference: Appendix A to 1910.1043.

Ensure the manometer pressure drop across the orifice does not exceed 1.0 inch of water during calibration checks, and the pump vacuum gauge reads above 17 inches of mercury when the sampler is running. The appendix requires a pressure drop no greater than 1.0 inch of water across the wet test meter during calibration and that the vacuum exceed 17 in. Hg during operation; see Appendix A to 1910.1043.

• If pressure drop is greater than 1.0 inch of water, disconnect and check the system before proceeding.
• Verify the pump vacuum exceeds 17 in. Hg before recording starting time for field samples.

Reference: Appendix A to 1910.1043.

Log the sample date/time, sampler and cassette serial numbers, start/stop times and duration, filter weights before and after sampling, dust weight (control-corrected), dust concentration, location, sampler operator name, and any other pertinent information. The appendix lists a specific sampling data log that must include these items; see Appendix A to 1910.1043.

• Use cassette numbers to link field logs to lab results.
• Keep records and TWAs as required for review and quality assurance.

Reference: Appendix A to 1910.1043.

Loosely assemble the three-piece cassette, number it, place the absorbent (backup) pad, weigh and place the filter, fully assemble and press parts tightly together, install top and bottom plugs, and apply a shrink band over the joint; then let the shrink band dry. The appendix provides these step-by-step cassette assembly instructions; see Appendix A to 1910.1043.

• Record the pre-sample filter weight (to 10 µg) against the cassette number in the log.
• Keep assembled cassettes aside until the shrink band dries thoroughly to preserve the seal.

Reference: Appendix A to 1910.1043.

Clean the elutriator and motor, install the elutriator at breathing-zone height, mount the cassette, tape it airtight to the ferrule, attach the hose with the critical orifice, start the pump ensuring vacuum >17 in. Hg, and record start time and unit IDs. The appendix gives these field collection steps in order; see Appendix A to 1910.1043.

• Remove the top section of the cassette to install, then replace it and tape the joint for an airtight seal.
• At the end of the sampling period stop the pump and record stop time and sampling duration.

Reference: Appendix A to 1910.1043.

Include two control (blank) filter cassettes with each batch that are handled identically to samples except they are not opened; weigh them with the samples to detect handling contamination. The appendix instructs using two control cassettes per batch to check handling procedures and to investigate any weight differences; see Appendix A to 1910.1043.

• Any weight change in control filters signals possible handling contamination and requires evaluation and corrective action.
• Keep control results with sample logs to document quality control.

Reference: Appendix A to 1910.1043.

Ship the cassette samples along with the appropriate number of blank controls in a suitable container that prevents damage or breakage during transit. The appendix states that samples and blanks should be shipped in a protective container to the analytical laboratory; see Appendix A to 1910.1043.

• Use rigid boxes and padding to prevent jostling and crushing.
• Maintain chain-of-custody records and include sampling logs with the shipment.

Reference: Appendix A to 1910.1043.

Remove the shrink band, open the cassette, remove and weigh the filter to 10 µg accuracy, record the post-sample weight, subtract the clean filter weight and apply any control (blank) correction to get the actual dust mass. The appendix specifies these weighing and correction steps; see Appendix A to 1910.1043.

• Record the post-sample weight against the cassette number in the log.
• If control blanks show weight changes, investigate and apply corrections or recollect samples as needed.

Reference: Appendix A to 1910.1043.

Calculate air volume by multiplying sampling time in minutes by the flow rate in liters per minute and dividing by 1,000 to convert liters to cubic meters. The appendix details this calculation for air quantity in cubic meters; see Appendix A to 1910.1043.

• Use the actual flow rate determined by calibration (e.g., 7.4 ± 0.2 L/min or the orifice-calculated flow).
• Example: a 360-minute sample at 7.4 L/min = (360 × 7.4)/1000 = 2.664 m³.

Reference: Appendix A to 1910.1043.

Subtract the clean filter weight from the dirty filter weight, apply control blank correction to get the sample mass in µg, then divide that mass by the sampled air volume in cubic meters to obtain µg/m³. The appendix gives this step-by-step method for calculating dust concentration; see Appendix A to 1910.1043.

• Record both the mass (µg) and air volume (m³) in the log and note the final concentration.
• Keep calculations and raw data for review and quality assurance.

Reference: Appendix A to 1910.1043.

Shorten the sampling time to avoid filter overloading and still collect representative samples; the appendix allows shortened sampling times in dusty areas to prevent overloading. The appendix explicitly permits shortening sampling time when dusty conditions would overload the filter; see Appendix A to 1910.1043.

• Note the shortened duration and reason on the sampling log.
• If many shortened samples are needed, consider additional replicate samples or alternative sampling locations to ensure representative data.

Reference: Appendix A to 1910.1043.

Yes — monitoring equipment used in Class III hazardous locations must be approved for such locations according to OSHA electrical standards in Subpart S of part 1910. The appendix requires that monitoring equipment for use in Class III hazardous locations be approved in accordance with 1910 Subpart S; see Appendix A to 1910.1043.

• Confirm the pump and any electrical components carry the proper approvals for the hazardous class.
• Consult the OSHA electrical standards in 1910 Subpart S for specific approval requirements.

Reference: Appendix A to 1910.1043 and 1910 Subpart S.

At start-up, confirm the pump vacuum gauge reads above 17 in. Hg, record starting time and instrument IDs, and monitor pumps during sampling to ensure consistent flow. The appendix instructs checking the vacuum gauge (>17 in. Hg) before recording start time and monitoring pumps during sampling; see Appendix A to 1910.1043.

• Record cassette and sampler serial numbers and start/stop times in the log.
• If pump performance changes during sampling, stop and document the problem; re-sample if necessary to maintain data integrity.

Reference: Appendix A to 1910.1043.

Number each cassette, record that cassette number on the sampling log along with sampler serial number, start/stop times, and filter weights so you can trace each filter to its field records. The appendix requires numbering cassettes and recording identification details in the sampling data sheets; see Appendix A to 1910.1043.

• Use permanent, legible labeling and keep the cassette number on all related records and on the shrink band.
• Maintain chain-of-custody from field to lab to reporting.

Reference: Appendix A to 1910.1043.

Record wet test meter start/finish readings, elapsed time (at least two minutes), pressure drop at the manometer, air temperature, barometric pressure, limiting orifice number, flow rate, calibrator serial number, person performing the calibration, and date. The appendix lists these specific calibration data items that must be recorded; see Appendix A to 1910.1043.

• If flow is within 7.4 ± 0.2 L/min, perform a second calibration and average results, noting the orifice number.
• If flow is out of limits, change or discard the orifice and repeat the calibration.

Reference: Appendix A to 1910.1043.

Yes — clean lint out of the motor and elutriator before sampling to avoid sample contamination and to ensure proper operation. The appendix directs cleaning lint from the motor and elutriator as part of the sampling collection steps; see Appendix A to 1910.1043.

• Regular cleaning helps prevent pressure-drop problems and reduces the chance of false high weights due to non-sample debris.
• Maintain pump and elutriator maintenance records as part of quality assurance.

Reference: Appendix A to 1910.1043.

If control blanks show any weight change, evaluate the handling and weighing procedures, determine the cause, make necessary corrections, and consider collecting additional samples. The appendix states that differences in blank filter weights indicate handling problems and require evaluation to ascertain cause and corrective action; see Appendix A to 1910.1043.

• Document the investigation, corrective steps taken, and whether additional sampling was performed.
• Keep this documentation with the sampling logs for review.

Reference: Appendix A to 1910.1043.

Yes — you may shorten sampling times in very dusty locations to avoid filter overload, but you must note the shortened durations and ensure samples remain representative for comparison. The appendix allows shortening sampling time to avoid overloading while also recommending simultaneous or sequential collection during normal operating periods to obtain representative samples; see Appendix A to 1910.1043.

• When sampling times differ, normalize concentrations by calculating the actual mass per cubic meter using the measured air volumes so results are comparable.
• Record the reason for shortening and maintain documentation for data interpretation.

Reference: Appendix A to 1910.1043.