#CAL OSHA BREATHING ZONE PLUS#

Instead of using backup pads, blank acid-treated filters were used as backups in each cassette.

A retention efficiency study was performed by drawing 100 L of air (80% relative humidity) at 1 L/min through sample filters that had been spiked with 0.814 µg MDA. Record sample volumes (in L of air) for each sample, along with any potential interferences. Blanks should be handled in the same manner as samples, but no air is drawn through them. Submit at least one blank filter with each sample set. At some convenient time within 10 hours of sampling, transfer the sample filters to vials. After sampling, seal the cassettes with plastic plugs until the filters are transferred to the vials containing deionized water. Attach the cassette to the sampling pump with flexible tubing and place the cassette in the employee's breathing zone. Immediately before sampling, remove the plastic plugs from the filter cassettes. Deionized water is needed for addition to the vials. Small glass scintillation vials with caps containing Teflon liners are recommended. The vials must be sealable and capable of holding at least 7 mL of liquid. The water can be added before or after the filters are transferred. The cassettes are sealed with shrink bands and the ends are plugged with plastic plugs.Īfter sampling, the filters are carefully removed from the cassettes and individually transferred to small vials containing approximately 2 mL deionized water.

(0.26 N H 2S0 4 can be prepared by diluting 1.5 mL of 36N H 250 4 to 200 mL with deionized water.) The filters are dried in an oven at 100 degrees C for one hour and then assembled into two-piece 37 mm polystyrene cassettes with backup pads. The filters are prepared by soaking each filter with 0.5 mL of 0.26N H 2S0 4. Samples are collected on 37 mm Gelman type A/E glass fiber filters treated with sulfuric acid. Samples are collected by use of a personal sampling pump that can be calibrated within +5% of the recommended flow rate with the sampling filter in line.

#CAL OSHA BREATHING ZONE PLUS#

The standard requires that the method of monitoring must have an accuracy, to a 95 percent confidence level, of not less than plus or minus 25 percent for the select PEL. The employer, however, has the obligation of selecting any monitoring method which meets the accuracy and precision requirements of the standard under his unique field conditions. The method OSHA currently uses is included below. There are a number of methods available for monitoring employee exposures to MDA. Air samples should be taken in the employee's breathing zone (air that would most nearly represent that inhaled by the employee). The arithmetic average of all such random samples taken on one work shift is an estimate of an employee's average level of exposure for that work shift. Random sampling means that any portion of the work shift has the same chance of being sampled as any other. Short-time interval samples (or grab samples) may also be used to determine average exposure level if a minimum of five measurements are taken in a random manner over the 8-hour work shift. Measurements taken for the purpose of determining employee exposure to MDA are best taken so that the representative average 8-hour exposure may be determined from a single 8-hour sample or two (2) 4-hour samples. Methylenedianiline, Appendix D - Sampling and Analytical Methods for MDA Monitoring and Measurement Procedures

Cal osha breathing zone