California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 4 - Construction Safety Orders › Article 4 - Dusts, Fumes, Mists, Vapors, and Gases › Appendix A - OSHA Reference Method Mandatory

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
This mandatory appendix specifies the procedure for
						analyzing air samples for asbestos and specifies quality control procedures
						that must be implemented by laboratories performing the analysis. The sampling
						and analytical methods described below represent the elements of the available
						monitoring methods (such as appendix B to this section, the most current
						version of the OSHA method ID-160, or the most current version of the NIOSH
						7400 method) which OSHA considers to be essential to achieve adequate employee
						exposure monitoring while allowing employers to use methods that are already
						established within their organizations. All employers who are required to
						conduct air monitoring under subsection (f) of this section are required to
						utilize analytical laboratories that use this procedure, or an equivalent
						method, for collecting and analyzing samples.
Sampling and Analytical Procedure
1. The sampling medium for air samples shall be mixed
						cellulose ester filter membranes. These shall be designated by the manufacturer
						as suitable for asbestos counting. See below for rejection of blanks.
2. The preferred collection device shall be the 25-mm
						diameter cassette with an open-faced 50-mm extension cowl. The 37-mm cassette
						may be used if necessary but only if written justification for the need to use
						the 37-mm filter cassette accompanies the sample results in the employee's
						exposure monitoring record. Do not reuse or reload cassettes for asbestos
						sample collection.
3. An air flow rate between 0.5 liter/min and 2.5
						liters/min shall be selected for the 25-mm cassette. If the 37-mm cassette is
						used, an air flow rate between 1 liter/min and 2.5 liters/min shall be
						selected.
4. Where possible, a sufficient air volume for each air
						sample shall be collected to yield between 100 and 1,300 fibers per square
						millimeter on the membrane filter. If a filter darkens in appearance or if
						loose dust is seen on the filter, a second sample shall be started.
5. Ship the samples in a rigid container with sufficient
						packing material to prevent dislodging the collected fibers. Packing material
						that has a high electrostatic charge on its surface (e.g., expanded
						polystyrene) cannot be used because such material can cause loss of fibers to
						the sides of the cassette.
6. Calibrate each personal sampling pump before and after
						use with a representative filter cassette installed between the pump and the
						calibration devices.
7. Personal samples shall be taken in the "breathing
						zone" of the employee (i.e., attached to or near the collar or lapel near the
						worker's face).
8. Fiber counts shall be made by positive phase contrast
						using a microscope with an 8 to 10 X eyepiece and a 40 to 45 X objective for a
						total magnification of approximately 400 X and a numerical aperture of 0.65 to
						0.75. The microscope shall also be fitted with a green or blue filter.
9. The microscope shall be fitted with a Walton-Beckett
						eyepiece graticule calibrated for a field diameter of 100 micrometers (+/- 2
						micrometers).
10. The phase-shift detection limit of the microscope
						shall be about 3 degrees measured using the HSE phase shift test slide as
						outlined below.
a. Place the test slide on the microscope stage and
						center it under the phase objective.
b. Bring the blocks of grooved lines into focus.
Note:
The slide consists of seven sets of
						grooved lines (ca. 20 grooves to each block) in descending order of visibility
						from sets 1 to 7, seven being the least visible. The requirements for asbestos
						counting are that the microscope optics must resolve the grooved lines in set 3
						completely, although they may appear somewhat faint, and that the grooved lines
						in sets 6 and 7 must be invisible. Sets 4 and 5 must be at least partially
						visible but may vary slightly in visibility between microscopes. A microscope
						that fails to meet these requirements has either too low or too high a
						resolution to be used for asbestos.
c. If the image deteriorates, clean and adjust the
						microscope optics. If the problem persists, consult the microscope
						manufacturer.
11. Each set of samples taken will include 10% field
						blanks or a minimum of 2 field blanks. These blanks must come from the same lot
						as the filters used for sample collection. The field blank results shall be
						averaged and subtracted from the analytical results before reporting. A set
						consists of any sample or group of samples for which an evaluation for this
						standard must be made. Any samples represented by a field blank having a fiber
						count in excess of the detection limit of the method being used shall be
						rejected.
12. The samples shall be mounted by the acetone/triacetin
						method or a method with an equivalent index of refraction and similar
						clarity.
13. Observe the following counting rules.
a. Count only fibers equal to or longer than 5
						micrometers. Measure the length of curved fibers along the curve.
b. Count all particles as asbestos that have a
						length-to-width ratio (aspect ratio) of 3:1 or greater.
c. Fibers lying entirely within the boundary of the
						Walton-Beckett graticule field shall receive a count of 1. Fibers crossing the
						boundary once, having one end within the circle, shall receive the count of one
						half ( ½ ). Do not count any fiber that crosses the graticule boundary
						more than once. Reject and do not count any other fibers even though they may
						be visible outside the graticule area.
d. Count bundles of fibers as one fiber unless individual
						fibers can be identified by observing both ends of an individual fiber.
e. Count enough graticule fields to yield 100 fibers.
						Count a minimum of 20 fields; stop counting at 100 fields regardless of fiber
						count.
14. Blind recounts shall be conducted at the rate of 10
						percent.
Quality Control Procedures
1. Intra-laboratory program. Each laboratory and/or each
						company with more than one microscopist counting slides shall establish a
						statistically designed quality assurance program involving blind recounts and
						comparisons between microscopists to monitor the variability of counting by
						each microscopist and between microscopists. In a company with more than one
						laboratory, the program shall include all laboratories and shall also evaluate
						the laboratory-to-laboratory variability.
2. a. Interlaboratory program. Each laboratory analyzing
						asbestos samples for compliance determination shall implement an
						interlaboratory quality assurance program that as a minimum includes
						participation of at least two other independent laboratories. Each laboratory
						shall participate in round robin testing at least once every 6 months with at
						least all the other laboratories in its interlaboratory quality assurance
						group. Each laboratory shall submit slides typical of its own work load for use
						in this program. The round robin shall be designed and results analyzed using
						appropriate statistical methodology.
b. All laboratories should participate in a national
						sample testing scheme such as the Proficiency Analytical Testing Program (PAT),
						the Asbestos Registry sponsored by the American Industrial Hygiene Association
						(AIHA).
3. All individuals performing asbestos analysis must have
						taken the NIOSH course for sampling and evaluating airborne asbestos dust or an
						equivalent course.
4. When the use of different microscopes contributes to
						differences between counters and laboratories, the effect of the different
						microscopes shall be evaluated and the microscopes shall be replaced, as
						necessary.
5. Current results of these quality assurance programs
						shall be posted in each laboratory to keep the microscopists
						informed.
1. New
						Appendix A to section
						1529 filed 2-15-91; operative
						2-15-91 pursuant to Government Code section
						11346.2(d)
						(Register 91, No. 19).
2. Editorial correction of HISTORY 1.
						(Register 91, No. 45).
3. Amendment filed 5-3-96; operative 7-3-96
						(Register 96, No. 18).
4. Change without regulatory effect amending
						first paragraph filed 3-26-2020, pursuant to section
						100, title 1, California Code of
						Regulations (Register 2020, No. 13).
Note: Authority cited: Section
						  142.3, Labor
						  Code. Reference: Section
						  142.3, Labor
						  Code.