D. GENERAL CONSIDERATIONS FOR SAMPLING AIRBORNE CONTAMINANTS
by Charles S. McCammon, Ph.D., CIH, NIOSH/Denver Field Office and Mary Lynn Woebkenberg, Ph.D., NIOSH/DPSE
| Contents: | Page | |
|---|---|---|
| 1. | Choosing Measurement Methods and Sampling Media | 17 |
| 2. | Figuring Sampling Parameters | 22 |
| a. | Sampling for Gases and Vapors Using Solid Sorbents | 22 |
| b. | Pushing a Method to the Limit, Limit of Quantitation | 23 |
| c. | Sampling for Dusts Using a Membrane Filter | 24 |
| 3. | Bulk Samples | 24 |
| a. | Bulk Air Samples | 24 |
| b. | Bulk Liquids and Solids | 25 |
| 4. | Blanks | 26 |
| 5. | Direct-Reading Methods | 26 |
| 6. | Sampling Strategy | 27 |
| 7. | Sampling and Calibration Techniques | 27 |
| a. | Calibration of Personal Sampling Pumps | 27 |
| b. | Sampling Instructions for Solid Sorbent Tube Sampler | 30 |
| c. | Sampling Instructions for Filter Sampler | 31 |
| d. | Sampling Instructions for Filter + Cyclone Sampler | 32 |
| e. | Jarless Method of Calibration of Cyclone Assemblies | 33 |
| 8. | References | 34 |
1. CHOOSING MEASUREMENT METHODS AND SAMPLING MEDIA
Proper advance planning minimizes sampling and measurement costs and labor and contributes to a smooth, successful survey. Many things must be considered before collecting field samples [1]. The first step is to define sampling objectives. These may include documenting exposures in particular work settings, determining compliance/non-compliance with existing Federal or local standards or recommended exposure limits, or trying to determine the source of a problem. Sampling parameters that should be defined might include type of sample (area vs. personal), contaminant(s) to be sampled, duration of samples, potential interferences and expected contaminant concentrations (or contaminant concentration of interest). Once these parameters are defined, then the proper analytical method and sampling media can be selected. Other general information needed to plan a survey properly include the number of employees, the sampling strategy plan (discussed later), process flow diagram, material safety data sheets on all process materials, the physical states of the substances to be sampled, and potential hazards involved in collecting and shipping the samples.
An accredited analytical laboratory should be used to conduct analysis of collected samples, and it is essential to consult with the analytical laboratory before sampling to ensure that the measurement methods available can meet the defined sampling needs. This step should be an early part of survey planning. The laboratory can also assist in choosing sampling media
