B-7. Environmental Samples
Control or background samples that are collected from clean samples must be identical to the samples collected from the areas near the attack areas as baseline data. The contaminated samples must be compared to the baseline data (control samples). This is especially true if unknown or nonstandard chemical and/or suspected biological agents were employed. The analysis center uses the control samples to compare with a contaminated one. The recon unit collects control samples of soil, water, and vegetation from areas about 500 meters upwind of an alleged attack area. Control samples generically are the same as those collected in an alleged attack area. For example, if leaves from an apple tree in an attack area were collected as a suspected contaminated sample, the recon team should collect leaves (as a control sample) from an apple tree outside of the contaminated area. If water from a pond in the attack area is collected, the recon unit should collect control samples of water from a pond (not a moving stream) in a nearby clean area. The size of an environmental control sample should be about the same as the suspected contaminated sample collected from the attack area (see [Table B-4], page B-20).
Table B-3. Comparison of Sample Types
| SAMPLE STABILITY | ANALYSIS | |||
|---|---|---|---|---|
| SAMPLE TYPE | INFO VALUE | TO COLLECT | TIME REQUIRED | RELIABILITY |
| AIR | GOOD | GOOD | 20 MIN | HIGH |
| WATER | GOOD | GOOD | 5 MIN | HIGH |
| SOIL | FAIR | FAIR | 5 MIN | MODERATE |
| VEGETATION | FAIR | POOR | 10 MIN | LOW |
| TISSUE | EXCELLENT | FAIR | 30 MIN | HIGH |
| BLOOD | GOOD | FAIR | 10 MIN | HIGH |
| URINE | GOOD | FAIR | 10 MIN | HIGH |
| MUNITION FRAGMENTS | FAIR | FAIR | 10 MIN | FAIR |
| PACKING MATERIALS | FAIR | FAIR | 10 MIN | FAIR |
B-8. Collection of Air and Vapor Samples
a. Air is a good sample matrix since it is a well-mixed medium. Air from a sample site contains a static concentration of contaminants. The concentration of contaminants depends upon the flow rate of the contaminant into the environment, the wind speed, and the physical state of the contaminant, the terrain contours, and temperature as a variable. The sample should be taken within 102 meters of a contaminated surface and at the downwind edge of a contaminated area. The method should consist of pumping a given volume of air, by hand or electric pump, through sample tubes.
b. To avoid contamination, persons conducting air sampling should not use cologne, perfume, insect repellent, medical creams, or strong soaps before taking a sample. The fragrances from these products are volatile organic compounds that may be absorbed on the filter and skew analytical results. Smoke also severely interferes with air sampling, therefore, avoid tobacco and vehicle exhaust smoke.
c. The primary method for collecting air samples is with the PAS 1000 automatic air sampler in conjunction with a TenaxTM tube for a total of three to four minutes when possible. Upon completion of sampling, place the TenaxTM tube in a 2¼-inch piglette. Seal the piglette around the cap with either pressure-sensitive or TeflonTM tape. Once sealed, place the piglette into a Mylar or reclosable bag. Fold the bag around the piglette in a circular motion, then apply another bag and fold again. Once the bag is folded around the piglette, use any type tape to secure the bag around the piglette. Place the piglette into a refrigerator or cooler until the sample is transported to its destination.
d. When chemicals are permitted into the atmosphere from a facility, the best places to obtain samples are close to the emission source where the concentration of the chemical is not diluted. The further from the original point of release, the more diluted the sample becomes from mixing with air, water, or environmental pollutants.