Air Sampling Procedures
Air sampling should be conducted using a variety of media and methods to accurately identify the types and concentrations of airborne contaminants present at a site. This process helps determine the extent of contamination and informs decisions regarding appropriate protective measures.
Example Sampling Scenario
Air sampling should follow a structured and methodical approach. The following sampling pattern can be used as a guideline:
- Identify Potential Sources
Begin by visually locating areas or materials that could generate airborne contaminants. - Downwind Sampling
Collect initial air samples downwind from the suspected source along the wind direction axis.
This helps detect contaminants being carried by prevailing winds. - Progress Upwind
Continue sampling upwind toward the source, moving as close as possible while maintaining safety.- During this initial phase, workers should wear Level B protection.
- Protective levels for subsequent sampling can be adjusted based on air monitoring results and the potential for unexpected chemical releases.
- Crosswind Sampling
Once the source or area of highest concentration is reached, collect samples across the wind direction (cross-axis) to determine dispersion patterns.- Smoke plumes or instrument-detectable tracers may be released to visually assess airflow and contaminant spread.
- Upwind Sampling (Background)
Collect upwind air samples to establish background conditions and confirm that detected contaminants originate from the identified source, not from other environmental factors.
Key Considerations
- Use appropriate sampling media (e.g., sorbent tubes, filters, impingers) depending on the contaminant type.
- Document wind speed, direction, temperature, and humidity, as these factors influence sample accuracy.
- Maintain strict chain-of-custody procedures for all samples.
- Review results promptly to adjust protective measures, engineering controls, or work practices as needed.