airsampling

Air sampling is the process of collecting samples of air to characterize its contents or properties. It is used to assess occupational exposure to chemicals or dust, monitor environmental air quality, study atmospheric processes, and support regulatory compliance. Samples are typically collected over a defined period and analyzed in a laboratory.

Two broad approaches are used. Active sampling employs a calibrated pump to draw air through a collection medium at a known flow rate, yielding integrated samples over time. Passive sampling relies on diffusion to accumulate contaminants on a sorbent or other medium, without a pump, and is often used for long-term or low-level monitoring. Common media include filters for particulate matter, sorbent tubes or cartridges for volatile or semi-volatile organic compounds, and impingers or condensers for collecting liquids. Sampling can target total particles, size-specific fractions, gases, vapors, or bioaerosols.

Analysis methods vary with the target. Particulates are typically weighed (gravimetric) and may be chemically analyzed to determine composition. VOCs and gases are identified and quantified by chromatography and related detectors. Bioaerosols are assessed by culture methods or molecular techniques such as PCR. Real-time monitors provide instantaneous readings for certain pollutants, while most applications rely on laboratory analysis of collected samples.

Quality control and standards are essential. Calibration of flow meters, use of field and laboratory blanks, sample decontamination, and chain-of-custody procedures ensure data integrity. Limitations include representativeness of the sample, field conditions affecting collection efficiency, and potential loss or alteration of volatile compounds.