Air Sampling Placement
To assess air contaminants more thoroughly, air sampling devices equipped with collection media should be placed at various locations throughout the area.
Introduction to Air Sampling
These samples provide air quality information, and can indicate the presence and concentrations of contaminants over the lifetime of site operations.
Area sampling stations may also include DRIs equipped with recorders and operated as continuous air monitors. Area sampling stations should be placed in the following locations:
- Upwind: Because many hazardous incidents occur near industries or highways that generate air pollutants, samples must be taken upwind of the site, and wherever there are other potential sources of contaminants, to establish background levels of air contaminants.
- Support Zone: Samples must be taken near the command post or other support facilities to ensure they are in fact located in a clean area, and the area remains clean throughout operations at the site.
- Exclusion Zone: The Exclusion Zone presents the greatest risk of exposure to chemicals and requires the most air sampling. The data from these stations should be used to verify selected levels of PPE and to set Exclusion Zone boundaries, as well as to provide a continual record of air contaminants. The location of sampling stations should be based upon:
- hot spots or source areas detected by DRIs,
- types of substances present, and
- potential for airborne contaminants.
- Fenceline/Downwind: Sampling stations should be located downwind from the site to determine whether any air contaminants are migrating from the site. If there are indications of airborne hazards in populated areas, additional samplers should be placed downwind.
Although accurate, the air sampling and laboratory analysis option has two disadvantages: cost and time. Analyzing large numbers of samples in laboratories is expensive, especially when results are needed quickly.
Air Sampling Equipment and Media
Sampling systems typically include a calibrated air sampling pump that draws air into selected collection media. Some of the most common types of sampling and collection media are described below:
- Organic Vapors: Activated carbon is an excellent sorbent for most organic vapors.
- Inorganic Gases: The inorganic gases present at a site would primarily be polar compounds such as the haloacid gases and ammonia. These gases can be adsorbed onto silica gel tubes and analyzed by ion chromatography.
- Aerosols: Aerosols (solid or liquid particulates) include soil particles, heavy-metal particulates, pesticide dusts, and droplets of organic or inorganic liquids. An effective method for sampling these materials is to collect them on a particulate filter, such as a glass fiber or mixed cellulose ester fiber membrane.
Knowledge Check Choose the best answer for the question.
4-9. Which zone presents the greatest risk of exposure to chemicals and requires the most air sampling?
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