Monitoring Pollutants Inside an Exhibit Case
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Monitoring is the only way to identify the type and amount of pollutants present within an enclosed exhibit case.
When is pollutant monitoring necessary and how do I develop a monitoring program?
In general, pollution levels are monitored to:
- determine the presence of elevated pollutant concentrations;
- identify the concentration of a particular pollutant;
- assess the effectiveness of a control measure.
When planning a monitoring program, it is important to collect relevant information. The location of the monitor and the type of monitor used determines what can be learned from the results. Location to be sampled: The basic approach includes the following:
- 1. monitor the ambient air to determine the general presence of pollutants. (Avoid locating the monitor in pockets of stagnant air unless collection objects are located in the space)
- 2. monitor near a suspected contaminate to evaluate the level of out-gassing;
- 3. monitor next to a sensitive collection to determine whether pollutants are reaching the object's surface. Identification of the specific pollutant(s): Many pollutant monitors are non-specific, reactive tests. More exact methods are required to identify a specific type of pollutant.
Quantities of pollutants: It is often helpful to know the concentration of a pollutant(s) so that an appropriate mitigation strategy can be planned. Some techniques provide no information; other monitors quantify concentrations to varying sensitivities and accuracy. Length of monitoring: One-time monitoring establishes outgassing from new construction or the initial effectiveness of a pollutant mitigation strategy. Continual monitoring of particularly vulnerable collections alerts staff that a pollution control system needs to be replenished.
How can particulate concentrations be measured?
The few commercial products available for monitoring particulate (dust) pollution rely on expensive active sampling. To determine relative amounts of dust in different areas, locate pieces of black paper in the exhibit area or exhibit cases and expose them for preestablished amounts of time. In addition to allowing comparisons to be made, results can be a powerful visual argument for particulate filtration. Some information on particle type and size can be gathered through examination of the collected dust under a transmitted light microscope.
What monitors are available to identify airborne pollutants?
Three types of monitoring products for gaseous pollutants are available. More details on specific products are provided in the following chart.
- Reactive testing indicates if general pollutants are present in a large enough concentration to affect the test matrix (and therefore exhibit material). It does not identify the type of pollutant, its concentration, or whether the pollutant is an actual threat to the collections.
- Passive monitoring techniques are pollutant specific. Many passive monitors developed to test compliance with OSHA human health exposure levels are not sensitive enough to detect the lower levels considered safe for collections. Some products are direct read (diffusion tubes) while others are returned to the manufacturer for analysis (diffusion sampler). These testing methods are most practical for identifying the presence of a pollutant and in determining whether the concentrations have been lowered through a pollution control system.
- Active sampling provides comprehensive, specific and detailed information. A sample of air undergoes complex analysis in a lab. Due to the costs, this sampling technique is generally reserved for critical situations where no contaminate is permissible. Only active sampling can detect very low concentrations of pollutants.
Products, Manufacturers, and Suppliers
Mention of a product, manufacturer, or supplier by name here for information only and does not constitute an endorsement of that product or supplier. Listed materials have been used successfully in past applications. It is suggested that readers also seek alternate product and vendor information to assess the full range of available supplies and equipment.
- Bacharach, Inc., Pittsburgh, PA 15238
- DGA Passive Monitors, DGA Inc., Mountlake Terrace, WA 98043
- Image Permanence Institute, Rochester Institute of Technology, Rochester, NY 14623
- 3M 3500 Monitors, Supplier Lab Safety, Inc. , Janesville, WI 53547
- SKC 575-001 Passive Sampler, SKC West, Fullerton, CA 92831
- Ogawa & Co. USA Inc., Rutherford, NJ 07070