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Delia_Evaluating Fire and Smoke Contamination in Indoor Air

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IAQA 18 th Annual Meeting & Indoor Environment & Energy Exposition, Grapevine TX, 16-18 March 2015 IAQA 18th Annual Meeting & Indoor Environment and Energy Expo (IE3) The views and opinions herein are those of the volunteer authors and may not reflect the views and opinions of IAQA. The information is offered in good faith and believed to be reliable but it is provided without warranty, expressed or implied, as to the merchantability, fitness for a particular purpose or any other matter. Air sampling targets the high to medium volatility compounds and is most applicable within weeks to months after a fire occurs. It will also provide an estimate of the actual inhalation exposure under "normal" conditions. Bulk material sampling targets the medium to low volatility compounds and facilitates an estimate of the potential longer term contamination. Some amount of the gas phase chemical products will be adsorbed by the bulk material and as the concentration of that chemical compound in the air decreases as a result of remediation or natural dilution the bulk material will re-emit that chemical compound into the air, maintaining a low level concentration in the air. Dust sampling is similar to bulk sampling in that it targets the lower volatility compounds that adhere to the dust or condense out of the air. Surface wipe sampling targets the lower volatility compounds that have condensed from the gas phase or were carried by the particulate residue of soot, ash, and char. Since surfaces are likely to be a primary focus of any remediation efforts the selection of sampling location will be critical to ensure the surface is representative of the whole environment and not a recently remediated area. Several factors affect the choice of sample location, sample media, and analysis, including the type and extent of the fire/smoke, the length of time since the fire/smoke event, the environmental conditions, and the extent of cleanup performed. In many indoor air assessments the fire/smoke event occurred months or even years prior to sampling so the focus is often on the less volatile VOCs and sampling may include several media types to encompass all aspects of potential contamination. Data Interpretation There are a number of factors complicating the assessment of data from chemical sampling of air, bulk material, dust, or surfaces subsequent to fire and smoke events. Sources: One of the greatest challenges in evaluating the extent of fire and smoke contamination in indoor air is the number and extent of VOC contributions from sources other than the fire and smoke. Most VOCs have several potential sources so a thorough appraisal of these potential sources is necessary to place the selected fire and smoke VOC indicators into an appropriate context. Volatility: Another key component is the relative volatilities of the indicators. Typically, a more recent fire will produce VOCs spanning the range of high, medium, and low volatilities while only the lower volatility indicators will remain in a situation where the fire occurred some longer period of time previous to the sampling. The higher volatility VOCs will disperse more readily than the lower volatility VOCs, resulting in an unequal distribution over time. This can also be considered the difference between the immediate and persistent indicators.

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