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heavily loaded surfaces. The sample preparation step increased the homogeneity of subsamples for analysis, which reduced analytical variability and dispersed obstructing debris particles.
􏰀 The wet wipe sampling method allowed composite samples to be collected, with each composite sample representing the result for 3–5 individual surfaces. Composite samples increased the probability of detecting wild􏰁re smo􏰂e residues, resulted in a better characteri􏰃ation of the space that was sampled, and reduced sampling cost by allowing more surfaces to be sampled using fewer samples.
􏰀 Char was the primary wild􏰁re smo􏰂e residue based on the frequency of detection and was most useful in evaluating both exposure of the structures and the impact of wild􏰁re smo􏰂e residues. The frequencies of detection for ash and soot were too low to be useful for assessing impact.
􏰀 􏰄ach of the 􏰁ve similar sampling areas was an independent similar impact area; caution should be used when extrapolating char concentrations between sampling areas to evaluate impact.
􏰀 􏰅ouses closest to the wild􏰁re were impacted by char to a greater extent than those farther from the wild􏰁re. 􏰆bout 􏰇5􏰈 of the interior surface samples with a char concentration of 􏰉􏰈 or more were collected within one mile of the wild􏰁re. 􏰆bout 􏰊􏰋􏰈 of the exterior surface samples were collected within one mile of the wild􏰁re.
􏰀 Theresultsofthestudysuggestedthatmorethanhalf 􏰌55􏰈􏰍 of char concentrations on interior surfaces may be expected to be less than 3􏰈. Therefore, using a char concentration of 􏰎􏰉􏰈 or more􏰏 for wet􏰐 wipe samples as the minimum char concentration for assessing impact was reasonable for the houses included in this study, and was consistent with the laboratory 􏰑􏰒􏰓.
􏰀 The results of the study suggested that the char concentration measured for one of the 􏰁ve sampling areas should not be used to evaluate the impact of char for other sampling areas. Each similar sampling location should be evaluated independently. Char concentrations on interior surfaces were primarily 􏰔􏰉􏰈, 􏰉􏰈􏰐􏰕􏰈, 3􏰈􏰐􏰉􏰖􏰈, and 􏰗􏰉􏰖􏰈.
LIMITATIONS
This was a relatively large study, but just one study. Additional studies should be performed to validate these results and to examine these and other factors that may affect evaluation and assessment strategies for wild􏰁re smo􏰂e residues.
The wild􏰁re smo􏰂e residue samples were collected using the wet􏰐wipe sampling method. 􏰘enerali􏰃ing the results and conclusions of this study to other sampling methods should be done with caution.
The replicated study in reference 2 comparing the wet􏰐wipe and tape lift sampling methods for evaluating char concentrations was based on limited sample si􏰃e.
The inspections and sample collection were per􏰐 formed by an environmental company. The objectives, the extent of residue impact characteri􏰃ation, and the distribution of elapsed times may have been different if the inspections had been performed by a restoration
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REFERENCES
1. Spurgeon, J., Seif, F., Mirica, E. (2021). “A comparison of the Wet Wipe and Tape Lift methods for Sampling Surface Char in Residential Properties Impacted by Wildfire Smoke.” The Journal of Cleaning Science; Fall:16-24.
2. Medina, E. (Ed.). Technical Guide for Wildfire Impact Assess- ment for the Occupational Environmental Health and Safety Professional. AIHA, 2018.
3. Ward, T. (2014). “Evaluating the Use of Indoor Residential Wipe Samples Following a Wildfire.” Intermountain Journal of Sciences; 20(1):1-3.
4. Bari, M.A., Baumbach, G., Kuch, B., Scheffknecht, G. (2009). “Woodsmoke as a source of particle-phase organic com- pounds in residential areas.” Atmospheric Environment; 43(31), 4722–4732.
5. Han, Y.M., Cao, J.J., Lee, S.C., Ho, K.F., An, Z.S. (2010). “Dif- ferent characteristics of char and soot in the atmosphere and their ratio as an indicator for source identification in Xi’an, China.” Atmos. Chem. Phys.; 10, 595–607.
6. Chow, J.C., Watson, J.G. (Aug., 1998). “Guideline on Speci- ated Particulate Monitoring.” Office of Air Quality Planning and Standards (MD-14), U.S. Environmental Protection Agency, Research Triangle Park, NC.
7. Ness, S.A. “Surface and Dermal Monitoring for Toxic Expo- sures” (1994). Van Nostrand Reinhold, New York.
8. ANSI/IICRC S520 Standard for Professional Mold Remediation; Third Edition, December 2015; Institute of Inspection, Cleaning and Restoration Certification, Las Vegas, NV.