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Presenter Bio: Tianbao Bai

Dr. Bai is a certified industrial hygienist (CIH) who received a Ph.D. in Geotechnical Engineering from the University of Illinois at Chicago in 1995. He has over twenty-seven years of experiences in the asbestos, combustion-by-products, and mold lab analysis and broad industrial hygiene consulting practices in asbestos, mold, indoor air quality, lead-based paint, and OSHA compliance monitoring. Dr. Bai currently serves as a member of ASTM D22.07 Subcommittee on Sampling and Analysis of Asbestos and ASTM D22.08 Subcommittee on Sampling and Analysis of Mold, and a member of IICRC/AIHA Section 13 Sub-committee on Analysis, Use, and Interpretation of Data for Wildfire Impact. He also served many years as a member of Analytical Accreditation Board (AAB) and the Technical Advisory Panel (TAP) for AIHA-LAP, LLC.

Presentation Description:

Wildfires in the US have increased significantly during the last two decades, likely due to global warming and the resulting drought conditions, especially in the western part of the US. Wildfires generate combustion-by-products including poisonous gases as well as fine and ultrafine particles including soot, char and ash. Not only are these particles themselves health concerns, their abilities to adsorb other toxic chemicals, such as VOCs, SVOCs and heavy metals, can cause many health problems including respiratory illness, cardiovascular distress, and even increased Covid-19 cases. The fire residues are also corrosive which can damage properties and personal belongings. Therefore, it’s essential to know the indoor concentrations of CBP in structures nearby wildfires for health and insurance claims considerations. Yet to our knowledge there are currently no published CBP concentration data available.

In this study, we evaluated CBP data from over 750 houses in California and Colorado for a total of more than 8000 samples. Samples were collected by consultants using tape lift, wipe and microwave methods, and all samples were analyzed at our laboratory using PLM/RLM following ASTM D6602-13 method for the concentrations of soot, char, and ash. The debris rating on the collected samples were also evaluated based on ASTM D7391-20 method. In addition, anions as well as pH were measured from some wildfire impacted structures to evaluate the corrosivity of the fire residues.

The data of the soot, char, and ash concentration are evaluated statistically and the results from different sampling methods are compared, and the pros and cons of each sampling method are discussed. The relationships between CBP concentrations and anions as well as pH values are evaluated.

The CBP score concept is presented, which is the product of CBP concentration times the debris rating. Based on the CBP score, the combustion-by-products cleaning criteria is proposed.