Grantee Research Project Results
2023 Progress Report: Household Atmospheric Dynamics under Elevated Smoke (HADES): Holistic Evaluation of Interventions for Reducing Indoor Levels of Wildland Fire Emissions
EPA Grant Number: R840238Title: Household Atmospheric Dynamics under Elevated Smoke (HADES): Holistic Evaluation of Interventions for Reducing Indoor Levels of Wildland Fire Emissions
Investigators: Gall, Elliott T
Institution: Portland State University
EPA Project Officer: Chung, Serena
Project Period: September 1, 2021 through August 31, 2024
Project Period Covered by this Report: September 1, 2022 through August 31,2023
Project Amount: $547,899
RFA: Interventions and Communication Strategies to Reduce Health Risks of Wildland Fire Smoke Exposures (2021) RFA Text | Recipients Lists
Research Category: Early Career Awards , Air Quality and Air Toxics , Wildfires
Objective:
The Household Atmospheric Dynamics under Elevated Smoke (HADES) project consists of three research objectives that aim to inform our understanding of the transport, removal, and persistence of air pollution generated from wildland fires in indoor spaces. An overarching goal of the project is to enable critical evaluation of interventions that may reduce exposures to smoke indoors.
The first objective consists of a field study in Portland, OR, USA. Here, we will conduct experiments in real buildings to evaluate how changes to building envelopes and mechanical systems affect infiltration and persistence of smoke indoors. Next, in controlled laboratory studies, we will evaluate a wide variety of air cleaning systems. In this study, we will quantify clean air delivery rates (CADRs) under a variety of operating and environmental conditions for particles generated by a wildfire smoke proxy. In addition, we are evaluating if air cleaners can meaningfully remove gaseous organic compounds that are also elevated in smoke and potentially harmful to human health. Finally, we will develop a method to measure the accumulation of persistent organic pollutants on indoor surfaces due to indoor smoke. This study will focus on quantifying the magnitude and retention of polycyclic aromatic hydrocarbons on common indoor materials. Across these interconnected efforts, we aim to inform more accurate modeling of indoor spaces by providing parameterizations of transport and removal processes that are presently not well known. Improved modeling of indoor spaces during fire smoke events will lead to better exposure assessment and epidemiological studies that can account for the protective impact of effective interventions in indoor spaces.
Progress Summary:
Low-cost sensor networks enable measurement of infiltration factors during wildfire smoke periods across building stock. In Year 2, we directed our efforts to prepare for the field study in two ways. First, acknowledging changes to the PurpleAir air monitoring network data warehousing, we contacted PurpleAir to receive read/write keys for their API, developed code in python to access sensors, and have stress tested this code to ensure that we can acquire data flexibly from the PurpleAir database. In parallel, we are further developing our proposed test method to allow estimation of the parameters which underlie the infiltration factor, namely the penetration factor, air change rate, and deposition loss coefficient. To date, there have been no studies that determine these separate parameters for wildfire periods when residents are likely to substantially alter their behavior, building envelope, and use of air cleaning systems.
Commercial and DIY air cleaners can be effective in removing some air pollutants relevant to a regional smoke event. In the past year, we completed a testing matrix of air cleaners. Results include measurement of size-resolved wildfire smoke CADRs (in three size bins), black and brown carbon CADRs, and select VOC CADRs. The test matrix evaluated a comprehensive array of air cleaners that span a range of air cleaning technologies across metrics relevant to wildfire smoke that have not been previously evaluated. We developed a novel method for testing VOC CADRs that accounted for surface sorption in our stainless-steel chamber; we believe this method represents a unique contribution as it allows more rapid testing of VOC decay rates than those methods that require the chamber to reach steady-state conditions during each air cleaner test.
Surface-associated polycyclic aromatic hydrocarbons (PAHs) accumulate during a smoke event, persist for weeks, and can be removed using typical household cleaning processes. Concentrations of PAHs on glass, cotton fabric, and air cleaner filter media were elevated after exposure to a simulated smoke event in the laboratory. Smoke exposed samples have PAHs levels that remain elevated above background for a period of ~40-60 days. Loss of PAHs from the surface implies PAHs are re-emitted to the indoor environment or possibly transformed into byproduct species. In a paper on this topic, we develop a scaling analysis-level calculation of exposure implications for PAHs post-wildfire smoke event. Our calculation indicates that there is potential cause for concern regarding both inhalation and dermal exposure to PAHs following a wildfire smoke event. Fortunately, our study also demonstrated that common cleaning activities can remove meaningful (~50-80%) of PAHs mass from materials.
Future Activities:
Objective 1: The field study will begin in the Spring of 2024 to support a primary study period of the Summer of 2024, aiming to capture infiltration in homes during actual wildfire smoke events. We are testing our method in a controlled chamber environment, analyzing data, and developing models to determine parameterizations automatically. In parallel, we have developed a code to use the PurpleAir API, and continue to analyze low-cost sensor data that is available in increasing numbers of homes that allow direct observation of exposure concentrations during periods of elevated wildfire smoke.
Objective 2: Major milestones on objective 2 are complete. In the following year, we will conduct long-term testing of air cleaners under consistent smoke loading that mimics and long-term smoke event. We will also evaluate CADRs under varying smoke generation conditions and aging, using a newly developed quartz tube furnace smoke generation system.
Objective 3: Objective 3 milestones are complete, and the focus of the project will shift primarily to Objectives 1 and, to a lesser extent, Objective 2 for the subsequent reporting period. We continue to plan subsequent investigations and analytical approaches that will enable better understanding of how wildfire smoke changes indoor surfaces. We have partnered with a PSU analytical laboratory to conduct DART-MS sampling of authentic indoor surfaces to identify PAHs and transformed PAH products due to varying degrees of wildfire smoke.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 5 publications | 1 publications in selected types | All 1 journal articles |
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Type | Citation | ||
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Laguerre A, Gall ET. Measurement of polycyclic aromatic hydrocarbons (PAHs) on indoor materials:method development. ACS Omega 2023;8:20634–41. doi:10.1021/acsomega.3c01184. |
R840238 (2023) |
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Supplemental Keywords:
Indoor air cleaning, filtration, gas-phase air cleaning, PAHs, persistent organic pollutants, exposure, building mechanical systems, building envelopeRelevant Websites:
www.pdx.edu/healthy-buildings Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.