Presentation Abstracts
Session 1: Tuesday, January 26
Indoor Chemistry on Surfaces
Oxidation of indoor surface materials by ozone and chlorine bleach vapors.
Jon Abbatt, University of Toronto
This talk will present laboratory results on the multiphase chemistry that occurs when gas-phase oxidants are exposed to different reactive molecules found on surfaces, all of which contain double bonds. Ozone is a ubiquitous indoor oxidant, and its chemistry with unsaturated trigylcerides and THC leads to the formation of oxidized organics, such as secondary ozonides, and to gas-phase hydrogen peroxide. Chlorine bleach vapors, largely HOCl, also react with double bonds, forming chlorohydrins. This chemistry occurs with molecules such as squalene and oleic acid, making it likely that we chlorinate our skin oils when we use bleach for cleaning.
Modeling indoor film formation, growth and chemistry.
Pascale Lakey, University of California, Irvine
This talk will present results from two projects focused on kinetic modeling of indoor surfaces. For the first project, we applied a kinetic model to measurements of limonene adsorption on silica surface and demonstrated that model input parameters were consistent with molecular dynamic simulations. For the second project we developed a new model which can treat gas phase boundary layer processes, multi-layer adsorption, bulk diffusion and heterogeneous chemistry. We applied the model to several experimental data sets of multi-layer adsorption as well as running sensitivity tests to determine the impact of gas phase turbulence, bulk diffusion and chemistry on film growth.
Chemical and physical properties of indoor organic films.
Rachel O’Brien, College of William & Mary
Organic films found on indoor surfaces are important locations for chemical reactions and partitioning of semi-volatile organic compounds (SVOCs). For accurate indoor models, we need a better understanding of the chemical composition and viscosity of the complex organic mixtures in these films. This talk will discuss work carried out to probe these properties in films found in indoor spaces like kitchens and living areas.
Session 2:Tuesday, February 23
The Roles of Water and Partitioning in Indoor Chemistry
Indoor partitioning of volatile organic compounds.
Demetrios Pagonis, University of Colorado Boulder
Partitioning to surfaces is a major sink of volatile organic compounds (VOCs) indoors. I will present the results of field and laboratory investigations into the extent, reversibility, and impacts of this partitioning on the concentrations and fate of VOCs indoors. Permeable surfaces, including paint, play a major role in the uptake of indoor VOCs and can significantly limit the extent to which indoor VOC emissions are ventilated to outdoor air.
Surface Water in Indoor Environments: Processes and Impact.
Heather Schwartz-Narbonne, University of Toronto
The high surface area to volume ratio found indoors renders surface chemistry especially important, and the reactivity of these surfaces depends on their physical and chemical makeups. One controlling factor in surface reactivity is the presence or absence of adsorbed water. In this presentation, I will discuss how water adsorbs to these surfaces and the role that it can play in two scenarios: intentionally condensed water on air conditioner cooling coils, and unintentionally adsorbed water on indoor surfaces. On air conditioner cooling coils, condensed water removes water soluble trace gases from the indoor environment. The rate and extent to which these gases are permanently removed is controlled by air conditioner and environmental parameters. Indoor surface films exhibit unique and unexpected water sorptive properties, which depend on the location of the film being sampled. These films contain ions such as nitrate, which can be photolyzed using indoor light sources and TiO2-based indoor paint. The products and efficiency of this photolysis depend on the relative humidity of the test chamber.
Hydrolysis reactions of phthalates and other man-made esters in indoor environments.
V. Faye McNeill, Columbia University
The hydrolysis of phthalates and other man-made esters (MMEs) in the indoor environment may be connected with poor indoor air quality and “sick building syndrome.” We have made laboratory measurements of the hydrolysis kinetics and mechanisms of several MMEs in bulk aqueous solutions under a range of pH conditions, using UPLC-QTOF MS for detection of reactants and products. We have used the laboratory data to refine a numerical model of multiphase chemistry in the indoor environment, based on the McNeill group model GAMMA, that allows us to quantify and predict the impacts of MMEs and MME hydrolysis on indoor air quality under different conditions.
Session 3: Tuesday, March 23
People, Health, and Indoor Chemistry
People Chemistry.
Jonathan Williams, Max Planck Institute for Chemistry
How much do you affect the indoor air chemistry going on around you, just by being present in a room? Afterall human beings are potent mobile sources of chemicals, through breath and skin emissions. In the Sloan sponsored project ICHEAR we have examined chemical emissions from people under controlled conditions and how they vary with temperature, humidity, age, clothing and ozone. Measurements were made at the DTU climate chamber in Copenhagen using groups of four seated individuals. Emissions of volatile organic compounds, OH reactivity, ammonia, carbon dioxide and particles will be discussed.
Wearable passive air samplers for capturing personal exposure to airborne contaminants.
Krystal Pollitt, Yale University
Capturing pollutant exposure at the individual level is critical in advancing our understanding of disease risk factors. Wearable passive samplers are a promising and exciting tool that enable non-invasive assessment of a time-integrated exposure to thousands of chemicals at the individual-level from a range of sources, including consumer products, building materials/furnishings, clothing, diet (food products, additives, contaminants) and pharmaceuticals. I will present results from recent exposure assessment studies that have used wearable passive samplers and discuss opportunities to explore the health impacts of chemical exposures across vulnerable groups in less accessible regions of the world.
Ozone-skin chemistry and lotions.
Glenn Morisson, University of North Carolina, Chapel Hill
Abstract coming soon.
Session 4: Tuesday, April 27
Integrating modeling and measurements indoors
Condensable Organic Material Emissions from HOMEChem Stir-frying: Application of VBS Modeling Techniques.
Michael Waring, Drexel University
Organic aerosol (OA) is emitted indoors, and cooking OA emissions are one of the strongest indoor sources in residences. Cooking OA emissions are usually parameterized by a particle emission rate. However, OA is not a static entity, and it instead is a system of gas and particle concentrations, in a state of dynamic equilibrium, termed here total organic matter (OM). In this framework for OM, thermodynamic absorptive partitioning governs the organic mass in the aerosol phase. Therefore, cooking emissions can instead be considered in terms of OM emitted, rather than OA emitted, and the effective OA particle emission rate from the same OM emission event may vary based on fluctuations in temperature and magnitude of the absorbing OA mass. We developed a methodology that, given measurements of factorized OA concentrations and indoor temperature, back-calculates OM emissions. Our methodology assigns each measured cooking OA factor a volatility basis set (VBS) distribution, which allowed the partitioning strength to be accounted for and OM emission to be computed. We applied our methodology to OA measurements made throughout stir-fry cooking events during the House Observations of Microbial and Environmental Chemistry (HOMEChem) campaign. Results and implications of this approach are discussed.
Combining measurements and models to predict indoor radical concentrations: Effects of non-bleach (hydrogen peroxide) cleaning and indoor lighting conditions.
Shan Zhou, Rice University
Full author list: SHAN ZHOU, Tara F. Kahan, Cora J. Young, Trever C. VandenBoer, Jianshun Zhang, Nicola Carslaw, Zhenlei Liu, Zixu Wang, Beverly B. Guo, Shawn F. Kowal, and Alyssa R. Cregan
The largest uncertainties in quantifying the role of indoor photochemistry on indoor oxidative capacity are the magnitudes of oxidant sources and sinks and the indoor ultraviolet (UV) photon fluxes. This talk will present results from two different studies that address both aspects. We first discuss measurements of the hydroxyl radical (OH) precursor hydrogen peroxide (H2O2) in a simulated room following wiping the floor with an H2O2-based cleaner, complimented by modelled predictions of radical concentrations. This work contributes to an improved understanding of the role of cleaning activities and photochemistry on indoor oxidation capacity. Next, we discuss a measurement campaign designed to constrain indoor UV photon fluxes under different conditions (illumination source, solar angle, window type, distance from source, etc.). We propose mathematical relationships to assist predictions of indoor radical concentrations throughout indoor spaces under changing illumination conditions. This work may provide useful input to indoor chemistry models.
Computational Fluid Dynamics (CFD) Simulations of Indoor Chemistry.
Donghyun Rim, Penn State University
A number of gas-phase species undergo chemical reactions in indoor environments and some reaction products can fluence human health and productivity. In the Sloan-sponsored project MOdelling Consortium for Chemistry of Indoor Environments (MOCCIE), my group studies indoor chemical processes and pollutant dynamics using computational fluid dynamics (CFD) simulations. In this talk, I will discuss oxidation processes and reactive chemistry associated with ozone, nitrous acid (HONO), and chlorine bleach in indoor environments.
Session 5: Tuesday, May 25
Closing Plenary
Indoor Chemistry and Exposure Science.
Charles Weschler, Rutgers University
There are six pollutants for which the US EPA sets National Ambient Air Quality Standards (NAAQS): particulate matter (PM), ozone (O3), carbon monoxide (CO), lead (Pb), sulfur dioxide (SO2), and nitrogen dioxide (NO2). Although the concentration limits are for outdoor air, most of our inhalation of these pollutants occurs indoors. For at least three of these pollutants, chemical transformations occur when the pollutant is transported indoors. PM can lose or acquire water, ammonium nitrate, and various semivolatile organic compounds depending on temperature, relative humidity, and concentration differences between outdoor and indoor air. A substantial fraction of outdoor ozone is lost when it is transported indoors, but the lost ozone has generated oxidized products, and typically the net concentration of these indoor oxidation products is larger than that of indoor ozone itself. Following transport indoors, a fraction of nitrogen dioxide disproportionates on indoor surfaces to nitric acid (HNO3) and nitrous acid (HONO); the latter then partitions between surfaces and the air.
Exposure assessments improve as accounting for the chemicals constituting the exposure improves. The more complete the exposure assessments, the more likely associations between exposures and adverse health effects will be uncovered. In examining associations between the chemical constituents of PM and adverse health effects, we should pay full attention not only to the chemical composition of outdoor PM, but also to the chemical composition of indoor PM that originates outdoors. The latter often contain SVOCs with large indoor concentrations (e.g., plasticizers, flame retardants, and pesticides). If we want to understand associations between ozone and morbidity/mortality, we should consider not only outdoor ozone, but also co-occurring indoor ozone and products generated by ozone-initiated indoor chemistry. If we want to understand associations between nitrogen dioxide and morbidity/mortality, we should consider not only outdoor nitrogen dioxide, but also co-occurring indoor nitrogen dioxide and nitrogen dioxide derived indoor HONO. A more complete understanding of human exposure to criteria pollutants can be achieved by paying full attention to the chemical transformations that occur when these pollutants are transported indoors.
Networking Poster Session
May 25, 2021
The networking poster session will take place in Gather.Town. The meeting link and password will be emailed it to you. If you have not received one and would like to join, email marina.vance@colorado.edu.
Posters have been grouped into 6 themes within indoor chemistry. Each poster has been assigned a letter (A,B,C,D) and a unique number (1-28). The numbers represent the location of each poster and the letters determine when presenters will be available by their posters for presentation (times in MT):
11:20-11:35: Group A (also marked by a purple lamp)
11:35-11:50: Group B (also marked by a friendly monstera plant)
11:50-12:05: Group C (also marked by a water cooler)
12:05-12:20: Group D (also marked by a beautiful statue)
12:20-1:00: Networking time!
*Students are encouraged to stand by their posters for longer than this minimum assigned time, but please be present for at least this time block.
Theme 1: Field campaigns in indoor chemistry
A-1: Determining Airflows and VOC Source Strengths for an Occupied School
Stinson, Brett (1); Laguerre, Aurélie (2); Gall, Elliott (3)
(1) Portland State University, (2) Portland State University, (3) Portland State University
Volatile organic compounds (VOCs) can impact human health, engage in chemistry indoors, and degrade air quality. In a near-roadway school, we determined airflows and quantified source strengths for VOCs over one week in May 2019. We developed an approach to estimate occupant density, outdoor air ventilation rates, and supply air flow rates through the school by analyzing the decay, steady-state, and accumulation periods of CO2 measured in return air. Calculated per-person emission rates for VOCs that are associated with human activity or metabolism, e.g., monoterpenes and isoprene, were consistent with estimates in the literature and indicate humans and their activities are an important indoor source of reactive VOCs. Source strengths for BTEX compounds, which are typically associated with traffic-related air pollution (TRAP), revealed that the majority of their presence was due to supply air, which was expected considering the elevated levels of outdoor TRAP constituents in the near-roadway building. This study provides new data concerning VOC source strengths of indoor and outdoor origin to a building, which can enable the modeling of air pollution exposures in schools.
B-2 Measurements of hydroxyl radical concentrations during cooking events: Evidence of an unmeasured indoor radical source
Reidy, Emily (1); Bottorff, Brandon (1); Rosales, Colleen (1); Stevens, Philip (1); HOMEChem Science Team
(1) Indiana University Bloomington
The hydroxyl radical (OH) is the dominant oxidant in the outdoor environment, controlling the lifetimes of volatile organic compounds (VOCs) and contributing to the growth of secondary organic aerosols (SOA). Despite its importance outdoors, there have been relatively few measurements of OH radical concentrations in indoor environments. During the House Observations of Microbial and Environmental Chemistry (HOMEChem) campaign, we observed elevated concentrations of OH during cooking events, particularly during the preparation of a traditional Thanksgiving dinner, which required the use of the gas range almost continually for six hours. The measured OH concentrations (2-6E6 molecules/cm3) could not be reproduced by a chemical model based on the Regional Atmospheric Chemistry Mechanism. However, interferences associated with the measurements of nitrogen dioxide (NO2) and ozone suggest that a photolytic VOC similar to pyruvic acid was emitted during use of the gas stove. Adding a surrogate VOC into the model that photolyzes to produce a peroxy radical (RO2) results in better agreement between the model and the OH measurements.
C-3 The Indoor PFAS Assessment Campaign: Study Design and Preliminary Results
Clara M. A. Eichler (1), Naomi Y. Chang (1), Daniel E. Amparo (1), Jason D. Surratt (1), Glenn C. Morrison (1), and Barbara J. Turpin (1)
(1) University of North Carolina at Chapel Hill
Per- and polyfluoroalkyl substances (PFAS) are chemicals used in a variety of consumer products and some are associated with adverse health effects. However, few indoor PFAS data exist. Here, a field campaign is presented that aims at measuring a broad range of PFAS in single-family homes. Samples of indoor air, airborne particles, settled dust, clothing, tap water, heating and air conditioning (HAC) condensate, and surface films will be collected in 10 homes over the course of 6-9 months. Temperature, relative humidity, and HAC operation will be monitored. Samples will be analyzed for individual PFAS, total organic fluorine, organic and elemental carbon, total water-soluble organic carbon, and major ions that regulate water uptake and pH. Particle mass and CO2 concentrations will also be measured. The results from the analyses in combination with qualitative data from home surveys and activity checklists will be used to characterize each home with respect to its PFAS chemistry and to assess factors that may influence PFAS fate and transport. This small study will improve our understanding of PFAS partitioning among indoor compartments and the role of thermodynamic parameters.
D-4 Indoor Chemistry of Cooking and Cleaning Emissions
Mehra, Archit (1); O’Leary, Catherine (2); Harding-Smith, Ellen (2); Shaw, Marvin (2); Thompson, Matthew (2); Jones, Harriet (1); Dillon, Terry (2); Jones, Benjamin (3); Davies, Helen (2); Carslaw, Nicola (2); Phillips, Gavin (1)
(1) University of Chester, UK (2) University of York, UK (3) University of Nottingham, UK
“Indoor air quality (IAQ) in our homes is influenced by emissions from cooking and cleaning activities. Cooking generates high concentrations of particulate matter (PM) while cleaning products represent a large source of volatile organic compounds (VOC). Emission rates of these species vary widely, dependent on the types of cleaning products used, cooking methods and food types.
Alongside primary emissions, secondary pollutants formed through chemical reactions indoors can have damaging effects on human health. It is thus important to understand the sources and reactions of pollutants in typical domestic settings. In the UK, focus on energy efficiency has made homes more airtight, and thus a large proportion of housing stock has low ventilation rates, giving emissions plenty of time to undergo chemistry indoors.
We present preliminary findings from a study of emissions and processing of VOC and aerosols from cooking and cleaning carried out in the University of Chester’s DOMESTIC facility. These experiments contribute to the EPSRC funded IMPacts of Cooking and Cleaning on indoor Air quality: towards healthy BuiLdings for the futurE project.”
Theme 2: Indoor aerosols
A-5 The Viscosity of Organic Films from Cooking Aerosol
Kiland, Kristian (1); Li, Ying (2); Marroquin, Kevin (1); Xu, Shaun (1); Shiraiwa, Manabu (2); O’Brien, Rachel (3); Bertram, Allan (1)
(1) The University of British Columbia, (2) University of California, Irvine, (3) William & Mary
Organic aerosols generated from cooking processes are abundant in indoor environments. The viscosity of cooking organic aerosols (COA) has consequences for their role in indoor air chemistry and air quality. The viscosity of COA film samples from the HOMEChem field study was measured. The samples had different viscosities based on their collection method. Collection was done by either (1) extraction with acetonitrile or (2) physically scraping with a razor blade. For the acetonitrile extract, the viscosity was measured with the poke-flow technique. The viscosity of the acetonitrile extracts was shown to be semi-solid or liquid-like (viscosity less than 10^4 Pa s), which was much lower than predicted by a molecular-weight based viscosity model. By including unsaturation in the model, the predictions agree with the measurements. Compared to the acetonitrile extract, the scraped sample appeared to be more solid-like. A novel softening technique was developed to measure the scraped sample viscosity.
B-6 Kinetic multi-layer modelling of the effect of self-assembly on the reactivity of a cooking emission proxy
Milsom, Adam (1); Squires, Adam (2); Pfrang, Christian (1,3)
(1) University of Birmingham, School of Geography Earth and Environmental Sciences, Birmingham, UK (2) University of Bath, Department of Chemistry, Bath, UK (3) University of Reading, Department of Meteorology, Reading, UK
The phase state of organic aerosols and films can affect the reactive lifetime of molecules within them. Here we apply a kinetic multi-layer model to ozonolysis experiments carried out in capillary tubes coated with a viscous self-assembled oleic acid-based proxy for cooking emissions. We found that self-assembled phase formation, measured by X-ray scattering, increased the reactive half-life of the coated film. Lifetimes ranged from hours to days. Moreover, the formation of a surface region of higher order oxidation products contributes to the reduced diffusivity of ozone through the film. These findings demonstrate the potential impact of fatty acid self-assembly on the atmospheric lifetime of cooking emissions.
C-7 Indoor black carbon and brown carbon concentrations from cooking and outdoor penetration
Sankhyan, Sumit (1); Patel, Sameer (1); DeCarlo, Peter (2); Farmer, Delphine (3); Goldstein, Allen (4); Katz, Erin (2); Nazaroff, William (4); Novoselac, Atila (5); Tian, Yilin (4); Vance, Marina (1)
(1) University of Colorado Boulder, (2) Drexel University, (3) Colorado State University, (4) University of California at Berkeley, (5) University of Texas at Austin
Particle emissions from cooking are a major contributor to household indoor air pollution. An important constituent of these emissions is light-absorbing carbon, including black carbon (BC) and brown carbon (BrC). During the month-long HOMEChem experiment, cooking was the major source of BC and BrC indoors, leading to concentrations that were ~2-10 times higher than in periods of no activity in the test house. The median indoor-to-outdoor ratios of BC and BrC during the periods of no activity inside the test house were 0.6 and 0.7, respectively. The investigation of AAE values for different experimental days showed an increase with the intensity of cooking activities due to the dominance of BrC particles in cooking emissions. The indoor BC exposure assessment performed in this study for a kitchen microenvironment showed that cooking emissions are one of the main sources of indoor BC exposure and, in case of our experimental setup, cooking 3-4 meals a day doubled the BC exposure for an occupant residing in the kitchen area compared with exposure during background conditions.
Theme 3: Indoor gas-phase constituents
A-8 Indoor sunlight during bleach mopping induces radical chemistry and changes in indoor air quality
Rosales, Colleen Marciel F. (1); Reidy, Emily K. (2); Bottorff, Brandon P. (2); Kumar, Vinay (1); Stevens, Philip (1, 2); Boor, Brandon (3, 4); Jiang, Jinglin (3, 4); Lahib, Ahmad (1, 5); Dusanter, Sebastien (5); Tomas, Alexandre (5); HOMEChem Science Team
(1) O’Neill School of Public and Environmental Affairs, Indiana University; (2) Department of Chemistry, Indiana University; (3) Lyles School of Civil Engineering, Purdue University; (4) Ray W. Herrick Laboratories, Center for High Performance Buildings, Purdue University; (5) IMT Lille Douai, Institute Mines-Telecom, Univ. Lille, Center for Energy and Environment
During the current pandemic, cleaning and disinfection are inevitable. A commonly used product for disinfection is bleach, in which the active ingredient is hypochlorous acid, HOCl (or its conjugate base, OCl-). Bleach is used due to its efficacy in eliminating viruses, but little has been done to evaluate its chemical toxicity and potential to form oxidants (e.g., radicals and secondary chemical species), some of which may present discomfort or harm to humans. In this study, we looked at mopping experiments done in two indoor environments and measured concentrations of precursors, radical intermediates, and oxidation products. In both experiments, indoor sunlight through windows was enough to initiate the breakdown of gaseous HOCl and Cl2, which produced OH and Cl, which in turn oxidized volatile organic compounds (VOCs) indoors. Furthermore, we shed light on the dominant chlorine-initiated mechanisms involved in the breakdown of propane, a VOC most commonly associated indoors with gas stoves. With these observations, we recommend changes in behavior such as careful choice of cleaning products, increased room ventilation, and scheduled cleaning during specific times of the day.
B-9 INCHEM-Py: An open source indoor air chemistry model
Shaw, David (1); Carslaw, Nicola (1).
(1) Department of Environment and Geography, University of York, United Kingdom
The new INdoor CHEMical model (INCHEM-Py) is a refactor and development of the internationally recognised INdoor Detailed Chemical Model (INDCM). It is written in Python and has been made available as open-source software to increase access and allow for collaborative development.
INCHEM-Py resolves the complex air chemistry of indoor environments through time with the incorporation of an explicit chemical mechanism that considers the step-by-step degradation of around 150 common volatile organic compounds. The model also considers indoor photolysis (combination of attenuated outdoor plus artificial lighting), exchange with outdoor air, and emissions from/deposition to surfaces. The chemical detail allows the user to understand key reaction pathways and identify the species that accumulate to high concentrations for a range of conditions that are commonly encountered indoors. All species can be traced through the model and output alongside key time dependent parameters.
The presented poster includes a description of INCHEM-Py from the setting of initial parameters and variables, the formation of the system of ordinary differential equations and their solution.
C-10 How does the outdoor environment affect indoor air chemistry? Bridging the gap using modelling studies
Carter, Toby (1); Carslaw, Nicola (1)
(1) University of York
The impact of air pollution has been a prominent issue over the last few decades. Despite the world becoming increasingly aware of the numerous health effects associated with air pollution, policies to remediate against its consequences are often absent. However, indoor air quality has become an increasing area of concern, given that in developed countries, humans spend 90% of their lives indoors. Outdoor air pollution can have a significant impact on indoor air quality, particularly for buildings close to a busy road, an airport, or industrial sites. Pollutants which originate from outdoor environments can infiltrate the home and thus react with those emitted indoors, from cooking and cleaning, forming a myriad of potentially harmful compounds. There is presently a knowledge gap in our understanding of how these compounds form and what chemical processes are involved. The INCHEM-Py model is designed to provide insight behind the chemical processes and transformations that occur in an indoor environment. This model utilises a detailed mechanism for the breakdown of common VOCs indoors and also includes terms for deposition, emissions, photolysis, and exchange of air with outdoors.
D-11 VOC emissions from quaternary ammonium disinfectant agents
Jahn, Leif (1); Bhattacharyya, Nirvan (1); Blomdahl, Daniel (1); Tang, Mengjia (1); Abue, Pearl (1); Novoselac, Atila (1); Hildebrandt Ruiz, Lea (1); Misztal, Pawel (1)
(1) University of Texas at Austin
Quaternary ammonium-based disinfectant products (quats) have seen significantly increased usage in recent years as components in commercial cleaning and disinfection products. Quats are generally expected to be more inert and potentially less harmful than traditional disinfectants. To study the potential for VOC emissions during quat usage, a Vocus PTR-ToF-MS was used to analyze VOC emissions during headspace and environmental chamber measurements of a solution prepared from pure benzalkonium chloride (BAC). A number of VOCs are detected and likely originate, in part, from BAC synthesis. These include compounds that are likely solvents (benzene and ethanol), synthesis byproducts (benzaldehyde), and residual synthetic reagents (chloropropene and benzal chloride). Some of these molecules are also detected in commercial products, though complex product formulations may also contain such molecules for other reasons. Headspace measurements of a novel quat-silane commercial product were also performed. Overall, these results show that quat-based cleaning agents can emit VOCs during usage and highlight the potential significance of the synthetic process in affecting the emitted VOCs.
Theme 4: Indoor human exposure
B-12 Surface Residuals of Quaternary Ammonium Compounds can be Detected Hours after Disinfectant Application
Barber, Olivia Williams (1); Hartmann, Erica M. (1)
(1) Northwestern University
Disinfection is used throughout healthcare facilities to reduce pathogen loads on surfaces and the risk of healthcare-acquired infections (HAIs). Some disinfectant actives, such as hydrogen peroxide and sodium hypochlorite, break down into non-biocidal compounds within a few minutes of being used to disinfect surfaces. Other active, such as quaternaries and quat-siloxane polymers are retentive on surfaces and can retain some biostatic/biocidal properties. Over time in the absence of reapplication, remaining actives will fall to subinhibitory concentrations, which can allow bacteria to interact with the compounds and develop resistance. The evolution of antibiotic resistance in response to quats on hospital surfaces has not been demonstrated, but several studies indicate that this phenomenon is possible. To investigate whether residual disinfectant actives could be detected at subinhibitory concentrations after application, we examined changes in active residual concentrations of a quaternary ammonium disinfectant over time.
A-13 Implementation and Evaluation of 100 Clean Cookstoves In Nuevo Amanecer, Nicaragua
Ghezzi, Zachary (1); Jain, Manav (1); Aurelio, Caroline (1); Sanchez, Camila (1); Gonzalez, David (1)
(1) Georgia Institute of Technology
In Nuevo Amanecer, a rural community located near Matagalpa, Nicaragua, citizens primarily utilize an open three-stone fire for cooking. These stoves can expose operators to high levels of CO and PM2.5, which have been correlated to respiratory and cardiovascular health issues. Engineers Without Borders (EWB) at Georgia Tech worked to address this problem by installing 100 clean cook stoves in the area through collaboration with Rayo de Sol, a local NGO, as well as Proleña, a Nicaragua-based stove manufacturer. These clean stoves work to ventilate the harmful gases and particulates in order to improve health in the homes. Although the Georgia Tech EWB Project was unable to travel last summer, Nicaragua-based EWB field engineers performed air quality tests on a sample of stoves in order to ensure stove efficacy. Through testing, it was determined that there were significant decreases in CO and PM2.5 levels in the clean cookstoves relative to the open fires. The EWB team currently continues to monitor the quality and satisfaction of the stoves through testing and community surveys in preparation for closing out in the next year.
B-14 Textile Washing Conveys SVOCs from Indoors to Outdoors: Application and Evaluation of a Residential Multimedia Model
Kvasnicka, Jacob (1); Cohen Hubal, Elaine (2); Rodgers, Timothy F. M. (1); Diamond, Miriam L. (1)
University of Toronto (1), U.S. Environmental Protection Agency (2)
Textiles provide a large surface area for accumulating SVOCs from indoor air, which can be transported to outdoors through washing. A multimedia model was developed to estimate advective transport rates (fluxes) of 14 SVOCs from indoors to outdoors at steady state for textile washing, ventilation, and dust removal/disposal. Median calibrated aggregate emission rates to indoor air ranged from 1.7 to 18,300 [ng·(h·home)-1] for BDE-28 and DEP, respectively. Differences in emission rates, rather than physical-chemical properties, drove the variability in losses to outdoors. Median fluxes [µg·(year·home)-1] ranged from 2 (BDE-28) to 30,200 (DEP) for textile washing, 12 (BDE-28) to 123,200 (DEP) for ventilation, and 0.1 (BDE-28) to 4,200 (DEHP) for dust removal. On average, textile washing contributed 20% (TCPP) to 62% (TBOEP) of the total flux to outdoors. These results suggest that residential textile washing can be an important transport pathway for SVOCs emitted to indoor air, with implications for human and ecological exposure. Interventions should try to balance the complex tradeoff of textile washing to minimize exposures for both human occupants and aquatic ecosystems.
C-15 Per- and Polyfluoroalkyl Substances (PFAS) in Airborne Particulate Matter (PM2.0) Emitted During Floor Waxing
Zhou, Jiaqi (1); Baumann, Karsten (1); Chang, Naomi (1); Morrison, Glenn (1); Bodnar, Wanda (1); Zhang, Zhenfa (1); Atkin, Joanna (2); Surratt, Jason (1), (2); Turpin, Barbara (1).
(1) Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. (2) Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Per- and polyfluoroalkyl substances (PFAS) have been widely used in industrial and consumer products, including floor waxes. Therefore, floor waxing workers, who have close contact with floor waxes, might be exposed to PFAS. Studies have shown that adverse health effects are associated with PFAS exposures (e.g., increased risk of cancer); however, exposures resulting from the use of floor waxes are poorly understood. This study measured PFAS in dust and airborne particulate matter (PM2.0) before, during, and after floor stripping/waxing activities in two university laboratories and a hallway and estimated occupational exposures. Samples were analyzed for 34 targeted PFAS by UHPLC/ESI-MS/MS. Ten PFAS were detected in PM2.0 at concentrations of <0.11-33.8 pg m-3. Five were consistently higher during floor stripping/waxing compared to before, with estimated emission rates of 1.5-9.6 ng h-1m-2. Six PFAS were detected in floor dust samples with concentrations of <0.01-17.6 ng m-2. Further, we estimated PFAS inhalation occupational exposures in the range of 9.42-23.2 pg kg-1 h-1, which are higher than average residential indoor and ambient outdoor inhalation exposures.
D-16 Characterizing partitioning behavior of VOCs to cotton fabric
Yu, Jie(1); Abbatt, Jonathan P. D. (1)
(1) University of Toronto
Chemical accumulation from the environment to indoor surfaces and clothing can influence human exposure & raise health concerns. Clothing can be a barrier or a reservoir for newly absorbed chemicals depending on clothing history. Limited clothing-mediated exposure studies have characterized some SVOCs accumulations, but systematic VOC & SVOC partitioning studies are lacking. Here, the cotton-air equilibrium partition coefficient (Kca) for carbonyls, carboxylic acids & aromatics are measured by thermally desorbing soiled fabrics, analyzed with PTR-ToF-MS. Rapid 1-3 days equilibration time was shown. Kca’s are similar for larger carbonyls & carboxylic acids with same carbon numbers, but are smaller for corresponding aromatics, probably due to lower polarity. Linear Kca vs Koctanol-air trends were seen for carbonyl & aromatic homologous series. Although a combination of chemical interactions were expected for smaller carboxylic acids due to the presence of water in cotton fabric, Kca for larger acids scale upward with Koa. Full equilibration of fabric surface & bulk with ambient air have been reached, supported by no change in uptake weeks after initial exposure in early measurements.
A-17 Exposures, Source Apportionment, and Intake Fractions of Volatile Organic Compounds (VOCs) at Two California Residences
Lunderberg, David M. (1); Liu, Yingjun (1); Misztal, Pawel K. (1); Tian, Yilin (1); Arata, Caleb (1); Weber, Robert J. (1); Kristensen, Kasper (1); Nazaroff, William W (1); Goldstein, Allen H. (1)
(1) University of California, Berkeley
More than 200 volatile organic compounds (VOCs) were observed in two California residences over three intensive monitoring campaigns. We quantified occupant exposures to these VOCs using (a) time-resolved concentration data acquired via proton transfer reaction time-of-flight mass spectrometry and (b) activity patterns acquired via occupant logs. Source apportionment analysis assigned exposures to four source categories: continuous indoor sources, outdoor-to-indoor transport, cooking, and other. For most VOCs, exposures were primarily attributed to continuous indoor sources. Chronic advisory health guidelines were available for a subset of observed VOCs. Concentrations of acrolein, acetaldehyde, and acrylic acid exceeded health guidelines, whereas concentrations of other assessable VOCs were well below guideline levels. We also estimated individual intake fractions (iFi, mass inhaled by an individual per unit mass emitted) for observed VOCs and for inert tracer gases released in the crawlspace, living space, and attic. Although temporal behavior and physical properties varied among observed VOCs, their iFi values were clustered near the iFi values of the living space tracer gases.
Theme 5: Indoor surfaces
B-18 Assessing Behavior of Thirdhand Smoke Indoors: Observing Multiphase Ozonolysis of Tetrahydrocannabinol in Cannabis Smoke
Yeh, Kristen (1); Abbatt, Jon (1); Wania, Frank (1); Li, Li (2)
(1) University of Toronto; (2) University of Nevada, Reno
A source of chemical exposure to humans, thirdhand smoke (THS) refers to the contamination that persists indoors following the cessation of smoking. The composition of THS depends on the substance from which it originated. Although past studies have investigated the effects of thirdhand tobacco smoke on indoor air quality and human health, few have focused on other kinds of THS. Cannabis smoke is becoming increasingly prevalent in many countries due to decriminalization. As such, understanding the chemical composition and reactive fate of indoor thirdhand cannabis smoke (TCS) is necessary to mitigate exposure to potentially harmful products. The heterogenous reaction of surface-deposited delta-9-tetrahydrocannabinol (THC), a major component of cannabis smoke, with ozone was examined inside of an environmental chamber. Oxidative decay was monitored by liquid chromatography-mass spectrometry. Additionally, 2D phase partitioning plots were used to assess the partitioning behavior of THS components from tobacco smoke, e-cigarette vapor, cannabis, methamphetamine, and cocaine smoke. This information improves our knowledge of THS behavior and can better inform indoor exposure models.
C-19 Endogenous Reactivity in Deposited Cigarette Smoke and Implications for Third-Hand Smoke
Hurlock, April M. (1); Collins, Douglas B. (1).
(1) Bucknell University
Little is known about the effects of so-called ‘third-hand smoke’ (THS) on the environment and human health. THS is a collection of chemicals from cigarette smoke that adhere to indoor surfaces and extend the exposure risks for bystanders. Due to the long lifetime of THS films, we hypothesize that reactions occur between chemicals within the deposited film or with the surface itself. Cigarette smoke was collected on horizontal glass substrates and incubated for up to one week. Targeted analysis of aqueous extracts of the glass were performed using LC-Orbitrap MS. The amount of nicotine decreased and nicotine 1’-N-oxide increased over time, signifying that nicotine was removed by oxidation reactions occurring within THS films. The influence of pre-deposited organic films on THS composition were investigated. Early results suggest that organic films may affect the partitioning behavior of nicotine-related compounds. Future studies will look to include a wider variety of pre-deposited films, different substrate materials, and changes to environmental factors in order to obtain a better understanding about what goes on after the cigarette goes out.
D-20 Determining and Modeling the Behavior of VOCs on Indoor Wood Surfaces
Ziola, Anna (1,2); Ziemann, Paul (1,2)
(1) University of Colorado Boulder, (2) Cooperative Institute for Research in Environmental Sciences
Without knowing how VOCs interact with specific surfaces, it is difficult to predict the fate of molecules in a room with many. By isolating the behavior of VOCs with individual surfaces, indoor models can be improved and give better insight into where VOCs are coming and going. To study VOC interactions with wood surfaces, VOC-filled air is flown through a wood tube, creating a chromatography-like experiment where VOCs interact with and equilibrate with the tube surface as they pass through and into an iodide CIMS. Then, absorptive capacity values and diffusion coefficients are calculated using an experimental model and an ATR-FTIR with thin varnish films. These experiments have shown that the behavior of VOCs indoors relies less on the identity of the wood and more on the identity of the varnish. Shellac, one of the varnishes studied, has little interaction with carboxylic acids, but lacquer, a widely used varnish, has a much higher absorptive capacity and absorbs a relatively large amount of the VOCs that contact the surface. These absorptive capacity and diffusion coefficient values obtained can then be incorporated into larger indoor atmospheric models.
A-21 Multiphase Mechanism and Quantitative Product Analyses in Ozonolysis of Unsaturated Lipids
Zhou, Zilin (1); Lakey, Pascale S. J. (2); Shiraiwa, Manabu (2); Abbatt, Jonathan P. D. (1)
(1) University of Toronto, (2) University of California, Irvine
Unsaturated lipids, particularly oleic acid and their derivatives, are commonly found on indoor surfaces and human skin. It is well known that theses lipids decay rapidly under ozone, following the Criegee mechanism. Here, we studied the surface ozonolysis reactions of multiple lipids. The quantitative analyses suggest that, under dry conditions, up to 80% of the products in the condensed phase are secondary ozonides, whose formation is significantly suppressed by elevated relative humidity (RH). This is due to the reaction between Criegee intermediates (CI) and water, forming gas-phase hydrogen peroxide and aldehydes. Such behavior in product composition is used to constrain a multiphase kinetics model of triolein (a triglyceride derived form oleic acid) ozonolysis. Modelled results show that the lipid decay is driven by the reaction near the surface, while the rate occurring in the bulk is significant reduced. Although the reduction in secondary ozonide yields under high RH is well predicted, the model overestimates the production of H2O2 and aldehydes, perhaps because a mass transfer constraint plays a more important role in secondary product formation or missing chemistry.
B-22 Humidity and Uptake of a Model Organic Peroxide on Naturally Soiled Indoor Window Surfaces
Marc Webb (1), Liyong Cui (1), Karsten Baumann (1), Jason Surratt (1), Glenn Morrison (1), Joanna Atkins (1), Barbara Turpin (1)
(1) University of North Carolina at Chapel Hill
Adsorbed water on abundant surfaces may influence the fate of indoor water-soluble organic gases through aqueous-mediated surface uptake. Here, the effect of relative humidity (RH) on the deposition velocity (vd) and reaction probability (γ) of a model organic peroxide to naturally soiled indoor window surfaces was investigated, using isoprene hydroxy hydroperoxide (ISOPOOH) as the model compound. Glass was soiled in 3 local homes for 1+ years and composition measured. The uptake of ISOPOOH by clean and soiled glass was measured under 5%, 55%, and 85% RH conditions using a novel indoor surface flow reactor coupled to a chemical ionization mass spectrometer (CIMS). Under humid conditions, initial peroxide uptake resulted in 78% removal to soiled glass and only 24% removal to clean glass. Under dry conditions, there was no significant enhancement of peroxide uptake to soiled glass compared to clean glass. Steady-state vd and γ to soiled glass at 55% RH was 0.003-0.001 cm/sec and 3.3E-7-6.0E-8, respectively. Reversibility and implications of uptake will be discussed. This work contributes parameters for predictive modeling.
C-23 Painted surfaces, NOx and indoor lighting: comparing photocatalytic paint and non-photocatalytic paint
Jones, Stephanie (1); Vallieres, Morgan (1); Schwartz-Narbonne, Heather (1); Hosse, Florian (2); Yang, Xiaoying (1); Donaldson, D. James (1)
(1) University of Toronto, Canada (2) Université d’Orléans, France
Surface chemistry is believed to play a key role in the indoor environment owing to the large surface to volume ratio. Painted surfaces are ubiquitous indoors and the presence of photocatalytic material in paint may allow heterogeneous photochemistry to occur under indoor lighting (> 320 nm). Potential heterogeneous reactions could occur with gaseous species such as NOx, arising from combustion sources and infiltration from outdoors. Here we present new results on the interaction of NOx with photocatalytic paint in the presence of indoor lighting and compare it with previous results for paint not marketed as photocatalytic. We consider nitrate (NO3-) deposited on to the painted surface and the addition of nitric oxide (NO) in the gaseous phase to the painted surface. Different NOx product distributions are observed between the two paints for different light sources and humidity conditions. We conclude that individual paint formulations dictate product distribution and the chemistry cannot be generalised for all types of paint.
D-24 Withdrawn
A-25 Reactions of indoor relevant surfaces with bleach cleaning products
Deeleepojananan, Cholaphan (1); Alves, Michael (1); Grassian, Vicki
(1) Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
The use of household bleach cleaning products results in emissions of highly oxidative gaseous species, such as hypochlorous acid (HOCl) and chlorine (Cl2), that have the potential to participate in heterogeneous reactions with indoor relevant surfaces. Using attenuated Fourier-transform infrared (ATR-FTIR) spectroscopy, we show that silica (SiO2), a proxy for window glass, and titanium dioxide (TiO2), a component of paint and self-cleaning surfaces, act as a reservoir for (HOCl) through heterogeneous reactions by forming mostly irreversible adsorbed chlorine-containing surface products. We have determined that the surface chemistry differs between these two surfaces with Si-O-Si and Ti-OH groups, reacting respectively with HOCl. In addition, preliminary data from exposure of these surfaces with HOCl as well as limonene, a common indoor volatile organic compound, in an environmental Teflon chamber along with identification of extracted surface products by mass spectrometry suggests that surface-catalyzed reactions occurred on the chlorinated TiO2 surface, in particular, leads to the formation of new chlorine and oxygen-containing products.
Theme 6: Surface-gas-aerosol interactions
B-26 Carpet sorption of volatile organic compounds
Morris, Melissa A. (1); Pagonis, Demetrios (1); de Gouw, Joost A. (1); Ziemann, Paul J. (1); Jimenez, Jose L. (1)
(1) University of Colorado
Carpet has been shown to act as a large indoor reservoir of VOCs, taking up VOCs when concentrations are high and emitting VOCs when concentrations are low. The ubiquitous nature of carpet as a flooring material makes it important for indoor air modeling. We aim to better understand the sorption mechanism of carpet, as carpet has been described in the literature as adsorptive (with molecules binding to the surface), but carpet materials (synthetic polymers) have been shown to absorb VOCs (with molecules being dissolved in the bulk material). If carpet absorbs VOCs, it will be able to hold orders of magnitude more VOCs than previously reported, and emit VOCs for longer. We also aim to quantify the sorptive capacity of carpet. Initial experiments flowed VOCs through tubing made of polymers relevant to carpet, measured the delays caused by tubing-VOC interactions, and fit the delays using a 1-D mass flow box model to quantify the sorptive capacity. Ongoing work involves rolling carpet itself into a tube shape for sorption testing, and updating the model to include diffusion into layers deeper in the material, to better model the partitioning dynamics of complex materials like carpet.
C-27 Henry’s law constants and indoor partitioning of microbial volatile organic compounds
Wu, Shuang (1); Hayati, Siti (2); Zhao, Ran (3).
(1) University of Alberta, (2) University of Alberta, (3) University of Alberta.
Indoor microbial activities can generate air pollutants referred to microbial volatile organic compounds (MVOCs). MVOCs can be odorous and cause adverse health effects to the occupants. Recent studies have discovered an unexpectedly large volume of polar and weakly polar reservoirs of organic compounds. Henry’s law constant (H) and the octanol-air partitioning coefficient (Kao) are the key parameters to describe the partitioning behaviors of indoor pollutants. However, literature H values of MVOCs are sparse and inconsistent. The focus of this research is to experimentally determine H of MVOCs. Inert gas-stripping (IGS) and headspace ratio techniques were combined with gas chromatography-flame ionization detection (GC-FID) to determine the H values. Using test compounds, we achieved an excellent agreement between the two methods and the literature. The H values of four typical indoor MVOCs at 15, 25, 35 and 50°C were obtained. The two-dimensional chemical partitioning space plots were applied to display the indoor phase distribution of target chemicals.
D-28 “Chemistry in the Art Gallery”: Using Indoor Environments as a Framework for Teaching Atmospheric Chemistry
Sharma, Mya* (1); McCallum, Kay* (1); Styler, Sarah A. (1).
(1) McMaster University
Atmospheric chemistry is often taught using outdoor systems; although this provides a relevant learning framework for students, it neglects indoor environments. To create a similar reference point for indoor chemistry education, we created the module “Chemistry in the Art Gallery” at McMaster University, which introduces indoor air chemistry concepts to students of diverse backgrounds through the context of spaces housing cultural heritage, such as museums and art storage enclosures. This module covers the damaging effects of pollutants on art and the chemical reactions by which these effects occur, the pollutant monitoring and mitigation techniques used by art conservators, and the equity considerations associated with indoor air quality research in museums. We developed complementary, accessible, and remote in-class activities for students to examine the accumulation of particulate matter on art surfaces, the effects of anoxic environments and light exposure on pigments, and the relationship between levels of pollutant exposure and damage. This module provided students a better understanding of the indoor environments they experience and the chemistry in the world around them.
Meeting program: www.indoorchem.org/indoorchem2021