7 research outputs found
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Indoor Black and Brown Carbon from Cooking Activities and Outdoor Penetration: Insights from the HOMEChem Study
Particulate matter emissions from cooking activities are a major contributor to indoor air pollution in households. A major part of these emissions consists of light absorbing aerosols known as black carbon (BC) and brown carbon (BrC). The goal of this work was to characterize the contributions of indoor and outdoor sources of BC and BrC to the indoor environment by measuring real-time concentrations of these components indoors and outdoors concurrently during the month-long HOMEChem field study in June 2018. We quantified the penetration of BC and BrC into the house from outdoor sources and characterized the impacts of cooking activities on indoor air quality in terms of BC and BrC concentrations, including exposure and dose calculations. The BC exposure was at least 4 times higher during the preparation of any cooked meal than during a comparable period of no activity. The exposure and dose during a simulated Thanksgiving Day were highest with BrC concentrations peaking at 6390 ng m-3. The Power law fitting approach was used to calculate angstrom exponent (α) for characterizing aerosol emissions during different activities. The value of α ranged from 1.1 to 3.67 during the entire campaign, with the lowest value (indicative of BC-dominated aerosols) observed in periods of no activity and the highest value (indicative of BrC-dominated aerosols) observed during the Thanksgiving Day experiments. Real-time data collected in this study improves our understanding of the generation of BC and BrC indoors and the effects of outdoor air pollution on indoor air quality
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Aerosol Science and Engineering Research for Mitigating Human Exposure and Improving Indoor Air Quality
Aerosol science and engineering research can serve important roles in studying and improving Indoor Air Quality (IAQ) in residential settings and in assessing mitigation strategies related to the associated particulate matter (PM) exposure. In this dissertation, I present the results from four studies related to these timely topics. The first study focused on the assessment of PM2.5 concentrations and transport in indoor residential environments using commercially available air quality monitors (AQM). Consumer-grade, low-cost PM sensors are gaining popularity as a convenient tool for consumers to monitor indoor air quality in their homes, so we investigated five commercially available AQMs (IQAir AirVisual Pro, Foobot Home, PurpleAir PA-II-SD, and PA-I-Indoor) and compared their response to a research-grade optical particle counter (OPS 3330, TSI Inc.) by deploying them in four different houses over a period of 9-12 weeks each. Additional objectives of this study also included studying indoor PM transport between the kitchen and bedroom areas due to cooking in different homes and evaluating the reduction of PM2.5 exposure in residential homes by using a portable air cleaner in kitchen and bedroom areas respectively. The second study investigated aerosol emissions, their volatility, and respiratory deposition characteristics associated with the use of different cooking oils at multiple cooking temperatures. Oils tested include canola, peanut, soybean, coconut, and lard. This study was aimed to bring indoor cooking measurements into perspective by isolating frying oil emissions from other ingredients and understanding the fate of these emissions in an indoor setting. The third study compared filtration efficiencies of different face covering options widely available in the market and investigated the potential for reusability of cotton cloth masks by repeated machine washing and drying. The results from this study will facilitate a better understanding of the relative protection of different masks against respiratory disease transmission in addition to reducing PM2.5 exposure during wildfire events. An extension of this study involved developing improved cloth filter materials using a coating of biodegradable cellulose nanofibril in order to promote sustainable face mask usage. Overall, these studies demonstrated the role experimental aerosol research can have in understanding and reducing different indoor sources of aerosols primarily due to cooking, thus leading to potential improvements to indoor air quality and, consequently, to human health.</p
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Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures.
It is important to improve our understanding of exposure to particulate matter (PM) in residences because of associated health risks. The HOMEChem campaign was conducted to investigate indoor chemistry in a manufactured test house during prescribed everyday activities, such as cooking, cleaning, and opening doors and windows. This paper focuses on measured size distributions of PM (0.001-20 μm), along with estimated exposures and respiratory-tract deposition. Number concentrations were highest for sub-10 nm particles during cooking using a propane-fueled stovetop. During some cooking activities, calculated PM2.5 mass concentrations (assuming a density of 1 g cm-3) exceeded 250 μg m-3, and exposure during the postcooking decay phase exceeded that of the cooking period itself. The modeled PM respiratory deposition for an adult residing in the test house kitchen for 12 h varied from 7 μg on a day with no indoor activities to 68 μg during a simulated day (including breakfast, lunch, and dinner preparation interspersed by cleaning activities) and rose to 149 μg during a simulated Thanksgiving day
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Indoor black carbon and brown carbon concentrations from cooking and outdoor penetration: Insights from the HOMEChem study
Particle emissions from cooking are a major contributor to residential indoor air pollution and could also contribute to ambient concentrations. An important constituent of these emissions is light-absorbing carbon, including black carbon (BC) and brown carbon (BrC). This work characterizes the contributions of indoor and outdoor sources of BC and BrC to the indoor environment by concurrently measuring real-time concentrations of these air pollutants indoors and outdoors during the month-long HOMEChem study. 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 absorption Ångström exponent was used to characterize light-absorbing particle emissions during different activities and ranged from 1.1 to 2.7 throughout the campaign, with the highest value (indicative of BrC-dominated emissions) observed during the preparation of a simulated Thanksgiving Day holiday style meal. An indoor BC exposure assessment shows that exposure for an occupant present in the kitchen area was ~4 times higher during Thanksgiving Day experiments (primarily due to candle burning) when compared to the background conditions.</p
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Optimization of a Do-It-Yourself Air Cleaner Design to Reduce Residential Air Pollution Exposure for a Community Experiencing Environmental Injustices
The large-scale deployment of Do-it-yourself (DIY) air cleaners, especially in communities that historically bear the brunt of air pollution exposure-related injustices, provides communities a cost-effective option to reduce personal indoor exposure to particulate matter. In this study, we developed nine air cleaner prototypes, altering filter depth and the number and type of filters, and compared their PM2.5 removal effectiveness and maintenance-related parameters prior to deployment in North Denver, Colorado homes. Prototypes containing multiple high efficiency particulate air filters with a minimum reporting value of 13 (MERV13) had higher clean air delivery rates (CADR, >300 m3 h−1) compared to prototypes using a single filter (100–200 m3 h−1), but single-filter designs had comparable values of CADR normalized by initial and annual operating costs. Based on performance, cost, build time, and feedback from the community regarding concerns related to volatile organic compound exposure, the selected prototype (P9) used a combination of an activated carbon filter and single MERV13 filter with a 10.16 cm (4-inch) depth. Following this assessment, 120 of the selected air cleaner prototypes were built and deployed in homes around the communities in North Denver for two separate cohorts; feedback regarding their usage over the course of the deployment showed that in addition to the increased noise levels perceived by the participants, factors such as cold air flow from the air cleaner impacting the thermal comfort and aesthetics of the design reduced their usage time in homes. Future designs of DIY air cleaners could incorporate this feedback to help design improved features such as quieter air cleaners and real-time pollutant monitoring feedback to prompt users to keep them operational at all times of the day.</div
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Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures.
It is important to improve our understanding of exposure to particulate matter (PM) in residences because of associated health risks. The HOMEChem campaign was conducted to investigate indoor chemistry in a manufactured test house during prescribed everyday activities, such as cooking, cleaning, and opening doors and windows. This paper focuses on measured size distributions of PM (0.001-20 μm), along with estimated exposures and respiratory-tract deposition. Number concentrations were highest for sub-10 nm particles during cooking using a propane-fueled stovetop. During some cooking activities, calculated PM2.5 mass concentrations (assuming a density of 1 g cm-3) exceeded 250 μg m-3, and exposure during the postcooking decay phase exceeded that of the cooking period itself. The modeled PM respiratory deposition for an adult residing in the test house kitchen for 12 h varied from 7 μg on a day with no indoor activities to 68 μg during a simulated day (including breakfast, lunch, and dinner preparation interspersed by cleaning activities) and rose to 149 μg during a simulated Thanksgiving day
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Indoor emissions of total and fluorescent supermicron particles during HOMEChem.
Inhalation of particulate matter is associated with adverse health outcomes. The fluorescent portion of supermicron particulate matter has been used as a proxy for bioaerosols. The sources and emission rates of fluorescent particles in residential environments are not well-understood. Using an ultraviolet aerodynamic particle sizer (UVAPS), emissions of total and fluorescent supermicron particles from common human activities were investigated during the HOMEChem campaign, a test-house investigation of the chemistry of indoor environments. Human occupancy and activities, including cooking and mopping, were found to be considerable sources of indoor supermicron fluorescent particles, which enhanced the indoor particle concentrations by two orders of magnitude above baseline levels. The estimated total (fluorescent) mass emission rates for the activities tested were in the range of 4-30 (1-11) mg per person meal for cooking and 0.1-4.9 (0.05-4.7) mg/h for occupancy and mopping. Model calculations indicate that, once released, the dominant fate of coarse particles (2.5-10 micrometer in diameter) was deposition onto indoor surfaces, allowing for the possibility of subsequent resuspension and consequent exposures over durations much longer than the ventilation time scale. Indoor coarse particle deposition would also contribute to soiling of indoor surfaces