1
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Souza PAF, Kroptavich CR, Zhou S, Kahan TF. Oxidant concentrations and photochemistry in a vehicle cabin. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024. [PMID: 39058373 DOI: 10.1039/d4em00319e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Indoor air quality (IAQ) in vehicles can be important to people's health, especially for those whose occupations require them to spend extensive time in vehicles. To date, research on vehicle IAQ has primarily focused on direct emissions as opposed to chemistry happening in vehicle cabins. In this work, we conducted time-resolved measurements of the oxidants and oxidant precursors ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), and nitrous acid (HONO) inside the cabin of a 2012 Toyota Rav4 under varying ventilation conditions (i.e., car off, car on with passive ventilation, car on with mechanical ventilation via the recirculating fan, and car on with mechanical ventilation via the direct fan). Ozone levels inside the vehicle were significantly lower than outdoors under most conditions, and were approximately half the outdoor levels when the direct fan was in operation. Nitric oxide and NO2 concentrations were very low both inside the vehicle and outdoors. Nitrous acid levels in the vehicle were lower than reported values in other indoor environments, though much higher than expected outdoor levels. We also investigated the potential for photochemical production of radicals in the vehicle. Time- and wavelength-resolved solar irradiance spectra were collected, and steady state hydroxyl radical (OH) and nitrate radical (NO3) concentrations were calculated. Steady state OH concentrations were predicted to be similar to those in air masses in residences illuminated by sunlight, suggesting the importance of HONO photolysis in vehicles. Conversely, nitrate radicals (NO3) were not considered significant indoor oxidants in our study due to rapid titration by NO. Overall, our findings emphasize the importance of both air exchange and photochemistry in shaping the composition of air inside vehicles.
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Affiliation(s)
- Pedro A F Souza
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK, Canada.
| | | | - Shan Zhou
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, USA
| | - Tara F Kahan
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK, Canada.
- Department of Chemistry, Syracuse University, Syracuse, NY, USA
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2
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Carter TJ, Shaw DR, Carslaw DC, Carslaw N. Indoor cooking and cleaning as a source of outdoor air pollution in urban environments. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024; 26:975-990. [PMID: 38525871 DOI: 10.1039/d3em00512g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Indoor sources of air pollution, such as from cooking and cleaning, play a key role in indoor gas-phase chemistry. The focus of the impact of these activities on air quality tends to be indoors, with less attention given to the impact on air quality outside buildings. This study uses the INdoor CHEmical Model in Python (INCHEM-Py) and the Advanced Dispersion Modelling System (ADMS) to quantify the impact cooking and cleaning have on indoor and outdoor air quality for an idealised street of houses. INCHEM-Py has been developed to determine the concentrations of 106 indoor volatile organic compounds at the point they leave a building (defined as near-field concentrations). For a simulated 140 m long street with 10 equi-distant houses undertaking cooking and cleaning activities, the maximum downwind concentration of acetaldehyde increases from a background value of 0.1 ppb to 0.9 ppb post-cooking, whilst the maximum downwind chloroform concentrations increase from 1.2 to 6.2 ppt after cleaning. Although emissions to outdoors are higher when cooking and cleaning happen indoors, the contribution of these activities to total UK emissions of volatile organic compounds is low (less than 1%), and comprise about a quarter of those emitted from traffic across the UK. It is important to quantify these emissions, particularly as continued vehicle technology improvements lead to lower direct emissions outdoors, making indoor emissions relatively more important. Understanding how indoor pollution can affect outdoor environments, will allow better mitigation measures to be designed in the future that can take into account all sources of pollution that contribute to human exposure.
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Affiliation(s)
- Toby J Carter
- Department of Environment and Geography, University of York, York, YO10 5NG, UK.
| | - David R Shaw
- Department of Environment and Geography, University of York, York, YO10 5NG, UK.
| | - David C Carslaw
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Nicola Carslaw
- Department of Environment and Geography, University of York, York, YO10 5NG, UK.
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3
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Harding-Smith E, Shaw DR, Shaw M, Dillon TJ, Carslaw N. Does green mean clean? Volatile organic emissions from regular versus green cleaning products. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024; 26:436-450. [PMID: 38258874 DOI: 10.1039/d3em00439b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Cleaning products emit a range of volatile organic compounds (VOCs), including some which are hazardous or can undergo chemical transformations to generate harmful secondary pollutants. In recent years, "green" cleaners have become increasingly popular, with an implicit assumption that these are better for our health and/or the environment. However, there is no strong evidence to suggest that they are better for indoor air quality compared to regular products. In this study, the VOC composition of 10 regular and 13 green cleaners was examined by headspace analysis. Monoterpenes were the most prevalent VOCs, with average total monoterpene concentrations of 8.6 and 25.0 mg L-1 for regular and green cleaners, respectively. Speciated monoterpene emissions were applied to a detailed chemical model to investigate the indoor air chemistry following a typical cleaning event. Green cleaners generally emitted more monoterpenes than regular cleaners, resulting in larger increases in harmful secondary pollutant concentrations following use, such as formaldehyde (up to 7%) and PAN species (up to 6%). However, emissions of the most reactive monoterpenes (α-terpinene, terpinolene and α-phellandrene), were observed more frequently from regular cleaners, resulting in a disproportionately large impact on the concentrations of radical species and secondary pollutants that were formed after cleaning occurred.
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Affiliation(s)
- Ellen Harding-Smith
- Department of Environment and Geography, University of York, UK.
- Department of Chemistry, Wolfson Atmospheric Chemistry Laboratory, University of York, UK
| | - David R Shaw
- Department of Environment and Geography, University of York, UK.
| | - Marvin Shaw
- National Centre for Atmospheric Science, University of York, York, UK
| | - Terry J Dillon
- Department of Chemistry, Wolfson Atmospheric Chemistry Laboratory, University of York, UK
| | - Nicola Carslaw
- Department of Environment and Geography, University of York, UK.
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4
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Davies HL, O'Leary C, Dillon T, Shaw DR, Shaw M, Mehra A, Phillips G, Carslaw N. A measurement and modelling investigation of the indoor air chemistry following cooking activities. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1532-1548. [PMID: 37609942 DOI: 10.1039/d3em00167a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Domestic cooking is a source of indoor air pollutants, including volatile organic compounds (VOCs), which can impact on indoor air quality. However, the real-time VOC emissions from cooking are not well characterised, and similarly, the resulting secondary chemistry is poorly understood. Here, selected-ion flow-tube mass spectrometry (SIFT-MS) was used to monitor the real-time VOC emissions during the cooking of a scripted chicken and vegetable stir-fry meal, in a room scale, semi-realistic environment. The VOC emissions were dominated by alcohols (70% of total emission), but also contained a range of aldehydes (14%) and terpenes (5%), largely attributable to the heating of oil and the preparation and heating of spices, respectively. The direct cooking-related VOC emissions were then simulated using the Indoor Chemical Model in Python (INCHEM-Py), to investigate the resulting secondary chemistry. Modelling revealed that VOC concentrations were dominated by direct emissions, with only a small contribution from secondary products, though the secondary species were longer lived than the directly emitted species. Following cooking, hydroxyl radical concentrations reduced by 86%, while organic peroxy radical levels increased by over 700%, later forming secondary organic nitrates, peroxyacylnitrates (PANs) and formaldehyde. Monoterpene emissions were shown to drive the formation of secondary formaldehyde, albeit to produce relatively modest concentrations (average of 60 ppt). Sensitivity analysis of the simulation conditions revealed that increasing the outdoor concentrations of ozone and NOx species (2.9× and 9×, respectively) resulted in the greatest increase in secondary product formation indoors (≈400%, 200% and 600% increase in organic nitrates, PANs and formaldehyde production, respectively). Given the fact that climate change is likely to result in increased ozone concentrations in the future, and that increased window-opening in response to rising temperatures is also likely, higher concentrations of indoor oxidants are likely in homes in the future. This work, therefore, suggests that cooking could be a more important source of secondary pollutants indoors in the future.
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Affiliation(s)
- Helen L Davies
- Department of Environment and Geography, University of York, Heslington, York, UK.
| | - Catherine O'Leary
- Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, Heslington, York, UK
| | - Terry Dillon
- Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, Heslington, York, UK
| | - David R Shaw
- Department of Environment and Geography, University of York, Heslington, York, UK.
| | - Marvin Shaw
- Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, Heslington, York, UK
| | - Archit Mehra
- Department of Physical, Mathematical and Engineering Sciences, University of Chester, Chester, UK
| | - Gavin Phillips
- Department of Physical, Mathematical and Engineering Sciences, University of Chester, Chester, UK
| | - Nicola Carslaw
- Department of Environment and Geography, University of York, Heslington, York, UK.
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5
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Wang Z, Shaw D, Kahan T, Schoemaecker C, Carslaw N. A modeling study of the impact of photolysis on indoor air quality. INDOOR AIR 2022; 32:e13054. [PMID: 35762241 PMCID: PMC9328129 DOI: 10.1111/ina.13054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/06/2022] [Accepted: 05/06/2022] [Indexed: 05/26/2023]
Abstract
The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper uses recent experimental data to modify a detailed chemical model, using it to investigate the impacts of glass type, artificial indoor lighting, cloudiness, time of year and latitude on indoor photolysis rates and hence indoor air chemistry. Switching from an LED to an uncovered fluorescent tube light increased predicted indoor hydroxyl radical concentrations by ~13%. However, moving from glass that transmitted outdoor light at wavelengths above 380 nm to one that transmitted sunlight above 315 nm led to an increase in predicted hydroxyl radicals of more than 400%. For our studied species, including ozone, nitrogen oxides, nitrous acid, formaldehyde, and hydroxyl radicals, the latter were most sensitive to changes in indoor photolysis rates. Concentrations of nitrogen dioxide and formaldehyde were largely invariant, with exchange with outdoors and internal deposition controlling their indoor concentrations. Modern lights such as LEDs, together with low transmission glasses, will likely reduce the effects of photolysis indoors and the production of potentially harmful species. Research is needed on the health effects of different indoor air mixtures to confirm this conclusion.
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Affiliation(s)
- Zixu Wang
- Department of Environment and GeographyUniversity of YorkYorkUK
| | - David Shaw
- Department of Environment and GeographyUniversity of YorkYorkUK
| | - Tara Kahan
- Department of ChemistryUniversity of SaskatchewanSaskatoonSaskatchewanCanada
| | - Coralie Schoemaecker
- CNRS, UMR 8522 – PC2A – Physicochimie des Processus de Combustion et de l’AtmosphèreUniversité LilleLilleFrance
| | - Nicola Carslaw
- Department of Environment and GeographyUniversity of YorkYorkUK
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6
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Zhou S, Kahan TF. Spatiotemporal characterization of irradiance and photolysis rate constants of indoor gas-phase species in the UTest house during HOMEChem. INDOOR AIR 2022; 32:e12964. [PMID: 34854500 DOI: 10.1111/ina.12966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/20/2021] [Accepted: 11/14/2021] [Indexed: 05/25/2023]
Abstract
We made intensive measurements of wavelength-resolved spectral irradiance in a test house during the HOMEChem campaign and report diurnal profiles and two-dimensional spatial distribution of photolysis rate constants (J) of several important indoor photolabile gases. Results show that sunlight entering through windows, which was the dominant source of ultraviolet (UV) light in this house, led to clear diurnal cycles, and large time- and location-dependent variations in local gas-phase photochemical activity. Local J values of several key indoor gases under direct solar illumination were 1.8-7.4 times larger-and more strongly dependent on time, solar zenith angle, and incident angle of sunlight relative to the window-than under diffuse sunlight. Photolysis rate constants were highly spatially heterogeneous and fast photochemical reactions in the gas phase were generally confined to within tens of cm of the region that were directly sunlit. Opening windows increased UV photon fluxes by 3 times and increased predicted local hydroxyl radical (OH) concentrations in the sunlit region by 4.5 times to 3.2 × 107 molec cm-3 due to higher J values and increased contribution from O3 photolysis. These results can be used to improve the treatment of photochemistry in indoor chemistry models and are a valuable resource for future studies that use the publicly available HOMEChem measurements.
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Affiliation(s)
- Shan Zhou
- Department of Chemistry, Syracuse University, Syracuse, New York, USA
- Department of Civil and Environmental Engineering, Rice University, Houston, Texas, USA
| | - Tara F Kahan
- Department of Chemistry, Syracuse University, Syracuse, New York, USA
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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7
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Zhou S, Kowal SF, Cregan AR, Kahan TF. Factors affecting wavelength-resolved ultraviolet irradiance indoors and their impacts on indoor photochemistry. INDOOR AIR 2021; 31:1187-1198. [PMID: 33373097 DOI: 10.1111/ina.12784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/13/2020] [Accepted: 12/08/2020] [Indexed: 05/25/2023]
Abstract
We measured wavelength-resolved ultraviolet (UV) irradiance in multiple indoor environments and quantified the effects of variables such as light source, solar angles, cloud cover, window type, and electric light color temperature on indoor photon fluxes. The majority of the 77 windows and window samples investigated completely attenuated sunlight at wavelengths shorter than 320 nm; despite variations among individual windows leading to differences in indoor HONO photolysis rate constants (JHONO ) and local hydroxyl radical (OH) concentrations of up to a factor of 50, wavelength-resolved transmittance was similar between windows in residential and non-residential buildings. We report mathematical relationships that predict indoor solar UV irradiance as a function of solar zenith angle, incident angle of sunlight on windows, and distance from windows and surfaces for direct and diffuse sunlight. Using these relationships, we predict elevated indoor steady-state OH concentrations (0.80-7.4 × 106 molec cm-3 ) under illumination by direct and diffuse sunlight and fluorescent tubes near windows or light sources. However, elevated OH concentrations at 1 m from the source are only predicted under direct sunlight. We predict that reflections from indoor surfaces will have minor contributions to room-averaged indoor UV irradiance. These results may improve parameterization of indoor chemistry models.
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Affiliation(s)
- Shan Zhou
- Department of Civil and Environmental Engineering, Rice University, Houston, Texas, USA
| | - Shawn F Kowal
- Department of Chemistry, Syracuse University, Syracuse, New York, USA
| | - Alyssa R Cregan
- Department of Chemistry, Syracuse University, Syracuse, New York, USA
| | - Tara F Kahan
- Department of Chemistry, Syracuse University, Syracuse, New York, USA
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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8
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Wang Z, Kowal SF, Carslaw N, Kahan TF. Photolysis-driven indoor air chemistry following cleaning of hospital wards. INDOOR AIR 2020; 30:1241-1255. [PMID: 32485006 DOI: 10.1111/ina.12702] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/17/2020] [Accepted: 05/19/2020] [Indexed: 05/25/2023]
Abstract
Effective cleaning techniques are essential for the sterilization of rooms in hospitals and industry. No-touch devices (NTDs) that use fumigants such as hydrogen peroxide (H2 O2 ), formaldehyde (HCHO), ozone (O3 ), and chlorine dioxide (OClO) are a recent innovation. This paper reports a previously unconsidered potential consequence of such cleaning technologies: the photochemical formation of high concentrations of hydroxyl radicals (OH), hydroperoxy radicals (HO2 ), organic peroxy radicals (RO2 ), and chlorine radicals (Cl) which can form harmful reaction products when exposed to chemicals commonly found in indoor air. This risk was evaluated by calculating radical production rates and concentrations based on measured indoor photon fluxes and typical fumigant concentrations during and after cleaning events. Sunlight and fluorescent tubes without covers initiated photolysis of all fumigants, and plastic-covered fluorescent tubes initiated photolysis of only some fumigants. Radical formation was often dominated by photolysis of fumigants during and after decontamination processes. Radical concentrations were predicted to be orders of magnitude greater than background levels during and immediately following cleaning events with each fumigant under one or more illumination condition. Maximum predicted radical concentrations (1.3 × 107 molecule cm-3 OH, 2.4 ppb HO2 , 6.8 ppb RO2 and 2.2 × 108 molecule cm-3 Cl) were much higher than baseline concentrations. Maximum OH concentrations occurred with O3 photolysis, HO2 with HCHO photolysis, and RO2 and Cl with OClO photolysis. Elevated concentrations may persist for hours after NTD use, depending on the air change rate and air composition. Products from reactions involving radicals could significantly decrease air quality when disinfectants are used, leading to adverse health effects for occupants.
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Affiliation(s)
- Zixu Wang
- Department of Environment and Geography, University of York, York, UK
| | - Shawn F Kowal
- Department of Chemistry, Syracuse University, Syracuse, NY, USA
| | - Nicola Carslaw
- Department of Environment and Geography, University of York, York, UK
| | - Tara F Kahan
- Department of Chemistry, Syracuse University, Syracuse, NY, USA
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK, Canada
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9
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Bekö G, Carslaw N, Fauser P, Kauneliene V, Nehr S, Phillips G, Saraga D, Schoemaecker C, Wierzbicka A, Querol X. The past, present, and future of indoor air chemistry. INDOOR AIR 2020; 30:373-376. [PMID: 32333696 DOI: 10.1111/ina.12634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 06/11/2023]
Affiliation(s)
- Gabriel Bekö
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Nicola Carslaw
- Department of Environment and Geography, University of York, York, UK
| | - Patrik Fauser
- Department of Environmental Science, Århus University, Roskilde, Denmark
| | - Violeta Kauneliene
- Faculty of Chemical Technology, Kaunas University of Technology, Kaunas, Lithuania
| | - Sascha Nehr
- European University of Applied Sciences, Brühl, Germany
| | - Gavin Phillips
- Faculty of Science and Engineering, University of Chester, Chester, UK
| | - Dikaia Saraga
- National Center for Scientific Research "Demokritos", Athens, Greece
| | - Coralie Schoemaecker
- Physicochimie des Processus de Combustion et de l'Atmosphère, Université Lille, Lille, France
| | - Aneta Wierzbicka
- Devision of Ergonomics and Aerosol Technology, Lund University, Lund, Sweden
| | - Xavier Querol
- Institute of Environmental Assessment and Water Research, Barcelona, Spain
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10
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Huangfu Y, Lima NM, O'Keeffe PT, Kirk WM, Lamb BK, Walden VP, Jobson BT. Whole-House Emission Rates and Loss Coefficients of Formaldehyde and Other Volatile Organic Compounds as a Function of the Air Change Rate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:2143-2151. [PMID: 31898894 DOI: 10.1021/acs.est.9b05594] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Whole-house emission rates and indoor loss coefficients of formaldehyde and other volatile organic compounds (VOCs) were determined from continuous measurements inside a net-zero energy home at two different air change rates (ACHs). By turning the mechanical ventilation on and off, it was demonstrated that formaldehyde concentrations reach a steady state much more quickly than other VOCs, consistent with a significant indoor loss rate attributed to surface uptake. The first order loss coefficient for formaldehyde was 0.47 ± 0.06 h-1 at 0.08 h-1 ACH and 0.88 ± 0.22 h-1 at 0.62 h-1 ACH. Loss rates for other VOCs measured were not discernible, with the exception of hexanoic acid. A factor of 5.5 increase in the ACH increased the whole-house emission rates of VOCs but by varying degrees (factors of 1.1 to 3.8), with formaldehyde displaying no significant change. The formaldehyde area-specific emission rate (86 ± 8 μg m-2 h-1) was insensitive to changes in the ACH because its large indoor loss rate muted the impact of ventilation on indoor air concentrations. These results demonstrate that formaldehyde loss rates must be taken into account to correctly estimate whole-house emission rates and that ventilation will not be as effective at reducing indoor formaldehyde concentrations as it is for other VOCs.
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Affiliation(s)
- Yibo Huangfu
- Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering , Washington State University , Pullman 99164 , Washington , United States
| | - Nathan M Lima
- Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering , Washington State University , Pullman 99164 , Washington , United States
- School of Architecture and Construction Management , Washington State University , Pullman 99164 , Washington , United States
| | - Patrick T O'Keeffe
- Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering , Washington State University , Pullman 99164 , Washington , United States
| | - William M Kirk
- School of Architecture and Construction Management , Washington State University , Pullman 99164 , Washington , United States
| | - Brian K Lamb
- Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering , Washington State University , Pullman 99164 , Washington , United States
| | - Von P Walden
- Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering , Washington State University , Pullman 99164 , Washington , United States
| | - Bertram T Jobson
- Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering , Washington State University , Pullman 99164 , Washington , United States
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11
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Abbatt JPD, Wang C. The atmospheric chemistry of indoor environments. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:25-48. [PMID: 31712796 DOI: 10.1039/c9em00386j] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Through air inhalation, dust ingestion and dermal exposure, the indoor environment plays an important role in controlling human chemical exposure. Indoor emissions and chemistry can also have direct impacts on the quality of outdoor air. And so, it is important to have a strong fundamental knowledge of the chemical processes that occur in indoor environments. This review article summarizes our understanding of the indoor chemistry field. Using a molecular perspective, it addresses primarily the new advances that have occurred in the past decade or so and upon developments in our understanding of multiphase partitioning and reactions. A primary goal of the article is to contrast indoor chemistry to that which occurs outdoors, which we know to be a strongly gas-phase, oxidant-driven system in which substantial oxidative aging of gases and aerosol particles occurs. By contrast, indoor environments are dark, gas-phase oxidant concentrations are relatively low, and due to air exchange, only short times are available for reactive processing of gaseous and particle constituents. However, important gas-surface partitioning and reactive multiphase chemistry occur in the large surface reservoirs that prevail in all indoor environments. These interactions not only play a crucial role in controlling the composition of indoor surfaces but also the surrounding gases and aerosol particles, thus affecting human chemical exposure. There are rich research opportunities available if the advanced measurement and modeling tools of the outdoor atmospheric chemistry community continue to be brought indoors.
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Affiliation(s)
- Jonathan P D Abbatt
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada.
| | - Chen Wang
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada.
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12
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Liu J, Li S, Zeng J, Mekic M, Yu Z, Zhou W, Loisel G, Gandolfo A, Song W, Wang X, Zhou Z, Herrmann H, Li X, Gligorovski S. Assessing indoor gas phase oxidation capacity through real-time measurements of HONO and NO x in Guangzhou, China. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:1393-1402. [PMID: 31322150 DOI: 10.1039/c9em00194h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The hydroxyl radical (OH) is one of the most important oxidants controlling the oxidation capacity of the indoor atmosphere. One of the main OH sources indoors is the photolysis of nitrous acid (HONO). In this study, real-time measurements of HONO, nitrogen oxides (NOx) and ozone (O3) in an indoor environment in Guangzhou, China, were performed under two different conditions: (1) in the absence of any human activity and (2) in the presence of cooking. The maximum NOx and HONO levels drastically increased from 15 and 4 ppb in the absence of human activity to 135 and 40 ppb during the cooking event, respectively. The photon flux was determined for the sunlit room, which has a closed south-east oriented window. The photon flux was used to estimate the photolysis rate constants of NO2, J(NO2), and HONO, J(HONO), which span the range between 8 × 10-5 and 1.5 × 10-5 s-1 in the morning from 9:30 to 11:45, and 8.5 × 10-4 and 1.5 × 10-4 s-1 at noon, respectively. The OH concentrations calculated by photostationary state (PSS) approach, observed around noon, are very similar, i.e., 2.4 × 106 and 3.1 × 106 cm-3 in the absence of human activity and during cooking, respectively. These results suggest that under "high NOx" conditions (NOx higher than a few ppb) and with direct sunlight in the room, the NOx and HONO chemistry would be similar, independent of the geographic location of the indoor environment, which facilitates future modeling studies focused on indoor gas phase oxidation capacity.
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Affiliation(s)
- Jiangping Liu
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510 640, China.
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13
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Young CJ, Zhou S, Siegel JA, Kahan TF. Illuminating the dark side of indoor oxidants. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:1229-1239. [PMID: 31173015 DOI: 10.1039/c9em00111e] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The chemistry of oxidants and their precursors (oxidants*) plays a central role in outdoor environments but its importance in indoor air remains poorly understood. Ozone (O3) chemistry is important in some indoor environments and, until recently, ozone was thought to be the dominant oxidant indoors. There is now evidence that formation of the hydroxyl radical by photolysis of nitrous acid (HONO) and formaldehyde (HCHO) may be important indoors. In the past few years, high time-resolution measurements of oxidants* indoors have become more common and the importance of event-based release of oxidants* during activities such as cleaning has been proposed. Here we review the current understanding of oxidants* indoors, including drivers of the formation and loss of oxidants*, levels of oxidants* in indoor environments, and important directions for future research.
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Affiliation(s)
- Cora J Young
- Department of Chemistry, York University, Canada.
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14
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Zhou S, Young CJ, VandenBoer TC, Kowal SF, Kahan TF. Time-Resolved Measurements of Nitric Oxide, Nitrogen Dioxide, and Nitrous Acid in an Occupied New York Home. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:8355-8364. [PMID: 29973042 DOI: 10.1021/acs.est.8b01792] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Indoor oxidizing capacity in occupied residences is poorly understood. We made simultaneous continuous time-resolved measurements of ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), and nitrous acid (HONO) for two months in an occupied detached home with gas appliances in Syracuse, NY. Indoor NO and HONO mixing ratios were higher than those outdoors, whereas O3 was much lower (sub-ppbv) indoors. Cooking led to peak NO, NO2, and HONO levels 20-100 times greater than background levels; HONO mixing ratios of up to 50 ppbv were measured. Our results suggest that many reported NO2 levels may have a large positive bias due to HONO interference. Nitrous acid, NO2, and NO were removed from indoor air more rapidly than CO2, indicative of reactive removal processes or surface uptake. We measured spectral irradiance from sunlight entering the residence through glass doors; hydroxyl radical (OH) production rates of (0.8-10) × 107 molecules cm-3 s-1 were calculated in sunlit areas due to HONO photolysis, in some cases exceeding rates expected from ozone-alkene reactions. Steady-state nitrate radical (NO3) mixing ratios indoors were predicted to be lower than 1.65 × 104 molecules cm-3. This work will help constrain the temporal nature of oxidant concentrations in occupied residences and will improve indoor chemistry models.
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Affiliation(s)
- Shan Zhou
- Department of Chemistry , Syracuse University , Syracuse , New York 13244 , United States
| | - Cora J Young
- Department of Chemistry , York University , Toronto , Ontario M3J 1P3 , Canada
| | - Trevor C VandenBoer
- Department of Chemistry , York University , Toronto , Ontario M3J 1P3 , Canada
| | - Shawn F Kowal
- Department of Chemistry , Syracuse University , Syracuse , New York 13244 , United States
| | - Tara F Kahan
- Department of Chemistry , Syracuse University , Syracuse , New York 13244 , United States
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