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Building insulation materials can affect indoor air by (i) releasing primary volatile organic compounds (VOCs) from building enclosure cavities to the interior space, (ii) mitigating exposure to outdoor pollutants through reactive deposition (of oxidants, e.g. , ozone) or filtration (of particles) in infiltration air, and (iii) generating secondary VOCs and other gas-phase byproducts resulting from oxidant reactions. This study reports primary VOC emission fluxes, ozone (O 3 ) reaction probabilities ( γ ), and O 3 reaction byproduct yields for eight common, commercially available insulation materials. Fluxes of primary VOCs from the materials, measured in a continuous flow reactor using proton transfer reaction-time of flight-mass spectrometry, ranged from 3 (polystyrene with thermal backing) to 61 (cellulose) μmol m −2 h −1 (with total VOC mass emission rates estimated to be between ∼0.3 and ∼3.3 mg m −2 h −1 ). Major primary VOC fluxes from cellulose were tentatively identified as compounds likely associated with cellulose chemical and thermal decomposition products. Ozone-material γ ranged from ∼1 × 10 −6 to ∼30 × 10 −6 . Polystyrene with thermal backing and polyisocyanurate had the lowest γ , while cellulose and fiberglass had the highest. In the presence of O 3 , total observed volatile byproduct yields ranged from 0.25 (polystyrene) to 0.85 (recycled denim) moles of VOCs produced per mole of O 3 consumed, or equivalent to secondary fluxes that range from 0.71 (polystyrene) to 10 (recycled denim) μmol m −2 h −1 . Major emitted products in the presence of O 3 were generally different from primary emissions and were characterized by yields of aldehydes and acetone. This work provides new data that can be used to evaluate and eventually model the impact of “hidden” materials ( i.e. , those present inside wall cavities) on indoor air quality. The data may also guide building enclosure material selection, especially for buildings in areas of high outdoor O 3 .
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Closing the Reactive Carbon Flux Budget: Observations From Dual Mass Spectrometers Over a Coniferous Forest
Abstract We use observations from dual high‐resolution mass spectrometers to characterize ecosystem‐atmosphere fluxes of reactive carbon across an extensive range of volatile organic compounds (VOCs) and test how well that exchange is represented in current chemical transport models. Measurements combined proton‐transfer reaction mass spectrometry (PTRMS) and iodide chemical ionization mass spectrometry (ICIMS) over a Colorado pine forest; together, these techniques have been shown to capture the majority of ambient VOC abundance and reactivity. Total VOC mass and associated OH reactivity fluxes were dominated by emissions of 2‐methyl‐3‐buten‐2‐ol, monoterpenes, and small oxygenated VOCs, with a small number of compounds detected by PTRMS driving the majority of both net and upward exchanges. Most of these dominant species are explicitly included in chemical models, and we find here that GEOS‐Chem accurately simulates the net and upward VOC mass and OH reactivity fluxes under clear sky conditions. However, large upward terpene fluxes occurred during sustained rainfall, and these are not captured by the model. Far more species contributed to the downward fluxes than are explicitly modeled, leading to a major underestimation of this key sink of atmospheric reactive carbon. This model bias mainly reflects missing and underestimated concentrations of depositing species, though inaccurate deposition velocities also contribute. The deposition underestimate is particularly large for assumed isoprene oxidation products, organic acids, and nitrates—species that are primarily detected by ICIMS. Net ecosystem‐atmosphere fluxes of ozone reactivity were dominated by sesquiterpenes and monoterpenes, highlighting the importance of these species for predicting near‐surface ozone, oxidants, and aerosols.
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- Award ID(s):
- 1932771
- PAR ID:
- 10433915
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 128
- Issue:
- 14
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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