Research ArticleATMOSPHERIC SCIENCE

Surface reservoirs dominate dynamic gas-surface partitioning of many indoor air constituents

See allHide authors and affiliations

Science Advances  19 Feb 2020:
Vol. 6, no. 8, eaay8973
DOI: 10.1126/sciadv.aay8973
  • Fig. 1 Indoor mixing ratios of several acids during EV experiments.

    The top panel shows the measured house temperature (T; left axis), relative humidity (RH; right axis), and absolute humidity (AH; second right axis). Temperature and RH were measured in the kitchen within 1 m of the CIMS inlet. The shaded areas indicate when doors and windows were open to increase the ventilation rate of the house. The hourly 2-min background measurement (measuring zero air) is shown with purple dots, followed by a 5-min outdoor measurement (orange dots). The average air exchange rate (AER) when the house is closed following each EV experiment is summarized in table S2. The color bars at the bottom of the plot show the state of outdoor air supply fan (on/off), window light (with/without), and air conditioning (AC) (on/off) during the experiment, with the green shaded periods showing when the fan, window light, and AC were off.

  • Fig. 2 Box and whisker plot of response time constants.

    Only the first six EV experiments (EV1 to EV6) are shown. Response times for EV7 are not shown due to the significant change of house conditions, i.e., dehumidification associated with air conditioner operation. The horizontal line and the cross symbol inside each box denote the median and the mean, respectively. The top and bottom boundaries of each box show the third and first quartiles. The top and bottom of the vertical line (i.e., the whisker) show the maximum and minimum data points, respectively. The acids were measured with CIMS (acetic acid measured with iodide CIMS and the others measured with acetate CIMS), and the nonacidic compounds were measured with the PTR-TOF-MS, except for NH3, which was measured by cavity ring-down spectroscopy. Data for D5 siloxane in EV1 and EV2 and for acetic acid in EV5 were excluded due to interferences.

  • Fig. 3 Indoor air acid mixing ratios during vinegar and ammonia cleaning.

    AB1 to AB4 represent four acid-base experiments. The shaded areas show when doors and windows were open to enhance house ventilation (blue). Times of mopping the floor with vinegar solution (green) and spraying ammonia on indoor surfaces (pink) are also indicated. Mixing ratios measured in outdoor air and for zero air are denoted by orange and purple dots. The top panel shows the RH and temperature measured in the kitchen. The AC system was turned off during the two ventilation periods.

  • Fig. 4 Partitioning space plots.

    (A) An indoor environment with 1.5 × 10−7 m3 of weakly polar and polar reservoirs each per cubic meter of air, without acid and base dissociation; (B) same volume of polar and weakly polar reservoirs as in (A), but considering acid and base dissociation in the polar reservoir; (C) 7.5 × 10−6 m3 and 1.5 × 10−6 m3 of weakly polar and polar reservoir per cubic meter of air, respectively, with acid and base dissociation; and (D) a highly polluted outdoor environment with 100 mg m–3 each for liquid water and organic content in the ambient aerosol [phase separated into organic (represented by octanol) and water phase (51)], with acid and base dissociation. Names of the individual species are labeled in (A), with C1 to C9 representing monocarboxylic acids with one to nine carbons; their locations shift slightly in (B) and (C) relative to the boundaries, but the ordering does not change. The dashed lines in the space indicate boundaries for different fractions of compounds in each phase, and the blue text shows the fraction in gas versus polar phase for the dashed line below the blue label. The different symbols in (B) to (D) indicate the assumed pH of the polar phase, as indicated in the legend. Note that, in (D), the range of log Kwa and log Koa is expanded to 13, as compared to 10 in (A) to (C).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/8/eaay8973/DC1

    Text S1. Surface nitrite analysis during HOMEChem.

    Text S2. Detrending data and response time calculation.

    Text S3. Phase distribution calculation.

    Text S4. CIMS calibration and data analysis.

    Text S5. PTR-TOF-MS calibration and data analysis.

    Fig. S1. Time-series of different species during EV experiments.

    Fig. S2. Detrending data during the EV experiments.

    Fig. S3. Indoor air signals during vinegar and ammonia cleaning.

    Fig. S4. Comparison of mixing ratios before and during vinegar cleaning.

    Fig. S5. Indoor acetic acid and ammonia mixing ratio during vinegar and ammonia cleaning.

    Fig. S6. Partitioning space plot for an indoor environment.

    Table S1. Physical and chemical properties of different compounds at 25°C.

    Table S2. Time-averaged steady-state mixing ratios (parts per billion).

    Table S3. Vinegar and ammonia cleaning experiment details.

    Table S4. EV experiment details.

    References (5255)

  • Supplementary Materials

    This PDF file includes:

    • Text S1. Surface nitrite analysis during HOMEChem.
    • Text S2. Detrending data and response time calculation.
    • Text S3. Phase distribution calculation.
    • Text S4. CIMS calibration and data analysis.
    • Text S5. PTR-TOF-MS calibration and data analysis.
    • Fig. S1. Time-series of different species during EV experiments.
    • Fig. S2. Detrending data during the EV experiments.
    • Fig. S3. Indoor air signals during vinegar and ammonia cleaning.
    • Fig. S4. Comparison of mixing ratios before and during vinegar cleaning.
    • Fig. S5. Indoor acetic acid and ammonia mixing ratio during vinegar and ammonia cleaning.
    • Fig. S6. Partitioning space plot for an indoor environment.
    • Table S1. Physical and chemical properties of different compounds at 25°C.
    • Table S2. Time-averaged steady-state mixing ratios (parts per billion).
    • Table S3. Vinegar and ammonia cleaning experiment details.
    • Table S4. EV experiment details.
    • References (5255)

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article