Sources of Gas-Phase Species in an Art Museum from Comprehensive Real-Time Measurements
Abstract
Indoor air at the University of Colorado Boulder art museum was measured by two real-time chemical ionization mass spectrometers (CIMS; iodide and nitrate reagent ions) and a proton transfer reaction mass spectrometer (PTR-MS). Positive Matrix Factorization (PMF) analysis isolated nine different factors for the indoor air composition. Three of these factors were observed by each instrument, and composed over 30% of the organic carbon fraction of each instrument. One factor correlated with carbon dioxide (CO 2 ), indicating a clear influence from human occupancy, another was dominated by small carboxylic acids and likely related to both human occupancy and materials within the building. The third factor was dominated by HONO and ethylene glycol, with strong emission signatures after gallery painting. Additional factors correlated with ozone (O 3 ) and nitrogen dioxide (NO 2 ) and are suggestive of indoor surface reaction products from outdoor-related oxidants. Outdoor-related factors contributed 25-49% of the measured organic carbon fraction. Organic nitrogen compounds were measured and found to correlate with the estimated nitrate radical (NO 3 ). The volatility distribution of each factor by instrument showed higher volatility factors for PTR-MS, intermediate volatility factors for I-CIMS highlighted by small acids, and lower volatility factors for NO 3 -CIMS highlighted by organic nitrate compounds. The carbon oxidation state (OSc) increased within factors from reduced in PTR-MS to oxidized in NO 3 -CIMS, and showed variation among the factors. Each of the PTR-MS factors contributed a substantial portion (3-31%) of the total oxidant-VOC reactivity per oxidant. The majority of the VOC reactivity was contributed by indoor-related factors (52-77%) for all oxidants except O 3 (44%). Human occupancy increased the reactivity of the human (x14), small acids (x1.5), terpenes (x2), and acetone (x5) factors. NO 3 radical reaction with VOCs contributed up to 50% of the reactive flux in the PTR-MS factors, while OH dominated the reactive flux (90%) in the CIMS-only factors. The lifetime of reactivity for each oxidant among all factors was greater than the museum ventilation timescale, showing that reactivity from indoor sources is largely consumed outdoors.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA184.0015P
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 9810 New fields (not classifiable under other headings);
- GENERAL OR MISCELLANEOUS;
- 0240 Public health;
- GEOHEALTH