Real‐time transformation of outdoor aerosol components upon transport indoors measured with aerosol mass spectrometry

Abstract

Outdoor aerosols are transported indoors, where their component concentrations depend on aerosol size, physiochemical properties, indoor sources and losses, and cross-environment gradients of temperature and relative humidity. We explored these dependencies by measuring real-time outdoor and indoor non-refractory, submicron (PM ) aerosol component mass concentrations in a mixed-use laboratory space with an Aerodyne mini-aerosol mass spectrometer (AMS) and black carbon (BC) with an aethalometer. The median indoor/outdoor (I/O) ratios were 0.60 for sulfate, 0.25 for nitrate, 0.52 for ammonium, 0.73 for organics, and 0.61 for BC. Positive matrix factorization (PMF) on organic aerosol data identified hydrocarbon-like (HOA), cooking (COA), and oxygenated (OOA) factors. By assuming sulfate was nonvolatile, lost only by mechanical processes, and without indoor sources, the transformations of other components i due to partitioning changes or indoor sources were parameterized by normalizing their I/O ratios by sulfate's I/O ratio, that is, (I/O) . Component-specific behavior was quantified by regressions of (I/O) to outdoor-to-indoor temperature differences. Nitrate and HOA strongly and OOA weakly showed losses with increasing temperatures indoors vs. outdoors, and HOA likely had an indoor source. To our knowledge, this is the first reported deployment of an AMS to analyze real-time indoor aerosol composition and outdoor-to-indoor transformation.

Indoor air quality in schools of a highly polluted south Mediterranean area

“…4 Multidisciplinary reports about indoor measurements in heavily polluted areas on health-relevant chemical and physical properties are still scanty. 7,8 Particularly in very polluted areas, such as industrial sites or urban areas of developing countries, indoor air may reflect the poor quality of the outdoor atmosphere, and domestic and school environments, where urban populations-and children in particular-typically spend up to 90% of their time, thus requiring special attention. 7,8 Particularly in very polluted areas, such as industrial sites or urban areas of developing countries, indoor air may reflect the poor quality of the outdoor atmosphere, and domestic and school environments, where urban populations-and children in particular-typically spend up to 90% of their time, thus requiring special attention.…”

Chemical composition of outdoor and indoor PM2.5collected during haze events: Transformations and modified source contributions resulting from outdoor-to-indoor transport

“…In contrast, increasing the concentration of gaseous OM in normal indoor environments is expected to influence the concentration of particle‐phase OM in the opposite manner to increases in temperature. This would favor a shift in the concentration of OM from a gaseous to a particle phase . Recent studies indicate that organic particles could absorb liquid, semisolid, or glassy states and then influence multiphase chemistry substantially.…”

Ultrafine and Fine Particulate Matter Inside and Outside of Mechanically Ventilated Buildings

“…The AMS has been described in detail elsewhere [23,24]. For the particular AMS used in this experiment, the sample flow rate is restricted by a critical orifice inlet with a diameter of 100 μm, providing a flow of 85 cm 3 ·min −1 .…”