Factors affecting the indoor concentrations of carbonaceous aerosols of outdoor origin

Abstract

A field study was conducted in an unoccupied single story residence in Clovis, California to provide data to address issues important to assess the indoor exposure to particles of outdoor origin. Measurements of black and organic carbonaceous aerosols were performed using a variety of methods, resulting in both near real-time measurements as well as integrated filter based measurements. Comparisons of the different measurement methods show that it is crucial to account for gas phase adsorption artifacts when measuring organic carbon (OC). Measured concentrations affected by the emissions of organic compounds sorbed to indoor surfaces imply a higher degree of infiltration of outdoor organic carbon aerosols into the indoor environment for our unoccupied house. Analysis of the indoor and outdoor data for black carbon (BC) aerosols show that, on average, the indoor concentration of black carbon aerosols behaves in a similar manner to sulfate aerosols. In contrast, organic carbon aerosols are subject to chemical transformations indoors that, for our unoccupied home, resulted in lower indoor OC concentrations than would be expected by physical loss mechanisms alone. These results show that gas to particle partitioning of organic compounds, as well as gas to surface interactions within the residence, are an important process governing the indoor concentration to OC aerosols of outdoor origin. *

Indoor and Outdoor Particle Number and Mass Concentrations in Athens. Sources, Sinks and Variability of Aerosol Parameters

“…The measured values were typical of urban sites affected by traffic (Hitzenberger and Tohno, 2001;Vianna et al, 2007). Indoor concentration levels were somewhat lower than the respective outdoor levels (24-hr mean values equal to 2.4 ± 1.2 μg/m 3 during the warm period and 2.6 ± 1.0 μg/m 3 during the cold period), indicating that outdoor anthropogenic combustion sources are also the primary source of indoor BC (Lunden et al, 2008).…”

Variability in the fraction of ambient fine particulate matter found indoors and observed heterogeneity in health effect estimates

“…At an AER of 0.45 h À1 , ambient particulate nitrate indoors was only 12% of its outdoor concentration; in contrast, F was 0.67 Outdoor and indoor concentrations of ambient PM 2.5 and the fraction of outdoor PM 2.5 that penetrates and persists indoors (F) for the scenarios described in Figure 1 and (Figure 3) are in agreement with the range of F values reported by several studies (F ¼ 0.32--0.8). 36 Sarnat et al 42 and Lunden et al 43 The model showed little sensitivity to changes in k dep with variations in species-specific size distributions across season and location; it was more sensitive to changes in P filter . The overall F value for scenario (a: NE composition) did not change when k dep values fit based on the Fresno species-specific size distributions were used rather than the New York City size distributions.…”

“…A limitation of this method is that organic PM 2.5 is treated as non-volatile, when in fact it is semivolatile. 46 Sampling studies have demonstrated that phase changes of organics can impact F. Lunden et al 43 concluded that a lower F for OC (F ¼ 0.5) than for EC (F ¼ 0.61) in an unoccupied home was because of evaporation of some particulate OM as organic gases sorbed to indoor surfaces. However, it has also been suggested that ambient OM shifts from the gas phase into the particle phase by sorption into indoor-generated PM in occupied homes.…”

A Pilot Investigation of PM Indoor/Outdoor Mass Concentration and Chemical Analysis during a Period of Extensive Fireplace Use in Athens

“…Though, it should be noted that differences in particle chemical composition exist even between ambientgenerated particles that have infiltrated indoors and their corresponding ambient particles. As Diapouli et al (2013b) reports, this may be attributed to the physical loss mechanisms influencing the infiltration of particles of different sizes, as well as chemical transformations affecting specific PM constituents, such as changes in gas-to-particle partitioning during the infiltration of organic compounds, NO 3 -or ΝΗ 4 + (Hering et al, 2007;Lunden et al, 2008). The ionic balance, as mole equivalence, can be a useful tool to determine possible missing ionic species (Table S2) (Kocak et al, 2007).…”