Functional group characterization of indoor, outdoor, and personal PM2.5: results from RIOPA

Abstract

To our knowledge this is the first time that FTIR spectroscopy has been used to characterize the composition of indoor and personal PM(2.5). The presence of sulfate, nitrate, ammonium, soil dust and a number of organic functional groups are all detected in one analysis on filter samples without extraction or other sample preparation. Differences between indoor and outdoor spectra are used to identify spectral features due to indoor-generated PM(2.5). Particularly interesting are the much larger aliphatic absorbances, shifts in carbonyl absorbances, and occasional small amide absorbances found in indoor and personal spectra but rarely in outdoor spectra. These observations are important because organics make up a large portion of PM(2.5) mass and their composition and properties are poorly characterized. The properties and behavior of organic compounds in airborne particles are often predicted based on their functional group composition. This analysis begins the development of a better understanding of the functional group composition of indoor and personal PM(2.5) and how it differs from that of outdoor PM(2.5). Eventually this will lead to an improved understanding of the properties, behavior and effects of PM(2.5) of indoor and outdoor origin.

Fine organic particulate matter dominates indoor-generated PM2.5 in RIOPA homes

“…Ho et al (2004) also found higher OC/EC ratios indoors (mean OC/EC ¼ 2.7) than outdoors (mean OC/EC ¼ 2.0) in Hong Kong. Additional evidence of indoor-generated organic PM is provided by Reff et al (2005), who found that Fourier transform infrared (FTIR) absorbances attributed to aliphatic hydrocarbon and amide functional groups were enhanced in most indoor RIOPA samples relative to absorbances in concurrently collected outdoor samples. Indoors, particulate OC can be emitted directly in the particle phase (i.e., primary) from sources including cooking, and can be formed in indoor air (i.e., secondary) as a result of reactions involving gas-phase organic compounds and ozone (Weschler and Shields, 1997;Fan et al, 2003;Nazaroff and Weschler, 2004;Weschler, 2004).…”

Organic PM2.5: Fractionation by Polarity, FTIR Spectroscopy, and OM/OC Ratio for the Pittsburgh Aerosol

“…(Spectra shown were selected as representative of these seasons based on visual examination of all spectra.) Because these are spectra of organic extracts, the sharp peaks representing organic functional groups are not masked by the broad ammonium and sulfate absorbances seen in direct FTIR spectroscopic analyses of particles (e.g., Blando et al 1998;Reff et al 2005). The only inorganic functional groups present were nitrate (∼830; 1340-1410 cm −1 ) and ammonium (∼1410-1445; 3030-3052 cm −1 ).…”

“…Amides have also been reported in FTIR spectra of residential indoor and personal exposure PM 2.5 samples . Emissions from cooking and biomass burning are major sources of amides in indoor and outdoor environments (Simoneit et al 2003;He et al 2004;Reff et al 2005).…”

“…Organic PM 2.5 has been characterized in several locations by functional group [FTIR spectroscopy: e.g., Allen et al 1994;Russell, 2003;Reff et al 2005; Nuclear Magnetic Resonance (NMR) spectroscopy: e.g., Graham et al 2002;Tagliavini et al 2006], degree of oxygenation [factor analysis of aerosol mass spectra providing hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) fractions: e.g., Zhang et al 2005] and by polarity [extraction and sometimes column separation: e.g., Gundel et al 1995;Gogou et al 1998]. This article characterizes organic PM 2.5 in Pittsburgh, PA, using a 234 A. POLIDORI ET AL.…”

Comparison of Emissivity, Transmittance, and Reflectance Infrared Spectra of Polycyclic Aromatic Hydrocarbons with those of Atmospheric Particulates (PM1)

“…The signature molecular vibrations from the spectra were identified by comparison with the spectral database (Semmler et al, 1991;Allen et al, 1994;Carrasco Flores et al, 2005;Reff et al, 2005;Onchoke et al, 2006; The molecular vibrations of transmittance spectra were identified from the literature (Semmler et al, 1991;Carrasco Flores et al, 2005;Onchoke et al, 2006;Onchoke and Parks, 2011).…”