Measurement of Polycyclic Aromatic Hydrocarbons Associated with Size-Segregated Atmospheric Aerosols in Massachusetts

Abstract

Size-segregated atmospheric aerosols were collected from urban and rural locations in Massachusetts using a micro-orifice impactor. The samples were analyzed for polycyclic aromatic hydrocarbons (PAH) with molecular weights between 178 and 302, using gas chromatography/mass spectrometry. Fifteen PAH were quantified in the urban samples and nine in the rural samples. The quantification results are in good agreement with available ambient monitoring data. In the urban samples, PAH were distributed among aerosol size fractions based on molecular weight. PAH with molecular weights between 178 and 202 were approximately evenly distributed between the fine (aerodynamic diameter <2 μm) and coarse (aerodymanic diameter >2 μm) aerosols. PAH with molecular weights greater than 228 were associated primarily with the fine aerosol fraction. In the rural samples, low and high molecular weight PAH were associated with both the fine and coarse aerosols. Slow mass transfer by vaporization and condensation is proposed to explain the observed PAH partitioning among aerosol size fractions.

Calculated respiratory exposure to indoor size-fractioned polycyclic aromatic hydrocarbons in an urban environment

“…S2). Different size distribution patterns for PAHs with various P L were also observed in the ambient atmosphere of Massachusetts (Allen et al, 1996), Los Angeles (Miguel et al, 2004), and Guangzhou at 100 m above the ground in August 2010 (Zhang et al, 2012), which was attributed to the different rates of migration from fine particles to coarse particles via volatilization and condensation for PAHs. Obviously, it is more difficult for PAHs with lower vapor pressures to undergo volatilization and condensation compared to PAHs with higher vapor pressures.…”

“…Particle samples were segregated in size fractions of >18, 10-18, 5.6-10, 3.2-5.6, 1.8-3.2, 1.0-1.8, 0.56-1, 0.32-0.56, 0.18-0.32, 0.10-0.18, 0.056-0.10, and b0.056 μm D p at an airflow rate of 30 L/min. Similar sizesegregated sampling methods have been used in previous studies (Allen et al, 1996;Kawanaka et al, 2009;Venkataraman et al, 1994). Overall, six sets of samples were collected, each for a 48-h period.…”

Seasonal variation of particle size distributions of PAHs at Seoul, Korea

“…Therefore, PAHs tend to remain to fine particles under a low-ambient temperature condition and at sites close from emission sources. In addition, PAHs size distributions in the atmosphere are influenced by the growth of combustion-generated particles and the variation of PAHs adsorption and absorption affinity based on particle size-dependent physical characteristics and chemical composition (Venkataraman and Friedlander 1994;Allen et al 1996).…”

“…Particle size distributions of PAHs have been mainly studied in Europe and North America (Offenberg and Baker 1999; Allen et al 1996;Venkataraman and Friedlander 1994;Aceves and Grimalt 1993;Sicre et al 1987;Miguel and Friedlander 1978;van Vaeck and van Cauwenberghe 1978;Pierce and Katz 1975). In these studies, PAH were predominantly associated with fine particle (D p <2.5 μm), and PAH compounds with the same MW were generally observed in the similar particle size range.…”

Measurements of semivolatile and particulate polycyclic aromatic hydrocarbons in a bus station and an urban tunnel in Salvador, Brazil

“…9 The particulate PAHs measured in urban air and in roadway tunnels have been found in the respirable size range. 6,[10][11][12][13] PAHs are regarded as priority pollutants by both the United States Environmental Protection Agency and the European Community. While no standard currently exists in Brazil for PAH concentrations in ambient air, the UK Government Expert Panel on Air Quality Standards is considering an air quality standard for benzo(a)pyrene of 0.25 ng m 23 .…”