Diurnal and seasonal variability in size-dependent atmospheric deposition fluxes of polycyclic aromatic hydrocarbons in an urban center

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

“…Table 1 Measured concentrations (C, pg/m 3 ) of individual and total PAHs (sum of the 16 priority PAHs), toxicity equivalency factors (TEFs) (Nisbet and LaGoy, 1992), and concentrations of benzo(a)pyrene equivalent (BaPE) in the indoor air of urban Guangzhou. Predominant mass fractions of PAHs in the accumulation mode particles were also reported previously in the urban atmosphere of Guangzhou (Duan et al, 2007;Zhang et al, 2012), roadside and suburban atmosphere of Saitama City in Japan (Kawanaka et al, 2009), and the urban, mountain and marine atmospheres over East Asia . Source diagnostics based on several PAH isomeric ratios (Supplementary material) indicated that indoor particulate PAHs were mainly derived from fossil fuel combustion such as automobile exhaust.…”

“…Our mean ∑ 12 PAH was similar to the total concentrations in woodburning homes in Hagfors (average 23.6 ng/m 3 , n = 10) (Gustafson et al, 2008), but lower than those in ambient air of Guangzhou (25.4-124 ng/m 3 ) (Duan et al, 2005). In addition, the mean particulate concentration (14.5 ng/m 3 ) of seven PAHs (sum of benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-c,d)pyrene, and benzo(g,h,i)perylene; ∑ 7 PAH) was significantly higher than that in ambient atmosphere at heights of 100 m (daytime: 2.3 ng/m 3 ; night: 3.1 ng/m 3 ) and 150 m (daytime: 2.5 ng/m 3 ; night: 3.6 ng/m 3 ) above ground level in urban Guangzhou during August 2010 (Zhang et al, 2012).…”

“…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.…”

“…For outdoor ambient air, even size distributions of benz(a)anthracene and chrysene in the ambient air of Guangzhou were observed at the height of 100 m above the ground in the daytime of August 2010, but unimodal distributions were obtained in December 2010 (Zhang et al, 2012). The seasonal difference was attributed to volatilization and condensation, which are highly affected by ambient temperature (Zhang et al, 2012).…”

“…Analytical procedures have been given in our previous studies (Zhang et al, , 2012. Concentrations of PAHs were determined with a Shimadzu GC/MS-QP2010 equipped with a 60 m × 0.25 mmi.d.…”