Size-resolved particle oxidative potential in the office, laboratory, and home: Evidence for the importance of water-soluble transition metals.

Particulate matter (PM) oxidative potential (OP) is an emerging health metric, but studies examining the OP of indoor PM are rare. This paper focuses on the relationships between respiratory exposure to OP and PM water-soluble composition in indoor environments. Size-resolved PM samples were collected between November 2015 and June 2016 from an office, home (including bedroom, living room, and storeroom), and laboratory using a MOUDI sampler. Particles from each source were segregated into eleven size bins, and the water-soluble metal content and dithiothreitol (DTT) loss rate were measured in each PM extract. The water-soluble OP (OPws) of indoor PM was highest in the office and lowest in the home, varying by factors of up to 1.2; these variations were attributed to differences in occupation density, occupant activity, and ventilation. In addition, the particulate Cu, Mn, and Fe concentrations were closely correlated with OPws in indoor particles; the transition metals may have acted as catalysts during oxidation processes, inducing ·OH formation through the concomitant consumption of DTT. The OPws particle size distributions featured single modes with peaks between 0.18 and 3.2 µm across all indoor sites, reflecting the dominant contribution of PM3.2 to total PM levels and the enhanced oxidative activity of the PM3.2 compared to PM>3.2. Lung-deposition model calculations indicated that PM3.2 dominated the pulmonary deposition of the OPws (>75%) due to both the high levels of metals content and the high deposition efficiency in the alveolar region. Therefore, because OPws has been directly linked to various health effects, special attention should be given to PM3.2.

Distribution and source of alkyl polycyclic aromatic hydrocarbons in dustfall in Shanghai, China: the effect on the coastal area.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are a group of persistent organic pollutants which are widely distributed in the atmospheric environment. To estimate the seasonal and spatial distribution of APAHs in dustfall in Shanghai, supercritical fluid extraction (SFE) followed by gas chromatography/mass spectrometry (GC/MS) were the analytical methods applied to the dustfall samples collected in this area from Dec. 2004 to Oct. 2005. Forty-one APAHs were found and divided into six groups which were alkyl naphthalenes (ANAs), alkyl phenanthrenes (APHs), alkyl anthracenes (AANs), alkyl fluoranthenes (AFLs), alkyl pyrenes (APYs) and alkyl chrysenes (ACHs). ANAs and APHs were two dominant APAHs in the proportion of more than 50%. The concentrations of total APAHs ranged from 1.6 to 9.0 microg g(-1). The ratios of APAHs to TPAHs (PAHs plus APAHs) fell into the range of 28 approximately 50%. The APAH levels were found to be higher in winter and spring than in summer and autumn. In terms of spatial distribution, concentration of APAHs was found to be higher in western Shanghai than eastern Shanghai. The source analysis showed that dustfall APAHs mainly derived from vehicle emissions and used crankcase oil. The annual fluxes of APAHs and PAHs in dustfall in urban Shanghai were 0.53 approximately 2.97 T and 0.96 approximately 5.34 T, respectively.

Determination of alkyl polycyclic aromatic hydrocarbons in dustfall by supercritical fluid extraction followed by gas chromatography/mass spectrum.

A method of supercritical fluid extraction (SFE) followed by gas chromatography/mass spectrum was developed for the determination of alkyl polycyclic aromatic hydrocarbons (APAHs) in dustfall. Extraction parameters including pressure, temperature and time were optimized by orthogonal experimental design. Recovery fell into the range of 73.6%-105.0%, and was prior to the efficiency of ultrasonic extraction. Forty-one 2-4-ring APAHs homologues were detected from dustfall samples. The concentrations of total APAHs were about 2 microg g(-1). The ratios of APAHs/TPAHs (PAHs + APAHs) altered from 19.8% to 24.8%. Source analysis indicated that APAHs originated from combustion.

Determination of PAHs in dust from Shanghai by optimized SFE and GC/MS.

EPA 16 priority polycyclic aromatic hydrocarbons (PAHs) were extracted from dust by supercritical fluid extraction (SFE). Parameters (pressure, temperature and time) affecting the collection efficiencies of PAHs were assessed according to the extraction efficiency, and 30 MPa, 80 degrees C and 30 min dynamic extraction time were confirmed to be the best and simplest conditions of SFE to extract 16 priority PAHs from dust. The characterization of the extracts was carried out by gas chromatography with mass detector in selective ion mode (GC/MS/SIM). Ultrasonic extraction (USE) was used as a comparison with SFE. The results showed that the SFE method has a better efficiency than USE for the extraction of PAHs in dust. With the optimized conditions of SFE, the distribution of PAHs in dust samples in urban areas of Shanghai from Mar 10, 2005 to May 28, 2005 was investigated. The results demonstrated that traffic emission, especially from gasoline engines, was the main source of PAHs in dust of Shanghai.