Abstract. By using adequate sampling techniques we studied the chemical pathways, the gas-to-particle partition and the conversion processes leading to the formation of organic aerosols via the photo-oxidation of biogenic hydrocarbons in the atmosphere over a conifer forest. Photo-oxidation products of monoterpenes such as pinonic acid, nor-pinonic acid, pinic acid, pinonaldehyde and nopinone were detected in the gas and particulate phases of all forest aerosol samples. Considering the diurnal concentration pattern of the photo-oxidation products of a-and 13-pinene and Aitken nuclei concentration measured during the same periods, we observed that the acidic photo-oxidation products of monoterpenes play a more important role in the formation of new particles than the corresponding carbonyl compounds.'

Pulmonary inflammatory and hematologic responses of canines were studied after exposure to concentrated ambient particles (CAPs) using the Harvard ambient particle concentrator (HAPC). For pulmonary inflammatory studies, normal dogs were exposed in pairs to either CAPs or filtered air (paired studies) for 6 hr/day on 3 consecutive days. For hematologic studies, dogs were exposed for 6 hr/day for 3 consecutive days with one receiving CAPs while the other was simultaneously exposed to filtered air; crossover of exposure took place the following week (crossover studies). Physicochemical characterization of CAPs exposure samples included measurements of particle mass, size distribution, and composition. No statistical differences in biologic responses were found when all CAPs and all sham exposures were compared. However, the variability in biologic response was considerably higher with CAPs exposure. Subsequent exploratory graphical analyses and mixed linear regression analyses suggested associations between CAPs constituents and biologic responses. Factor analysis was applied to the compositional data from paired and crossover experiments to determine elements consistently associated with each other in CAPs samples. In paired experiments, four factors were identified; in crossover studies, a total of six factors were observed. Bronchoalveolar lavage (BAL) and hematologic data were regressed on the factor scores. Increased BAL neutrophil percentage, total peripheral white blood cell (WBC) counts, circulating neutrophils, and circulating lymphocytes were associated with increases in the aluminum/silicon factor. Increased circulating neutrophils and increased BAL macrophages were associated with the vanadium/nickel factor. Increased BAL neutrophils were associated with the bromine/lead factor when only the compositional data from the third day of CAPs exposure were used. Significant decreases in red blood cell counts and hemoglobin levels were correlated with the sulfur factor. BAL or hematologic parameters were not associated with increases in total CAPs mass concentration. These data suggest that CAPs inhalation is associated with subtle alterations in pulmonary and systemic cell profiles, and specific components of CAPs may be responsible for these biologic responses.

[1] Polynuclear aromatic hydrocarbons (PAHs), n-alkanes, n-alkanals, n-alkanols, saturated and unsaturated carboxylic acids, a, w-dicarboxylic acids, and carbonyl and carboxylic photooxidation products of monoteprenes were determined in particle-sized aerosols of urban (Heraclion, Island of Crete, Greece), background marine (Island of Crete, Greece), and forest (Northern Greece and Portugal) atmospheres. The n-alkanes were mostly associated with fine particles in the urban and forest aerosol, and their mass mean aerodynamic diameter (MMAD) calculated over the whole size range (total MMAD) was 0.45 mm and 0.63 mm, respectively. In the background marine aerosol, nalkanes were more evenly distributed, and their MMAD was 2.00 mm, because of physical changes occurring during their long-range transport. Similar observations have been done for PAHs and nalkanals. Conversely, the most biogenic compound class, namely n-alkanols, were evenly associated in the urban, background marine, and forest aerosol, between fine and coarse particles, and their corresponding total MMAD was 2.45, 2.69, and 1.67 mm, respectively. The total MMAD of n-alkanoic acids was 0.71, 0.62, and 0.91 mm in the urban, background marine, and forest aerosol, respectively. Several compounds associated with photochemical reactions in the atmosphere were detected in urban marine and forests aerosol in the fine and ultrafine fraction, showing the low total MMAD (0.28 -0.77 mm) in all aerosol types.

Chile is a fast-growing country with important industrial activities near urban areas. In this study, the mass and elemental concentrations of PM 10 and PM 2.5 were measured in five major Chilean urban areas. Samples of particles with diameter less than 10 µm (PM 10 ) and 2.5 µm (PM 2.5 ) were collected in 1998 in Iquique (northern Chile), Valparaíso, Viña del Mar, Rancagua (central Chile), and Temuco (southern Chile). Both PM 10 and PM 2.5 annual mean concentrations (PM 10 : 56.9-77.6 µg/m 3 ; PM 2.5 : 22.4-42.6 µg/m 3 ) were significantly higher than the corresponding European Union (EU) and U.S. Environmental Protection Agency (EPA) air quality standards. Moreover, the 24-hr PM 10 and PM 2.5 U.S. standards were exceeded infrequently for some of the cities (Rancagua and Valparaíso). IMPLICATIONSA source apportionment study was conducted in five Chilean cities. Both PM 10 and PM 2.5 annual mean concentrations in all five cities were significantly higher than the ambient air quality standards established by the World Health Organization, EU, and the EPA. Consequently, populations residing in these areas are exposed to high particle concentrations that may pose significant health effects. The major sources of coarse particles were soil and sea salt particles. Sources of fine particle mass included automobiles, wood and agricultural waste burning, Cu smelters, and oil refineries. The use of multivariate statistical methods on PM 10 and PM 2.5 mass and elemental concentrations provides information on their sources. The results of these studies can be used to assess the risk of air pollution and to develop cost-effective control strategies.

Users of electronic cigarettes (e-cigs) are exposed to particles and other gaseous pollutants. However, major knowledge gaps on the physico-chemical properties of such exposures and contradictory data in published literature prohibit health risk assessment. Here, the effects of product brand, type, e-liquid flavoring additives, operational voltage, and user puffing patterns on emissions were systematically assessed using a recently developed, versatile, e-cig exposure generation platform and state-of-the-art analytical methods. Parameters of interest in this systematic evaluation included two brands (A and B), three flavors (tobacco, menthol, and fruit), three types of e-cigs (disposable, pre-filled, and refillable tanks), two puffing protocols (4 and 2 s/puff), and four operational voltages (2.2-5.7 V). Particles were generated at a high number concentration (10-10 particles/cm). The particle size distribution was bi-modal (∼200 nm and 1 µm). Furthermore, organic species (humectants propylene glycol and glycerin, nicotine) that were present in e-liquid and trace metals (potassium and sodium) that were present on e-cig heating coil were also released into the emission. In addition, combustion-related byproducts, such as benzene and toluene, were also detected in the range of 100-38,000 ppbv/puff. Parametric analyzes performed in this study show the importance of e-cig brand, type, flavor additives, user puffing pattern (duration and frequency), and voltage on physico-chemical properties of emissions. This observed influence is indicative of the complexity associated with the toxicological screening of emissions from e-cigs and needs to be taken into consideration.

The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5 % of particle mass for particles with δp > 0.96 μm and 10 % of particle mass for particles with δp < 0.96 μm. Non-exchangeable aliphatic (H–C), unsaturated aliphatic (H–C–C=), oxygenated saturated aliphatic (H–C–O), acetalic (O–CH–O) and aromatic (Ar–H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m−3 for particles with 1.5 < δp < 3.0 μm to 73.9 ± 12.3 nmol m−3 for particles with δp < 0.49 μm. The molar H/C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R–H was the most abundant group, representing about 45 % of measured total non-exchangeable organic hydrogen concentrations, followed by H–C–O (27 %) and H–C–C= (26 %). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from −26.81 ± 0.18 ‰ for the smallest particles to −25.93 ± 0.31 ‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with δp > 3.0 μm and δp < 0.96 μm.

This paper presents the design and development of a compact high volume cascade impactor (HVCI).The HVCI operates at a ow rate of 900 l/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup lter. The backup lter is placed downstream of the fourth stage and is used to collect the ultra ne particles (d p < 0.1 ¹m). The major feature of this novel sampler is its ability to collect relatively large amounts of particles (mg-g levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected particles per cm 2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found not to be signi cant. Particles can be easily recovered from the foam substrates using aqueous extraction. The impactor was calibrated using polydisperse particles. The 50% cutpoints of the 4 stages were 9.90, 2.46, 1.0, and 0.1 ¹m, respectively. Interstage losses of ultra ne and ne particles were <10% and for coarse particles were <20%. The pressure drop across the 4 stages and the backup lter were 0.25, 0.75, 1.25, 19.9, and 3.3 kPa, respectively.

A low-cutoff, high-volume conventional impactor has been designed. This sampler uses a slitshaped acceleration jet and operates at 1100 L/ min. The impaction substrate is polyurethane foam ( PUF) . The impactor collection ef ciency was characterized using polydisperse particles, and the 50% size cutoff point was 0.12 m m. Losses within the sampler were also characterized and were less than 10%. The use of polyurethane foam ( PUF) as a substrate has the following advantages: ( 1) PUF has a very high particle collection ef ciency over a large range of particle sizes, even under conditions of heavy particle loading, as compared to other impaction substrates, such as at plates and less porous membranes, which typically are subject to signi cant bounce-off and reentrainment; (2) no oil or grease coating is required, so potential interferences of impurities within such coatings are avoided when chemical, biological, and toxicological tests are performed on the collected particles; ( 3) PUF itself is chemically inert, minimizing interference with any of these tests; ( 4) because of the high ow rate of 1100 L/ min, a large amount of particles can be collected in a short period of time on a relatively small surface of substrate, facilitating recovery of the collected particles for the different tests; and ( 5) a large amount of particles can be collected on a relatively small collection surface and easily extracted with small amounts of water or organic solvents. This method will be suitable for the collection of large amounts for toxicological studies and analysis of organic aerosols, which is not possible with other high-volume samplers that utilize large ltration surfaces.