Seasonal variation in chemical composition of size-segregated urban air particles and the inflammatory activity in the mouse lung.

We investigated the seasonal variations in the chemical composition and in vivo inflammatory activity of urban air particulate samples in four size ranges (PM(10-2.5), PM(2.5-1), PM(1-0.2), and PM(0.2)). The samples were collected in Helsinki using a high-volume cascade impactor (HVCI). Healthy C57BL/6J mice were intratracheally instilled with a single dose (10 mg/kg) of the particulate samples. The lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6, and keratinocyte-derived chemokine [KC]) at 4 h, and total cell number and total protein concentration at 12 h. The PM(10-2.5) and PM(2.5-1) samples had much higher inflammatory potency than the PM(1-0.2) and PM(0.2) samples. The relative inflammatory activities of the autumn samples were the highest on an equal mass basis, but when estimated for the particulate mass per cubic meter of air, the springtime samples had the highest inflammatory potential. Resuspended soil material and other non-exhaust particulate material from traffic were associated with a high inflammatory activity of the PM(10-2.5) and PM(2.5-1) samples. Secondary inorganic ions in the PM(1-0.2) and PM(0.2) samples had inconsistent negative or positive correlations with the inflammatory activity. There were no systematic seasonal variations in the tracers of incomplete combustion and atmospherically oxidized organics in the PM(1-0.2) and PM(0.2) samples, which probably explains their low correlations with the inflammatory activity. In conclusion, in a relatively clean Nordic city, the resuspension of road dust and other non-exhaust particulate material from traffic were the major sources of inflammatory activity of urban air inhalable particles.

Inflammation and tissue damage in mouse lung by single and repeated dosing of urban air coarse and fine particles collected from six European cities.

The authors have previously demonstrated heterogeneities in the inflammatory activities of urban air fine (PM(2.5-0.2)) and coarse (PM(10-2.5)) particulate samples collected from six European cities with contrasting air pollution situations. The same samples (10 mg/kg) were intratracheally instilled to healthy C57BL/6J mice either once or repeatedly on days 1, 3, and 6 of the study week. The lungs were lavaged 24 h after the single dose or after the last repeated dosing. In both size ranges, repeated dosing of particles increased the total cell number in bronchoalveolar lavage fluid (BALF) more than the respective single dose, whereas cytokine concentrations were lower after repeated dosing. The lactate dehydrogenase (LDH) responses increased up to 2-fold after repeated dosing of PM(2.5-0.2) samples and up to 6-fold after repeated dosing of PM(10-2.5) samples. PM(10-2.5) samples evoked a more extensive interstitial inflammation in the mouse lungs. The constituents with major contributions to the inflammatory responses were oxidized organic compounds and transition metals in PM(2.5-0.2) samples, Cu and soil minerals in PM(10-2.5) samples, and Zn in both size ranges. In contrast, poor biomass and coal combustion were associated with elevated levels of polycyclic aromatic hydrocarbons (PAHs) and a consistent inhibitory effect on the inflammatory activity of PM(2.5-0.2) samples. In conclusion, repeated intratracheal instillation of both fine and coarse particulate samples evoked enhanced pulmonary inflammation and cytotoxicity compared to single-dose administration. The sources and constituents of urban air particles responsible for these effects appear to be similar to those encountered in the authors' previous single-dose study.

Dose and time dependency of inflammatory responses in the mouse lung to urban air coarse, fine, and ultrafine particles from six European cities.

We investigated the dose and time dependency of inflammatory and cytotoxic responses to size-segregated urban air particulate samples in the mouse lung. Coarse (PM10-2.5), fine (PM2.5-0.2), and ultrafine (PM0.2) particles were collected in six European cities (Duisburg, Prague, Amsterdam, Helsinki, Barcelona, Athens) in selected seasons using a modified Harvard high-volume cascade impactor. Healthy C57Bl/6J mice were intratracheally exposed to the particulate samples in a 24-h dose-response study (1, 3, and 10 mg/kg) and in 4-, 12-, and 24-h time course studies (10 mg/kg). After the exposures, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: total cell number, cell differential, total protein, and lactate dehydrogenase (LDH) and cytokine (tumor necrosis alpha [TNF-alpha], interleukin-6 [IL-6], and keratinocyte-derived chemokine [KC]) concentrations. In general, PM10-2.5 samples had higher inflammatory activity than PM2.5-0.2 samples. PM0.2 samples showed negligible inflammatory activity. PM10-2.5 and PM2.5-0.2 samples caused large increases in BALF cytokine concentrations at 4 h, but not at 12 or 24 h, after exposure. The BALF total cell number and total protein concentrations increased significantly at 12 h for both the PM10-2.5 and PM2.5-0.2 samples, but only PM10-2.5 samples produced consistent, significant increases at 24 h after exposure. There was more heterogeneity in BALF cytokine and neutrophil cell number responses to PM2.5-0.2 samples than to PM10-2.5 samples between the sampling campaigns. Thus, particle size, sources, and atmospheric transformation processes affect the inflammatory activity and response duration of urban air particulate matter in the mouse lung.

Performance of a high-volume cascade impactor in six European urban environments: mass measurement and chemical characterization of size-segregated particulate samples.

The performance of a modified Harvard high-volume cascade impactor (HVCI) was evaluated in six field campaigns with size-segregated particulate samplings for chemical and toxicological characterization. The 7-week sampling campaigns in 2002-2003 in Duisburg (autumn), Prague (winter), Amsterdam (winter), Helsinki (spring), Barcelona (spring), and Athens (summer) were selected to represent contrasting urban environments and seasons of public health interest due to high particulate concentrations or previous findings in epidemiological studies. Particulate samples were collected in parallel with the HVCI (PM(10-2.5), PM(2.5-1), PM(1-0.2), PM(0.2)), a virtual impactor (VI; PM(10-2.5), PM(2.5)), and a Berner low-pressure impactor (BLPI; 10 stages between 0.035 and 10 mum in particle diameter) using a 3- or 4-day sampling duration. The campaigns exhibited different profiles with regard to particulate mass concentration, size distribution, chemical composition and meteorological conditions, thus providing a demanding setup for an overall field comparison of the HVCI with the VI and BLPI reference samplers. Size-segregated particulate mass concentration could be reasonably well measured with the present HVCI configuration. The coarse (PM(10-2.5)) and fine (PM(2.5)) particulate mass agreed within 10% with the low-volume reference samplers, and the four-stage size distribution of the HVCI followed the modal pattern of urban aerosol. The concentrations of chemical constituents measured and integrated especially for the HVCI-PM(2.5) differed to some extent from those measured from the corresponding VI-PM(2.5) samples. This implies that when investigating the association of toxicological responses with the chemical constituents of particulate matter, it is necessary to use the chemical composition data of the same samples as used in toxicological experiments.

A Chemical and Toxicological Comparison of Urban Air PM10 Collected During Winter and Spring in Finland.

We have used a new high-volume, low-cutoff inertial impactor (HVLI) in a pilot study on chemical characterization and toxicity testing of ambient air PM10 in Helsinki, Finland. Ambient air PM10 was collected at 1100 L/min in 2- to 4-day periods. Two different PM10 samples were selected to represent wintertime combustion type and springtime resuspension type particulate matter (PM) pollution. The most abundant water-soluble ions and elements were analyzed by ion chromatography and inductively coupled plasma mass spectrometry, respectively. The proinflammatory activation ¡NO and interleukin 6 (IL-6) production] and viability of cultured murine RAW 264.7 macrophages were tested in 24-h incubations with increasing mass doses (30-2000 µg per 10(6) cells) from the collected PM10 samples. The winter sample had a higher assessed PM2.5 fraction and sulfate content, and lower chloride, sodium, calcium, aluminum, copper, manganese, and especially iron contents than the spring sample. Both PMjo samples induced dose-dependent NO production in murine macrophages, and the springtime PM10 produced also a strong, dose-dependent IL-6 production. In conclusion, the HVLI proved to be a suitable technique for short-term collection of relatively large ambient air PM masses, enabling extensive chemical characterization and toxicity testing from the same samples.

Biomass burning contributions to urban aerosols in a coastal Mediterranean city.

Mean annual biomass burning contributions to the bulk particulate matter (PM(X)) load were quantified in a southern-European urban environment (Barcelona, Spain) with special attention to typical Mediterranean winter and summer conditions. In spite of the complexity of the local air pollution cocktail and the expected low contribution of biomass burning emissions to PM levels in Southern Europe, the impact of these emissions was detected at an urban background site by means of tracers such as levoglucosan, K(+) and organic carbon (OC). The significant correlation between levoglucosan and OC (r(2)=0.77) and K(+) (r(2)=0.65), as well as a marked day/night variability of the levoglucosan levels and levoglucosan/OC ratios was indicative of the contribution from regional scale biomass burning emissions during night-time transported by land breezes. In addition, on specific days (21-22 March), the contribution from long-range transported biomass burning aerosols was detected. Quantification of the contribution of biomass burning aerosols to PM levels on an annual basis was possible by means of the Multilinear Engine (ME). Biomass burning emissions accounted for 3% of PM(10) and PM(2.5) (annual mean), while this percentage increased up to 5% of PM(1). During the winter period, regional-scale biomass burning emissions (agricultural waste burning) were estimated to contribute with 7±4% of PM(2.5) aerosols during night-time (period when emissions were clearly detected). Long-range transported biomass burning aerosols (possibly from forest fires and/or agricultural waste burning) accounted for 5±2% of PM(2.5) during specific episodes. Annually, biomass burning emissions accounted for 19%-21% of OC levels in PM(10), PM(2.5) and PM(1). The contribution of this source to K(+) ranged between 48% for PM(10) and 97% for PM(1) (annual mean). Results for K(+) from biomass burning evidenced that this tracer is mostly emitted in the fine fraction, and thus coarse K(+) could not be taken as an appropriate tracer of biomass burning.