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PubMed1988

Genotoxicity of organic extracts from atmospheric particles.

Experiments to evaluate the genotoxic potentialities of urban air particles sampled in Paris (France) after organic solvent extraction have been carried out using four in vitro genotoxicity tests. The two bacterial tests (the Ames test and the SOS Chromotest) demonstrate the genotoxicity of the organic extracts of atmospheric particles; two additional tests (induction of 6-thioguanine mutants and sister chromatid exchanges), carried out on V79 Chinese hamster cells, also confirm these potentialities. These results show clearly that particulate organic extracts induce point mutations in both bacteria and mammalian cells, or the cellular response (SOS repair) to these mutations in bacteria; likewise, they are responsible for clastogenic effects in mammalian cells. Genotoxicity is due either to direct genotoxic chemicals or to active metabolic products of the action of microsomal enzymes. The optimalization of testing procedures is discussed in order to appreciate the contribution of genotoxicity tests to the study of atmospheric pollution.

Air Pollution↗
PubMed2003

[Organic and elemental carbon in atmospheric particles].

The carbonaceous material, present especially in the respirable atmospheric particulate, is emitted directly from the combustion processes and it is composed of an organic fraction, organic carbon (OC) and of a fraction which is resistant to oxidation at temperatures below approximately 400 degrees C, elemental carbon (EC). In this paper OC and EC concentrations are reported measured in downtown Rome and in a park, Villa Ada, by means of an analyzer which utilizes the thermal properties of the particles. The temporal trends of EC and OC in Rome are in good agreement during the entire period investigated (correlation coefficient between 0.86-0.90). On the other hand the comparison with Villa Ada shows a different contribution from secondary origin pollutants. The carbonaceous fraction in the total particulate mass, measured by means of a TEOM analyzer, varies between 30-40% in downtown and 20-25% in the park, respectively.

Air Pollution↗
PubMed2005

Quantitative determination of low-Z elements in single atmospheric particles on boron substrates by automated scanning electron microscopy-energy-dispersive X-ray spectrometry.

Atmospheric aerosols consist of a complex heterogeneous mixture of particles. Single-particle analysis techniques are known to provide unique information on the size-resolved chemical composition of aerosols. A scanning electron microscope (SEM) combined with a thin-window energy-dispersive X-ray (EDX) detector enables the morphological and elemental analysis of single particles down to 0.1 microm with a detection limit of 1-10 wt %, low-Z elements included. To obtain data statistically representative of the air masses sampled, a computer-controlled procedure can be implemented in order to run hundreds of single-particle analyses (typically 1000-2000) automatically in a relatively short period of time (generally 4-8 h, depending on the setup and on the particle loading). However, automated particle analysis by SEM-EDX raises two practical challenges: the accuracy of the particle recognition and the reliability of the quantitative analysis, especially for micrometer-sized particles with low atomic number contents. Since low-Z analysis is hampered by the use of traditional polycarbonate membranes, an alternate choice of substrate is a prerequisite. In this work, boron is being studied as a promising material for particle microanalysis. As EDX is generally said to probe a volume of approximately 1 microm3, geometry effects arise from the finite size of microparticles. These particle geometry effects must be corrected by means of a robust concentration calculation procedure. Conventional quantitative methods developed for bulk samples generate elemental concentrations considerably in error when applied to microparticles. A new methodology for particle microanalysis, combining the use of boron as the substrate material and a reverse Monte Carlo quantitative program, was tested on standard particles ranging from 0.25 to 10 microm. We demonstrate that the quantitative determination of low-Z elements in microparticles is achievable and that highly accurate results can be obtained using the automatic data processing described here compared to conventional methods.

Journal Article↗
PubMed2001

Detection of alkaline ultrafine atmospheric particles at Bakersfield, California.

Two collected micro-orifice uniform deposit impactors (MOUDIs) and a filter-based sampler were used to measure the size distribution and chemical composition of atmospheric particulate matter at Bakersfield, CA, between January 14 and 23, 1999. The peak number concentration of airborne ultrafine particles measured was 1.45 x 10(11) m-3, which is a factor of approximately 3 higher than the peak airborne ultrafine-particle number concentration measured previously in Pasadena, CA. Chemical analysis revealed that airborne ultrafine particles (Dp < 0.1 micron) at Bakersfield contained significant amounts of water-soluble species, including calcium, sodium, ammonium ion, nitrate, and sulfate. Other chemical species detected in the ultrafine size range included potassium, iron, copper, zinc, and strontium. A balance of aqueous ions showed that ultrafine particles were alkaline in nature with calcium acting as the dominant cation. Bulk samples of airborne particles with diameter less than 2.0 microns (PM2.0) were essentially neutral, but particle acidity was found to be a strong function of particle size. The results of this experiment suggest that areas deep in the human lung that preferentially collect particles in the ultrafine size range could be exposed to locally acidic or alkaline conditions even if the integrated airborne particle complex is essentially neutral.

Air Pollutants↗
PubMed2006

Trace metal concentrations and water solubility in size-fractionated atmospheric particles and influence of road traffic.

The abundance and the behavior of metals (Al, Ti, Mn, Fe, Co, Ni, Cu, Zn, Se, Ag, Cd, Sn, Ba, Pt, Hg, and Pb) and ions (Na+ K+ Mg2+ Ca2+, NH4+, Cl-, NO3-, SO4(2-), PO4(3-), and oxalate) in size-fractionated atmospheric particulate matter (PM) were studied in the U. K. and Ireland at four observation sites simulating extreme degrees of vehicular-traffic influence in the environment. Trace metals in urban PM showed distinct types of size-fractionated behavior depending on the particle sources from which they originate. In coarse PM (1.5 < Dp < 3.0 microm) the concentrations of copper, barium, and iron correlated closely across over 2 orders of magnitude in urban air, which is seen as evidence that major portions of transition metals (Cu, Ba, Fe, and Mn) are released through abrasive vehicular emissions, particularly the wear of brake linings. Further results are strongly indicative of a decoupling of coarse iron and calcium, the former arising predominantly from vehicles, the latter from soil resuspension. In fine PM (Dp < 0.5 microm), several combustion and secondary sources of particulates were identified, but these were much less unique in terms of elemental fingerprints. An analysis of the water solubility of trace metals yielded that solubility varies considerably with element and, to a lesser extent, with particle size. Notable differences were found to the elemental water solubilities determined in previous work, partially explained by differences in extraction procedures.

Air Pollutants↗
PubMed2005

Water uptake on mineral dust and soot: a fundamental view of the hydrophilicity of atmospheric particles?

The interaction of water vapour with mineral dust and soot surfaces has been studied in the temperature range 203 K < T < 298 K using a Knudsen cell reactor. For the uptake of water on mineral dust an initial uptake coefficient of gamma(ini) = (6.3 +/- 0.7) x 10(-2) independent of temperature has been determined. In contrast the desorption rate has been found to be strongly temperature dependent with desorption rate constants decreasing from 1 x 10(-3) at 265 K to 1 x 10(-4) at 223 K. In addition, relatively high surface coverages have been determined from which an adsorption enthalpy of -40 kJ mol(-1) is inferred. For the uptake of water on soot the initial uptake coefficient has been found to be independent of temperature with a value of gamma(ini) = (4.7 +/- 0.2) x 10(-2), similar to the case of mineral dust. However, the corresponding desorption rate constants have been found to be three orders of magnitude larger than for mineral dust. Consistent with this finding, low surface coverages with an adsorption enthalpy of -27 kJ mol(-1) have been derived. A comparison of the uptake kinetics and adsorption enthalpies of water on mineral dust and soot leads to the conclusion that water is much stronger interacting with mineral dust than with soot. In terms of a hydrophilicity concept the results suggest, that mineral dust may be regarded as hydrophilic whereas soot is hydrophobic and that fundamental kinetic and thermochemical quantities may be related to that concept.

Adsorption↗
PubMedDate not supplied

Characterization of atmospheric particles by electron probe X-ray microanalysis.

Microchemical glass standards were used to validate a quantitation method based on peak-to-background (P/B) ratios from electron probe x-ray microanalysis spectra. This standardless method was applied to the determination of concentrations of individual particles from Malpha or Lalpha lines, as well as from Kalpha lines. The algorithm was tested on particulate glass samples for diameters ranging from 1 to 20 microm. The determined concentrations did not depend on particle size. The certified values for elements were well matched, except for Na, which may migrate under electron bombardment. Finally, classification of qualitative results obtained for aerosol particles was completed by the P/B quantitative method.

Journal Article↗
PubMed2004

Seasonal variability of 1-chloropyrene on atmospheric particles and photostability in toluene.

The occurrence of a mutagenic compound, 1-chloropyrene (Cl-Py), in extracts of ambient particulate matter at an urban site in Japan has been investigated. Samples were collected with a high-volume air sampler for 24 h periods over the course of 1 week in winter (February), spring (May), summer (August), and autumn (November) 2002. The Cl-Py levels showed seasonal variation, ranging from 2.4 pg/m(3) (summer) to 18.9 pg/m(3) (winter). This variation would indicate that the lower temperatures in winter results in an increased distribution of Cl-Py from vapor phase to the particle phase. In addition, there is also the possibility that ambient Cl-Py is emitted from seasonal sources or is susceptible to photodegradation by sunlight, or both. The photodegradation of Cl-Py in a laboratory experiment was conducted to simulate the compound's fate on airborne particle surfaces. The degradation of Cl-Py proceeded by a first-order reaction with a rate constant of 0.72 h(-1). In the presence of a radical sensitizer, 9,10-anthraquinone (AQ), the photodegradation rate of Cl-Py was elevated in comparison with the rate in the absence of AQ. In addition, the dechlorination of Cl-Py (i.e., the formation of Py) occurred in the presence of AQ.

Air Pollutants↗
PubMed2002

Light extinction by fine atmospheric particles in the White Mountains region of New Hampshire and its relationship to air mass transport.

Chemical, optical, and physical measurements of fine aerosols (aerodynamic diameter < or = 2.5 microm) have been performed at a mountaintop location adjacent to the White Mountain National Forest in northern NH, USA. A 1-month long sampling campaign was conducted at Cranmore Mountain during spring 2000. We report on the apportionment of light extinction by fine aerosols into its major chemical components, and relationships between variations in aerosol parameters and changes in air mass origin. Filter-based, 24-h integrated samples were collected and analyzed for major inorganic ions, as well as organic (OC), elemental (EC), and total carbon. Light scattering and light absorption coefficients were measured at 5-min intervals using an integrating nephelometer and a light absorption photometer. Fine particle number density was measured with a condensation particle counter. Air mass origins and transport patterns were investigated through the use of 3-day backward trajectories and a synoptic climate classification system. Two distinct transport regimes were observed: (1) flow from the north/northeast (N/NE) occurred during 9 out of 18 sample-days; and (2) flow from the west/southwest (W/SW) occurred 8 out of 18 sample-days. All measured and derived aerosol and meteorological parameters were separated into two categories based on these different flow scenarios. During W/SW flow, higher values of aerosol chemical concentration, absorption and scattering coefficients, number density, and haziness were observed compared to N/NE flow. The highest level of haziness was associated with the climate classification Frontal Atlantic Return, which brought polluted air into the region from the mid-Atlantic corridor. Fine particle mass scattering efficiencies of (NH4)2SO4 and OC were 5.35 +/- 0.42 m2 g(-1) and 1.56 +/- 0.40 m2 g(-1), respectively, when transport was out of the N/NE. When transport was from the W/SW the values were 4.94 +/- 0.68 m2 g(-1) for (NH4)2SO4 and 2.18 +/- 0.91 m2 g(-1) for OC. EC mass absorption efficiency when transport was from the N/NE was 9.66 +/- 1.06 m2 g(-1) and 10.80 +/- 1.76 m2 g(-1) when transport was from the W/SW. Results from this work can be used to predict visual air quality in the White Mountain National Forest based on a forecasted synoptic climate classification and its associated visibility.

Aerosols↗
PubMedDate not supplied

Biological effects of atmospheric particles on human bronchial epithelial cells. Comparison with diesel exhaust particles.

Epidemiological studies have associated the increase of respiratory disorders with high levels of ambient particulate matter (PM) levels although the underlying biological mechanisms are unclear. PM are a complex mixture of particles with different origins but in urban areas, they mainly contain soots from transport like Diesel exhaust particles (DEP). In order to determine whether PM biological effects can be explained by the presence of DEP, the effects of urban PM, DEP and carbon black particles (CB) were compared on a human bronchial epithelial cell line (16-HBE14o-). Two types of PM were used : reference material (RPM) and PM with an aerodynamic diameter < or =2.5 microm collected in Paris with a high volume sampler (VPM). From 10 to 30 microg/cm2, cell viability was never modified whatever the particles. However, DEP and to a lower extent PM inhibited cell proliferation, induced the release of a pro-inflammatory cytokine, GM-CSF, and generated a pro-oxidant state as shown by the increased intracellular peroxides production. By contrast, CB never induced such effects. Nevertheless CB are more endocytosed than DEP whereas PM are the less endocytosed particles. In conclusion, PM induced to a lower extent the same biological effects than DEP in 16-HBE cells suggesting that particle characteristics should be thoroughly considered in order to clearly correlate adverse effects of PM to their composition and to clarify the role of DEP in PM effects.

Air Pollutants↗
PubMed2005

Continuous collection of soluble atmospheric particles with a wetted hydrophilic filter.

Approximately one-third of the area (14-mm diameter of a 25-mm diameter) of a 5-microm uniform pore size polycarbonate filter is continuously wetted by a 0.25 mL/min water mist. The water forms a continuous thin film on the filter and percolates through it. The flowing water substantially reduces the effective pore size of the filter. At the operational air sampling flow rate of 1.5 standard liters per minute, such a particle collector (PC) efficiently captures particles down to very small size. As determined by fluorescein-tagged NaCl aerosol generated by a vibrating orifice aerosol generator, the capture efficiency was 97.7+% for particle aerodynamic diameters ranging from 0.28 to 3.88 microm. Further, 55.3 and 80.3% of 25- and 100-nm (NH4)2SO4 particles generated by size classification with a differential mobility analyzer were respectively collected by the device. The PC is integrally coupled with a liquid collection reservoir. The liquid effluent from the wetted filter collector, bearing the soluble components of the aerosol, can be continuously collected or periodically withdrawn. The latter strategy permits the use of a robust syringe pump for the purpose. Coupled with a PM2.5 cyclone inlet and a membrane-based parallel plate denuder at the front end and an ion chromatograph at the back end, the PC readily operated for at least 4-week periods without filter replacement or any other maintenance.

Journal Article↗