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The physical and chemical analysis of aerosols using reliable and physically traceable methods is important for the thorough investigation of airborne particles to support a better understanding of their origin as well as their health and climate impacts. Within the European Metrology Research AeroMet project, the aim of Physikalisch-Technische Bundesanstalt's (PTB) X-ray spectrometry group is to develop and establish traceable and reliable X-ray methods to measure the elemental mass deposition per unit area, the elemental composition, and the chemical binding state of particulate matter supported by a flat substrate. This approach can substantially contribute to support quantitative analytical methods during on-site measurement campaigns where portable instrumentation is employed by qualifying suitable calibration samples for commercial analytical X-ray instruments and by investigating samples collected during the field campaign., The legal definition and enforcement of air quality regulations require an accurate and reliable monitoring of airborne particulate matter (PM). The monitoring needs to be evaluated at different levels to [...]

Background: Electronic cigarettes (e-cigarettes) have become popular, in part because they are perceived as a safer alternative to tobacco cigarettes. An increasing number of studies, however, have found toxic metals/metalloids in e-cigarette emissions. Objective: We summarized the evidence on metal/metalloid levels in e-cigarette liquid (e-liquid), aerosols, and biosamples of e-cigarette users across e-cigarette device systems to evaluate metal/metalloid exposure levels for e-cigarette users and the potential implications on health outcomes. Methods: We searched PubMed/TOXLINE, Embase[R], and Web of Science for studies on metals/metalloids in e-liquid, e-cigarette aerosols, and biosamples of e-cigarette users. For metal/metalloid levels in e-liquid and aerosol samples, we collected the mean and standard deviation (SD) if these values were reported, derived mean and SD by using automated software to infer them if data were reported in a figure, or calculated the overall mean (mean [+ or -] SD) if data were reported only for separate groups. Metal/metalloid levels in e-liquids and aerosols were converted and reported in micrograms per kilogram and nanograms per puff, respectively, for easy comparison. Results: We identified 24 studies on metals/metalloids in e-liquid, e-cigarette aerosols, and human biosamples of e-cigarette users. Metal/metalloid levels, including aluminum, antimony, arsenic, cadmium, cobalt, chromium, copper, iron, lead, manganese, nickel, selenium, tin, and zinc, were present in e-cigarette samples in the studies reviewed. Twelve studies reported metal/metalloid levels in e-liquids (bottles, cartridges, open wick, and tank), 12 studies reported metal/metalloid levels in e-cigarette aerosols (from cig-a-like and tank devices), and 4 studies reported metal/metalloid levels in human biosamples (urine, saliva, serum, and blood) of e-cigarette users. Metal/metalloid levels showed substantial heterogeneity depending on sample type, source of e-liquid, and device type. Metal/metalloid levels in e-liquid from cartridges or tank/open wicks were higher than those from bottles, possibly due to coil contact. Most metal/metalloid levels found in biosamples of e-cigarette users were similar or higher than levels found in biosamples of conventional cigarette users, and even higher than those found in biosamples of cigar users. Conclusion: E-cigarettes are a potential source of exposure to metals/metalloids. Differences in collection methods and puffing regimes likely contribute to the variability in metal/metalloid levels across studies, making comparison across studies difficult. Standardized protocols for the quantification of metal/metalloid levels from e-cigarette samples are needed. https://doi.org/10.1289/EHP5686, Introduction Electronic cigarettes (e-cigarettes) are battery-operated devices that generate aerosols by heating a liquid solution (e-liquid with or without nicotine) with a metal coil (Bansal and Kim 2016; Mishra et [...]

Legionnaires' disease (LD) is an acute pneumonia caused by inhalation or aspiration of aerosols contaminated with Legionella bacteria. Legionella spp. are ubiquitous in freshwater aquatic habitats. Multiplication of Legionella in [...]

The main sources of air pollution by inorganic metal compounds, the sampling of aerosol particles, and sample preparation for analysis are considered. The nondestructive and destructive methods of analysis are compared, and their advantages and disadvantages are specified. The development of synthetic reference samples, which are used to determine a calibration function and to verify the accuracy of analytical results for both of the methods, is considered. Keywords: aerosols, inorganic pollutants, analytical techniques, sample preparation, calibration samples, accuracy DOI: 10.1134/S1061934811030087, Atmospheric pollution monitoring and workplace air pollution as the primary source of pollutants receive primary attention in environmental monitoring. Thus, Viana et al. [1] proposed to develop a model for [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.05.034 Byline: M.G. Tomasko, L.R. Doose, L.E. Dafoe, C. See Keywords: Titan Abstract: The Descent Imager/Spectral Radiometer (DISR) instrument on the Huygens probe into the atmosphere of Titan yielded information on the size, shape, optical properties, and vertical distribution of haze aerosols in the atmosphere of Titan [Tomasko, M.G., Doose, L., Engel, S., Dafoe, L.E., West, R., Lemmon, M., Karkoschka, E., 2008. Planet. Space Sci. 56, 669-707] from photometric and spectroscopic measurements of sunlight in Titan's atmosphere. This instrument also made measurements of the degree of linear polarization of sunlight in two spectral bands centered at 491 and 934nm. Here we present the calibration and reduction of the polarization measurements and compare the polarization observations to models using fractal aggregate particles which have different sizes for the small dimension (monomer size) of which the aggregates are composed. We find that the Titan aerosols produce very large polarizations perpendicular to the scattering plane for scattering near 90[degrees] scattering angle. The size of the monomers is tightly constrained by the measurements to a radius of 0.04[+ or -]0.01[mu]m at altitudes from 150km to the surface. The decrease in polarization with decreasing altitude observed in red and blue light is as expected by increasing dilution due to multiple scattering at decreasing altitudes. There is no indication of particles that produce small amounts of linear polarization at low altitudes. Author Affiliation: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USA Article History: Received 3 September 2008; Revised 1 May 2009; Accepted 5 May 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.12.012 Byline: Mathieu Vincendon (a), Y. Langevin (a), F. Poulet (a), A. Pommerol (b), M. Wolff (c), J.-P. Bibring (a), B. Gondet (a), D. Jouglet (a) Keywords: Mars; atmosphere; Mars; surface; Mars; climate; Radiative transfer; Infrared observations Abstract: The time variations of spectral properties of dark martian surface features are investigated using the OMEGA near-IR dataset. The analyzed period covers two Mars years, spanning from early 2004 to early 2008 (includes the 2007 global dust event). Radiative transfer modeling indicates that the apparent albedo variations of low to mid-latitude dark regions are consistent with those produced by the varying optical depth of atmospheric dust as measured simultaneously from the ground by the Mars Exploration Rovers. We observe only a few significant albedo changes that can be attributed to surface phenomena. They are small-scaled and located at the boundaries between bright and dark regions. We then investigate the variations of the mean particle size of aerosols using the evolution of the observed dark region spectra between 1 and 2.5 [mu]m. Overall, we find that the observed changes in the spectral slope are consistent with a mean particle size of aerosols varying with time between 1 and 2 [mu]m. Observations with different solar zenith angles make it possible to characterize the aerosol layer at different altitudes, revealing a decrease of the particle size of aerosols as altitude increases. Author Affiliation: (a) Institut d'Astrophysique Spatiale, CNRS/Universite Paris Sud, BAcentstiment 121, 91405 Orsay, France (b) Laboratoire de Planetologie de Grenoble, UJF/CNRS, BAcentst. D de Physique, B.P. 53, 38041 Grenoble Cedex 9, France (c) Space Science Institute, 18970 Cavendish Road, Brookfield, WI 53045, USA Article History: Received 18 June 2008; Revised 5 December 2008; Accepted 11 December 2008

We developed an algorithm to estimate the vertical profiles of extinction coefficients at 532 nm for three aerosol types that are water-soluble, soot, and dust particles, using the extinction and backscattering coefficients at 532 nm for total aerosols derived from high-spectral-resolution lidar (HSRL) measurements and the receiving signal at 1064 nm and total depolarization ratio at 532 nm measured with Mie scattering lidar (MSL). The mode radii, standard deviations, and refractive indexes for each aerosol component are prescribed by the optical properties of aerosols and clouds database; the optical properties for each aerosol component are computed from Mie theory on the assumption that their particles are spherical and homogeneous, except for dust. To consider the effect of nonsphericity, the dust lidar ratio at 532 nm is assumed to be 50 sr, the value that is reported for Asian dust from the other observational studies. We performed sensitivity study on retrieval errors. The errors in extinction coefficient for each aerosol component were smaller than 30% and 60% when the measurement errors were [+ or -] 5% and [+ or -] 10%. We demonstrated the ability of the algorithm by applying to the HSRL + MSL data measured at Tsukuba, Japan. Plumes consisting of water-soluble aerosols, soot, dust, or their mixture were retrieved; these results were consistent with simulation with a global aerosol transport model. Introducing the dust lidar ratio significantly improved a correlation between the retrieved dust concentration and the aerosol depolarization ratio at 532 nm derived from HSRL + MSL than the use of spherical dust optical model in the retrieval. Index Terms--Aerosols, algorithms, geophysics, laser radar.

The NASA Glory mission is intended to facilitate and improve upon long-term monitoring of two key forcings influencing global climate. One of the mission's principal objectives is to determine the global distribution of detailed aerosol and cloud properties with unprecedented accuracy, thereby facilitating the quantification of the aerosol direct and indirect radiative forcings. The other is to continue the 28-yr record of satellite-based measurements of total solar irradiance from which the effect of solar variability on the Earth's climate is quantified. These objectives will be met by flying two state-of-the-art science instruments on an Earth-orbiting platform. Based on a proven technique demonstrated with an aircraft-based prototype, the Aerosol Polarimetry Sensor (APS) will collect accurate multiangle photopolarimetric measurements of the Earth along the satellite ground track within a wide spectral range extending from the visible to the shortwave infrared. The Total Irradiance Monitor (TIM) is an improved version of an instrument currently flying on the Solar Radiation and Climate Experiment (SORCE) and will provide accurate and precise measurements of spectrally integrated sunlight illuminating the Earth. Because Glory is expected to fly as part of the A-Train constellation of Earth-orbiting spacecraft, the APS data will also be used to improve retrievals of aerosol climate forcing parameters and global aerosol assessments with other A-Train instruments. In this paper, we detail the scientific rationale and objectives of the Glory mission, explain how these scientific objectives dictate the specific measurement strategy, describe how the measurement strategy will be implemented by the APS and TIM, and briefly outline the overall structure of the mission. It is expected that the Glory results will be used extensively by members of the climate, solar, atmospheric, oceanic, and environmental research communities as well as in education and outreach activities.

Numerous studies have indicated the potential for giant and ultragiant aerosol particles to expedite the warm-rain process as a result of their extreme sizes. The central question regarding their importance is, Are they present in large enough numbers to influence the microphysics of the clouds significantly? Thus, quantification of these particles and their variability is paramount. New observations collected during the second Alliance Icing Research Study (AIRS II) are presented as evidence of the presence and variability of giant and ultragiant aerosol particles over a continental region--in this case, within the eastern Great Lakes region and parts of the midwestern United States and Canada during one month in winter 2003. Sources and factors contributing to the amount of these particles observed in the lower atmosphere were difficult to identify separately; future studies incorporating high-resolution weather modeling are likely needed.

To model aerosol--cloud interactions in general circulation models (GCMs), a prognostic cloud scheme of cloud liquid water and amount is expanded to include droplet number concentration ([N.sub.d]) in a way that allows them to be calculated using the same large-scale and convective updraft velocity field. In the scheme, the evolution of droplets fully interacts with the model meteorology. An explicit treatment of cloud condensation nuclei (CCN) activation enables the scheme to take into account the contributions to [N.sub.e] of multiple aerosol species (i.e., sulfate, organic, and sea-salt aerosols) and to consider kinetic limitations of the activation process. An implementation of the prognostic scheme in the Geophysical Fluid Dynamics Laboratory (GFDL) AM2 GCM yields a vertical distribution of [N.sub.d] with a characteristic maximum in the lower troposphere; this feature differs from the profile that would be obtained if [N.sub.d] is diagnosed from the sulfate mass concentration based on an often-used empirical relationship. Prognosticated [N.sub.d] exhibits large variations with respect to the sulfate mass concentration. The mean values are generally consistent with the empirical relationship over ocean, but show negative biases over the Northern Hemisphere midlatitude land, perhaps owing to the neglect of subgrid variations of large-scale ascents and inadequate convective sources. The prognostic scheme leads to a substantial improvement in the agreement of model-predicted present-day liquid water path (LWP) and cloud forcing with satellite measurements compared to using the empirical relationship. The simulations with preindustrial and present-day aerosols show that the combined first and second indirect effects of anthropogenic sulfate and organic aerosols give rise to a steady-state global annual mean flux change of -1.8 W [m.sup.-2], consisting of -2.0 W[m.sup.-2] in shortwave and 0.2 W [m.sup.-2] in longwave. The ratios of the flux changes in the Northern Hemisphere (NH) to that in Southern Hemisphere (SH) and of the flux changes over ocean to that over land are 2.9 and 0.73, respectively. These estimates are consistent with the averages of values from previous studies stated in a recent review. The model response to higher [N.sub.d] alters the cloud field; LWP and total cloud amount increase by 19% and 0.6%, respectively. Largely owing to high sulfate concentrations from fossil fuel burning, the NH midlatitude land and oceans experience strong radiative cooling. So does the tropical land, which is dominated by biomass burning-derived organic aerosol. The computed annual, zonal-mean flux changes are determined to be statistically significant, exceeding the model's natural variations in the NH low and midlatitudes and in the SH low latitudes. This study reaffirms the major role of sulfate in providing CCN for cloud formation.

We apply principal component analysis (PCA) to estimate how much information about atmospheric aerosols could be retrieved from solar-reflected radiances observed over oceans by a satellite sensor as a function of the number of wavelength bands, viewing angles, and Stokes parameters. It is assumed that our virtual satellite sensor can simultaneously perform multispectral, multiangle, and linear polarization measurements of the radiances, and the following quantities are used to vary: aerosol optical thickness, single-scattering albedo (SSA) of aerosol particles, height of the aerosol layer, aerosol model (includes size distribution parameters and optical properties), and wind speed. The real refractive index was kept constant and, therefore, is not part of the analysis. To calculate the number of significant principal components (SPCs), the cumulative percent variance rule is used, which takes into account anticipated errors of measurements. The reported results predict how much additional information can be retrieved from observations by adding more wavelength, angle, and polarization channels. For example, for the Moderate Resolution Imaging Spectroradiometer instruments ([lambda] > 0.5 [micro]m), the number of SPCs is two to three; for Multiangle Imaging SpectroRadiometer, three to five; for Polarization and Directionality of the Earth Reflectances, five to ten; while for the future Glory/Aerosol Polarization Sensor instrument, it is 6-11 (when using eight out of its > 100 view angles). The ranges reflect view conditions and analysis method. Our calculations show that the observations should be most sensitive to the aerosol model followed in decreasing order by optical thickness, SSA, and aerosol height. We found that there is no systematic increase in the information about aerosol starting from 10-15 view angles for unpolarized observations and 30 view angles for those with linear polarization. It is achievable with modern detectors to retrieve up to 10 and 16 SPCs from unpolarized and polarized observations, respectively. The methodology and results of our PCA can be useful for estimating the reliability of aerosol parameters retrieved from existing and future satellite observations. Index Terms--Aerosols, remote sensing, satellite applications.

Two aerosol extinction models have been developed using statistical analysis of long-term optical transmission measurements in Sweden performed at two locations from July 1977 to June 1982. The aerosol volume extinction coefficient for infrared (IR) radiation is calculated by the models with visibility, temperature, and air pressure as input parameters. As in the MODTRAN model, the IR extinction coefficient is proportional to the coefficient at 550 rim, which depends on the visibility. In the new models, the wavelength dependence of the extinction also depends on the visibility. The models predict significantly higher attenuation in the IR than does the Rural aerosol model from MODTRAN, which is commonly used. Comparison with the Maritime model shows that the new models predict lower extinction values in the 3-5 [micro]m region and higher values in the 8-12 [micro]m region. The uncertainties in terms of variance levels are calculated by the models. The properties of aerosols, and thereby the extinction coefficient, are partly correlated to local meteorological parameters, which enables the calculation of a mean predicted value. A substantial part of the variation is, however, caused by conditions in the source area and along the trajectory path of the aerosols. They are not correlated to the local meteorological parameters and therefore cause the variance in the models. OCIS codes: 010.0010, 010.1110, 010.1310, 010.1320, 290.2200.

Analyses of trends of the orographic winter precipitation enhancement factor Ro along the coastal mountain ranges of the west coast of the United States show a pattern of decreasing Ro during the last century by as much as -24% from the southern border to central California, to no decrease in northern California and Oregon, and to a renewed decrease of Ro (-14%) in Washington to the Seattle area east of the Puget Sound. Similar decreases also occurred well inland, over Arizona, New Mexico, Utah (this study), and the east slopes of the Colorado Rockies (already documented prior to this study). Both absolute precipitation amounts and Ro are affected by fluctuations in the atmospheric circulation patterns, such as those associated with the Pacific decadal oscillation and the Southern Oscillation index. However, these climatic fluctuations cannot explain the observed trends in Ro. Although the trends of aerosols are available only since 1988, aerosol measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) aerosol monitoring network show that negative trends in Ro are associated with elevated concentrations of fine aerosols [particulate matter less than 2.5 [micro]m in diameter (PM 2.5)]. The PM 2.5 showed stability or some increase in the areas where their levels were elevated and decreasing trends of Ro were noted. Strong decreasing trends of the coarse aerosols (PM 10-PM 2.5) were noted, especially in the areas with elevated levels of PM 2.5. The decreasing trend in coarse aerosols (the coarse aerosols may act to initiate and enhance precipitation), in conjunction with the constancy and/or increases of the small aerosols (small aerosols suppress precipitation), can explain the continuing decreases in orographic precipitation during the last two decades despite the indicated improvement in the conventional air quality standards.

We present a robust and computationally efficient method for retrieving aerosol optical depth (AOD) from top-of-atmosphere ATSR-2 (Along-Track Scanning Radiometer) and AATSR (Advanced ATSR) reflectance data that is formulated to allow retrieval of the AOD from the 11 year archive of (A)ATSR data on the global scale. The approach uses a physical model of light scattering that requires no a priori information on the land surface. Computational efficiency is achieved by using precalculated lookup tables (LUTs) for the numerical inversion of a radiative-transfer model of the atmosphere. Estimates of AOD retrieved by the LUT approach are tested on AATSR data for a range of global land surfaces and are shown to be highly correlated with sunphotometer measurements of the AOD at 550 nm. (Pearson's correlation coefficient [r.sup.2] is 0.71.) OCIS codes: 280.1100, 280.1310, 290.1090.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solener.2005.03.008 Byline: F.R. Martins, E.B. Pereira Keywords: Solar radiation; Radiative transfer model; Biomass burning aerosols Abstract: A new aerosol parameterization was developed and implemented for operational use with the BRASIL-SR model. The goal is to improve the assessment of solar energy resources in Brazil. Optical properties of the aerosols from burning biomass were obtained using software package OPAC and are in good agreement with previous field measurements made in Brazil. Three different mixture ratios of black carbon were used to cover the full range of typical measured values. The atmospheric transport model SMOKE provided the aerosol profile. An evaluating period of 11days in August/1995 and ground measurements from six sites situated in Amazon region was used to validate the results. The global solar irradiation estimates obtained with new aerosol parameterization, presented smaller mean bias error in all ground sites. The correlation among estimates and measured values for surface global solar irradiation improved about 2.5 times by adopting an aerosol composition with 5% of black carbon. Author Affiliation: Centre for Weather Forecast and Climate Studies -- Brazilian, Institute of Space Research (CPTEC-INPE), P.O. Box 515, Sao Jose dos Campos, SP 12201-970, Brazil Article History: Received 2 March 2004; Revised 8 March 2005; Accepted 9 March 2005 Article Note: (miscellaneous) Communicated by: Associate Editor Pierre Ineicien

Airborne in situ measurements of vertical profiles and horizontal transects of aerosol optical and physical properties, obtained during the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaign off the East Coast of the United States during the summer of 2001, are presented. Most of the measurements were obtained in relatively clean air dominated by airflows that had passed over Canada and the northern Atlantic Ocean. Results from the 17 July and 2 August 2001 flights are presented; on these days, the aerosol loading was relatively high. In the lower troposphere, [[omega].sub.0] values at a wavelength of 550 nm were consistently above 0.93 throughout the field experiment, indicating the dominance of weakly absorbing aerosol. Particle number size distributions are presented and discussed for transects at altitudes ~0.05-3.5 km above mean sea level. Particles with diameters ([D.sub.p])