Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AEROSOLS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed1986

Phorbol myristate acetate lung injury and airway responsiveness to aerosol histamine in awake sheep.

To test the hypothesis that phorbol myristate acetate (PMA), a potent granulocyte activator, would increase airway responsiveness to aerosol histamine, we quantitated airway responsiveness to aerosol histamine in nine awake sheep before and 4 1/2 hours after intravenous PMA, 5 micrograms/kg. A dose-response curve to aerosol histamine was constructed by administering histamine aerosols of 0.1, 0.3, 1.0, 3.0, 10.0, and 30.0 mg/ml sequentially until dynamic lung compliance (Cdyn) decreased to less than or equal to 65% baseline. The dose of histamine that caused a reduction of Cdyn to 65% of baseline (ED65Cdyn) was determined by linear interpolation. We then administered PMA, defined a new baseline Cdyn 4 1/2 hours later, and administered aerosol histamine as before. Control experiments were performed on another day in eight of the nine sheep by administering aerosol histamine 4 1/2 hours apart without infusing PMA. Histamine responsiveness did not change significantly during 4 1/2 hours in the control experiments. Control (preaerosol histamine) Cdyn decreased from 0.090 +/- 0.010 L/cm H2O before PMA to 0.048 +/- 0.004 L/cm H2 4 1/2 hours after PMA. The mean pre-PMA ED65Cdyn for the nine sheep was 3.80 +/- 0.87 mg/ml, and the mean post-PMA ED65Cdyn was 2.13 +/- 0.98 mg/ml (p less than 0.05). When individual dose-response curves are examined, the small statistical increase in aerosol histamine responsiveness does not appear important, especially when the increase is compared to the changes previously reported after endotoxemia in unanesthetized sheep.

Aerosols↗
PubMed1986

Carcinogenicity of sodium dichromate and chromium (VI/III) oxide aerosols inhaled by male Wistar rats.

In inhalation chambers, male Wistar rats of the strain TNO-W74 were continuously exposed to submicron aerosols of sodium dichromate and to a pyrolyzed Cr(VI)/Cr(III) (3:2) oxide mixture. The sodium dichromate (Na2Cr2O7) aerosol had the chromium concentrations of 25, 50 and 100 micrograms/m3, the chromium oxide mixture (Cr5O12) had the chromium concentration of 100 micrograms/m3. After 18 months of inhalation the rats were held under conventional conditions for a further year. The experimental groups consisted of 20 rats and the control group of 40 rats. More than 90% of the rats in each group reached 2 years. At the end of the study the mortality rates amounted to 35%, 45% and 25% in the 3 sodium dichromate aerosol groups, respectively, and 50% in the chromium oxide mixture aerosol group, which was not significantly different from that of the controls (42.5%), living under the same conditions in filtered fresh air. In all sodium dichromate exposed groups significant effects were neither found clinically nor from hematology and clinical chemistry compared to the controls. In the chromium oxide mixture group, however, there was a number of significant findings. Elevated white and red blood cell counts and serum cholesterol as well as decreased serum total immunoglobulin levels at different stages of the study were observed together with few local lung effects determined histopathologically in this group. We assume that these effects are mainly due to the increased chromium lung burden of the rats. At the end of the study the lung chromium retention was about 10 times higher for the rats exposed to chromium oxide versus sodium dichromate at an aerosol Cr-concentration of 100 micrograms/m3, while the kidney chromium retention was measured to be nearly equal in both groups. Three primary lung tumors (2 adenomas and 1 adenocarcinoma) and 1 malign tumor of the pharynx were found at the highest Cr-concentration (100 micrograms/m3) of the sodium dichromate aerosol, 1 primary adenoma of the lung was in the chromium oxide mixture group exposed also to a Cr-concentration of 100 micrograms/m3. No primary lung tumors were observed in the other experimental and control groups. These results indicate a weak carcinogenicity at 100 micrograms/m3 for the rats continuously exposed to submicron Na2Cr2O7 and Cr5O12 aerosols. Thus, there may be a small carcinogenic risk from occupational relevant chromium air levels. However, results have to be confirmed with larger animal populations.

Administration, Inhalation↗
PubMed2005

Shortwave radiative forcing efficiency of urban aerosols--a case study using ground based measurements.

Aerosols reduce the surface reaching solar flux by scattering the incoming solar radiation out to space. Various model studies on climate change suggest that surface cooling induced by aerosol scattering is the largest source of uncertainty in predicting the future climate. In the present study measurements of aerosol optical depth (AOD) and its direct radiative forcing efficiency has been presented over a typical tropical urban environment namely Hyderabad during December, 2003. Measurements of AOD have been carried out using MICROTOPS-II sunphotometer, black carbon aerosol mass concentration using Aethalometer, total aerosol mass concentration using channel Quartz Crystal Microbalance (QCM) Impactor Particle analyser and direct normal solar irradiance using Multifilter Rotating Shadow Band Radiometer (MFRSR). Diurnal variation of AOD showed high values during afternoon hours. The fraction of BC estimated to be approximately 9% in the total aerosol mass concentration over the study area. Results of the study suggest -62.5 Wm(-2) reduction in the ground reaching shortwave flux for every 0.1 increase in aerosol optical depth. The results have been discussed in the paper.

Aerosols↗
PubMed2005

Validation of a gas chromatography/mass spectrometry method for the quantification of aerosolized Jet Propellant 8.

Jet Propellant 8 (JP-8) jet fuel is a kerosene-based fuel containing hundreds of hydrocarbons used by the military in NATO countries. Previous rodent inhalation studies carried out with aerosolized JP-8 never evaluated the exposure chamber atmosphere. For this reason, our laboratory developed an analytical method, with an accuracy of better than 80% and precision of better than 20%, for JP-8 aerosol and vapor samples using gas chromatography/mass spectrometry (GC/MS). A method was developed for quantification of selected individual components of JP-8 and for the total amount of JP-8 in aerosolized fuel. A 34 component surrogate hydrocarbon mixture (SHM) was developed and used for simultaneous analysis of the individual components. Three separate runs containing a standard curve and five replicates each at the selected concentrations were analyzed for both the SHM and neat JP-8. The resulting interday accuracy (100-percent relative error) and precision (relative standard deviation) values for the SHM were 86.5% or better and 8.0% or better, respectively. The intraday accuracy and precision values ranged from 99.29% to 84.50% and 0.97% to 12.4%, respectively. For the total amount of JP-8 in aerosol and vapor, the interday accuracy was 83.7% or better and interday precision was 7.0% or better. The intraday accuracy and precision values ranged from 94.8% to 80.4% and 2.4% to 10.5%, respectively. We then used this method to analyze samples collected from an inhalation chamber. From the data obtained, we are able to account for approximately 40-44% of the mass of the aerosol portion and 68-70% of the mass of the vapor portion. The aerosol represented 6-10% of the total mass of the aerosolized JP-8 fuel with the remaining portion being the vapor. From these experiments individual components were identified for further in vivo and in vitro toxicological testing.

Aerosols↗
PubMed2001

Study of fifteen respirable aerosol samplers used in occupational hygiene.

European and international standards lay down criteria for the size-selective aerosol sampling in occupational hygiene. Aerosol samplers are supposed to match these target sampling criteria. This study focused on 15 aerosol samplers used to sample the conventional respirable fraction. An aerodynamic particle sizer (APS) method was used to measure the sampling efficiency of the samplers in a low-velocity wind tunnel. Polydisperse coal dust was generated as the test aerosol. The data were fitted by an appropriate mathematical model. For some instruments the results show serious deviations from the conventional target curve, whereas other devices meet the convention quite well. The flow rate of certain cyclone-separator-based instruments was optimized to adjust their sampling efficiency. The mass concentration bias and accuracy of the samplers were calculated for a number of ranges of particle size distributions of aerosols commonly found in industrial workplaces. Finally, the performance of each sampler was evaluated using bias and accuracy maps. Most of these samplers are suitable for sampling the CEN-ISO-ACGIH respirable fraction of aerosols, but several require modification of the flow rate. For real industrial situations, the rough knowledge of the aerosol size distribution can guide the choice of an appropriate sampling technique.

Aerosols↗
PubMed1997

Morphine pharmacokinetics after pulmonary administration from a novel aerosol delivery system.

BACKGROUND: Successful pharmacotherapy of pain often depends on the mode of drug delivery. A novel, unit dose, aqueous aerosol delivery system (AERx Pulmonary Drug Delivery System) was used to examine the feasibility of the pulmonary route for the noninvasive systemic administration of morphine. METHODS: The study had two parts: (1) a dose-ranging study in four subjects with three consecutive aerosolized doses of 2.2, 4.4, and 8.8 mg (nominal) morphine sulfate pentahydrate at 40-minute intervals, and (2) a crossover study, on separate days, in six subjects with 4.4 mg (nominal) aerosolized morphine sulfate administered over 2.1 minutes on three occasions and intravenous infusions of 2 and 4 mg over 3 minutes. Subjects were healthy volunteers from 19 to 34 years old. Arterial blood was sampled for a total of 6 hours and plasma morphine concentrations were measured by gas chromatography-mass spectrometry. RESULTS: In part 1, plasma morphine concentrations were proportional to dose. In part 2, the mean +/- SD peak plasma concentration (Cmax) occurred at 2.7 +/- 0.8 minutes after the aerosol dose, with mean values for Cmax of 109 +/- 85, 165 +/- 22, and 273 +/- 114 ng/ml for the aerosol and 2 and 4 mg intravenous doses, respectively. The bioavailability [AUC(0-360 min)] of aerosol-delivered morphine was approximately 100% relative to intravenous infusion, with similar intersubject variability in AUC for both routes (coefficient of variation < 30%). CONCLUSION: The time courses of plasma morphine concentrations after pulmonary delivery by the AERx system and by intravenous infusions were similar. This shows the utility of the pulmonary route in providing a noninvasive method for the rapid and reproducible systemic administration of morphine if an appropriate aerosol drug delivery system is used.

Administration, Inhalation↗
PubMed2000

Pharmacological evaluation of aerosolized cannabinoids in mice.

The reemergence on the debate of the use of marijuana for medicinal purposes has been the impetus for developing an acceptable delivery form of aerosolized cannabinoids. The goals of the present study were to: (1) develop and characterize the physical properties of an aerosolized form of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the major psychoactive constituent present in marijuana; and (2) assess the pharmacological effects of cannabinoid inhalation in mice. A Small Particle Aerosol Generator (SPAG) nebulizer, used to generate the aerosol, had an output of approximately 0.154 mg/l of aerosolized Delta(9)-THC with a 2.0 microm mass median aerodynamic diameter and a 2.2 geometric standard deviation (GSD). Virtually all the particles were less than 5.0 microm in diameter suggesting that they were sufficiently small to penetrate deeply into the lungs. Inhalation exposure to aerosolized Delta(9)-THC in mice elicited antinociceptive effects that were dependent on concentration and exposure time with an estimated Delta(9)-THC dose of 1.8 mg/kg. On the other hand, inhalation exposure to Delta(9)-THC failed to produce two other indices indicative of cannabinoid activity, hypothermia and decreases in spontaneous locomotor activity. The antinociceptive effects occurred within 5 min of exposure and lasted approximately 40 min in duration. The cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl (SR 141716A), but not naloxone, blocked these antinociceptive effects (AD(50)=0.09 mg/kg) indicating a cannabinoid receptor mechanism of action. Similarly, inhalation exposure to a water soluble cannabinoid analog, 3-(5'-cyano-1', 1'dimethylheptyl)-1-(4-N-morpholinobutyrloxy)-Delta(8)-te trahydrocann abinol (O-1057), produced antinociception that was blocked by SR 141716A. These results demonstrate that the development of an aerosolized form of cannabinoids for human medicinal use is feasible.

Administration, Inhalation↗
PubMed1997

Treatment of refractory acute allograft rejection with aerosolized cyclosporine in lung transplant recipients.

Lung transplant recipients who have persistent acute cellular rejection are at increased risk for the development of chronic rejection, the leading cause of reduced long-term survival. This study evaluated the use of aerosolized cyclosporine as rescue therapy for unremitting acute rejection. Between June 1993 and March 1996, 18 patients with rejection that failed to resolve after therapy with pulse steroids and antilymphocyte globulin were enrolled in the study. Aerosolized cyclosporine A (300 mg) treatment was initiated for 10 consecutive days followed by a maintenance regimen of 3 days per week. Efficacy was assessed by graft histologic and pulmonary function testing. With the use of linear regression, results in these patients were compared with those in 23 control patients, matched for histologic acute rejection, who had continued to receive conventional rescue therapy. Two patients were unable to tolerate the treatments and were withdrawn from the study. Significant improvement in histologic rejection occurred in 14 of the remaining 16 patients after a mean of 37 days of aerosolized cyclosporine therapy. Measures of forced vital capacity and forced expiratory volume in 1 second (change in percent predicted/100 days plus or minus the standard error) increased over time in the treated patients whereas the condition of control patients declined despite repeated attempts at conventional rescue (forced vital capacity, aerosolized cyclosporine group, 4.6 +/- 2.9 vs control group -8.1 +/- 1.9, p = 0.001; forced expiratory volume in 1 second, aerosolized cyclosporine group, 2.1 +/- 4.4 vs control group -9.8 +/- 2.6, p = 0.043). Renal and hepatic toxicity during cyclosporine therapy was not observed. The incidence of acute histologic rejection (> or = A2) decreased from 2.49 +/- 0.68 episodes/100 days before aerosolized cyclosporine therapy to 0.72 +/- 0.3 episodes/100 days (p < 0.05). In summary, aerosolized cyclosporine is a safe and effective therapy for acute rejection that has failed to improve with conventional treatment.

Acute Disease↗
PubMed1998

Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies.

Assessment of strategies for engineering controls for the prevention of airborne infectious disease transmission to patients and to health care and related workers requires consideration of the factors relevant to aerosol characterization. These factors include aerosol generation, particle size and concentrations, organism viability, infectivity and virulence, airflow and climate, and environmental sampling and analysis. The major focus on attention to engineering controls comes from recent increases in tuberculosis, particularly the multidrug-resistant varieties in the general hospital population, the severely immunocompromised, and those in at-risk and confined environments such as prisons, long-term care facilities, and shelters for the homeless. Many workers are in close contact with persons who have active, undiagnosed, or insufficiently treated tuberculosis. Additionally, patients and health care workers may be exposed to a variety of pathogenic human viruses, opportunistic fungi, and bacteria. This report therefore focuses on the nature of infectious aerosol transmission in an attempt to determine which factors can be systematically addressed to result in proven, applied engineering approaches to the control of infectious aerosols in hospital and health care facility environments. The infectious aerosols of consideration are those that are generated as particles of respirable size by both human and environmental sources and that have the capability of remaining viable and airborne for extended periods in the indoor environment. This definition precludes skin and mucous membrane exposures occurring from splashes (rather than true aerosols) of blood or body fluids containing infectious disease agents. There are no epidemiologic or laboratory studies documenting the transmission of bloodborne virus by way of aerosols.

Aerosols↗
PubMed1999

Contribution of aerosols generated during mixing and loading of pesticides to operator inhalation exposure.

The occupational exposure resulting from the application of crop protection agents continues to be of great interest for the purposes of identifying hazards or determining safer chemical handling methods. The purpose of the present study was to identify the potential respirator exposure of a mixer/loader to chlorothalonil, with the mixing and loading operation as the only source of aerosols (particles <13 microm diameter). Three worst-case mixing/loading scenarios were simulated in the lab: (1) a spill of undiluted chlorothalonil formulation onto a dry, horizontal metal surface; (2) a spill of undiluted chlorothalonil formulation onto a rapidly rotating shaft; and (3) pouring undiluted chlorothalonil formulation into a container of water. Aerosol generation from these scenarios was compared to that resulting from atomizing dilute chlorothalonil through hydraulic nozzles. Aerosols were captured with a cascade impactor, and quantified by gas chromatography. Results indicated that simulated spill scenarios generated aerosol concentrations between 2.1 and 5.3 ng/l, which were in the same order of magnitude as, and only marginally higher than, the detection threshold (1.7 ng/l) and background levels (2.2 ng/l). In comparison, atomization of dilute chlorothalonil through a hollow cone and flat fan nozzles resulted in airborne concentrations of 354 and 96 ng/l, respectively, related to the atomization characteristics of these nozzles. Measurement of the dimensions of the aerosol cloud indicated that aerosols resulting from a spill amounted to approximately 10(-5)% of the spilled chlorothalonil. It was estimated that a male worker respiring 29 l/min would inhale approximately 0.32-0.78 ng of chlorothalonil during a typical 30 s spill, assuming a 1% transfer efficiency between the spill site and the mixer/loader. These estimates were between 10000 and 480000 times less than literature data for respiratory exposure of chlorothalonil by applicators and harvesters, suggesting that inhalation of aerosols from mixing and loading represents a minor component of overall exposure.

Adult↗
PubMed1990

Low-nicotine regenerated smoke aerosol reduces desire for cigarettes.

We have developed a method of producing an aerosol with many of the sensory qualities of cigarette smoke, but with only 3% of the tar and nicotine and none of the carbon monoxide of a typical commercial cigarette. The aerosol was generated from a suspension of 1% cigarette smoke condensate in 10% ethanol. The aerosol, generated with an ultrasonic nebulizer, resembled smoke visually but had a larger particle size than cigarette smoke (3.5 microns vs. 0.5 micron mass median diameter). Twelve smokers rated blocks of 10 puffs of aerosolized smoke solution, a popular commercial cigarette, and an unlit cigarette (control). The blocks of puffs were evaluated for sensory qualities and smoking satisfaction obtained. The rated strength of the smoke aerosol was comparable to that of the commercial cigarette. The aerosol was rated significantly more desirable and more satisfying than the control, though not as desirable as the commercial cigarette. Surprisingly, the smoke aerosol reduced self-reported desire for cigarettes as much as the commercial cigarette. This new method is a promising approach for evaluating the role of sensory cues in smoking, and it may also be useful as a clinical tool for smoking cessation.

Adult↗
PubMed2000

In the lung aerosol cyclosporine provides a regional concentration advantage over intramuscular cyclosporine.

BACKGROUND: Acute rejection remains an almost universal complication among lung transplant recipients. Refractory rejection as well as chronic systemic immunosuppression is associated with significant morbidity and mortality. Recent studies suggest that aerosol cyclosporine may address these issues by effectively preventing acute cellular rejection while maintaining low systemic drug concentrations. This study was designed to evaluate the concentrations of cyclosporine in blood and lung tissue after aerosol and intramuscular administration. METHODS: Lewis rats were divided into 4 experimental groups: Groups A (n = 33) and B (n = 30) received aerosol cyclosporine 3 and 5 mg/kg, respectively; Groups C (n = 33) and D (n = 30) received systemic cyclosporine 5 and 15 mg/kg, respectively. We used high-performance liquid chromatography to quantitate blood and lung tissue cyclosporine levels at timed intervals. We used the trapezoidal rule to approximate area under the concentration vs time curve (AUC). RESULTS: Aerosol delivery of cyclosporine resulted in higher and more rapid peak drug levels in lung tissue samples than did systemic delivery. At an equivalent 5 mg/kg dose, the cyclosporine AUC was 3 times higher with aerosol delivery than with intramuscular delivery in lung tissue (477,965 vs 157,706 ng x hour/g, respectively). The lung tissue: blood AUC ratio was highest in the aerosol groups (27.3:1 and 17.4:1) compared with the intramuscular groups (8.1:1 and 9.4:1). CONCLUSION: Local aerosol inhalation delivery of cyclosporine provides a regional advantage over systemic intramuscular therapy by providing higher peak concentrations and greater lung tissue exposure.

Administration, Inhalation↗
PubMed1971

Effects of oxygen on aerosol survival of radiation sensitive and resistant strains of Escherichia coli B.

The aerosol survivals in air and nitrogen of radiation sensitive and resistant mutants of Escherichia coli B have been determined with logarithmic and resting phase bacteria. No consistent correlation was found between radiation sensitivity and aerosol sensitivity in the strains tested. Hence, the phenotypes Fil Hcr Exr, which determine sensitivity to radiation, do not influence aerosol survival, i.e. these known mechanisms which repair radiation-induced damage do not operate in aerosol stressed E. coli. In all cases the survival in air was less than that in nitrogen particularly so for E. coli B(s-1). The effect is explained in terms of a toxic action of oxygen. Comparison of survival of log and resting phase bacteria show that log phase cells are less aerosol stable than are resting phase cells. The ability to synthesize DNA in bacteria collected from the aerosol was less than in control unstressed bacteria, and this effect was independent of the presence of oxygen. Reduced ability to synthesize DNA could have been caused by reduced metabolic activity. It is shown that two different death mechanisms occur simultaneously in aerosols at low relative humidity. One mechanism is oxygen dependent and the other oxygen independent. The former was not through a decrease in metabolic activity, whereas the latter could be.

Aerosols↗
PubMed2001

Atmospheric aerosol over Vermont: chemical composition and sources.

Aerosol chemical composition data for PM2.5 samples collected during the period from 1988 to 1995 at Underhill, VT, were analyzed. Sulfur and black carbon mass concentrations ranged from 0.01 to 6.5 microg m(-3) and from 0.05 to 2.2 microg m(-3), respectively, while the total fine aerosol mass concentration ranged from 0.2 to 51.1 microg m(-3). Seasonal variations with maxima during the summer and minima in winter/spring were observed for sulfur and the fine mass concentrations. No annual pattern was observed for black carbon. Seasonal variations for most of the other anthropogenic species had maxima in winter and spring and minima in the summer. A factor analysis method, positive matrix factorization (PMF), utilizing error estimates of the data to provide optimum data point scaling was used to obtain information about possible sources of the aerosol. An 11-factor solution was obtained. The six sources representing wood burning, coal and oil combustion, coal combustion emissions plus photochemical sulfate production, metal production plus municipal waste incineration, and emissions from motor vehicles were identified. Emissions from smelting of nonferrous metal ores, arsenic smelting, and soil particles and particles with high concentrations of Na were also identified by PMF. Potential source contribution function (PSCF) analysis combines the aerosol data with the air parcel backward trajectories. PSCF was applied to identify possible source areas and pathways that give rise to the observed high particulate mass concentrations from these 11 sources. The CAPITA Monte Carlo trajectory model was used to obtain 10 sets of 5-day air parcel back trajectories arriving every 2 h for the 7-yr period from 1988 to 1995. The PSCF plot for the black carbon factor shows high probabilities in the area surrounding the sampling site, indicating a strong local influence from residential wood combustion in northern New England and southwestern Quebec. Similar large potential source areas in the midwestern United States were identified for the two coal combustion factors. The midwestern United States was also identified as the source region for the Zn-Pb factor. The oil combustion factor was associated with the east coast of the United States. The results for the Pb-Mn factor suggests high probability over the nearby Montreal urban area and the areas in the midwestern United States. The windblown dust emissions from the areas to the north are significant contributors for the soil factor. Canadian Ni smelters are the main sources for the As factor, although there is some contribution from coal-fired power plants to the south and west of Underhill, VT. It is concluded that the combination of the two receptor modeling methods, PMF and PSCF, provides an effective way in identifying atmospheric aerosol sources and their likely locations. Emissions from different anthropogenic activities as well as secondary aerosol production are the main sources of aerosol measured in Vermont. Fuel combustion, local wood smoke, municipal waste incineration, and the secondary sulfate production collectively accounted for about 87% of the fine mass concentrations measured in Vermont.

Aerosols↗
PubMed2002

Effects of meteorological conditions on aerosol composition and mixing state in Bakersfield, CA.

Particle and meteorological instrumentation were used to characterize ambient atmospheric conditions, aerosol size distributions, aerosol mass concentrations, and single particle size and chemical composition in Bakersfield, CA for the period January 9, 1999 through January 28, 1999. The sampling period included four distinct meteorological periods of stagnation, clearing, haze, and rain. Particle number and mass concentrations were the highest during the stagnation episode when a heavy and extensive fog developed. Mass and number concentrations also approached these high levels during the haze period. Single particle size and composition data from an aerosol time-of-flight mass spectrometer (ATOFMS) are used to provide unique continuous information on the diversity in types of particles present, the effects of meteorology on particle size and composition, and the distribution of important chemical species within individual particles. Aerosol composition and mixing state are found to vary with meteorological conditions. Single particle data show that carbonaceous aerosol with secondary ammonium, nitrate, and sulfate dominate the aerosol concentration during a stagnation period with a dramatic composition shift occurring to sodium type particles during the haze period. The aerosol is internally mixed with respect to carbon, nitrate, sulfate, and ammonium during the stagnation period. The mixing state changes significantly over the haze period when much greater diversity in the associations of chemical species within individual particles occurs.

Aerosols↗
PubMed2005

Organic and inorganic aerosol below-cloud scavenging by suburban New Jersey precipitation.

Ambient aerosol size distributions and chemical composition in Princeton, NJ, were measured during a 10-day period in August 2003. Ten precipitation events during the sampling period maintained low aerosol concentrations, with an average gravimetric PM1.0 of 8.2 +/- 1.6 microg m(-3) and an average Fourier transform infrared (FTIR) spectroscopy-measured PM1.0 of 8.6 +/- 0.8 microg m(-3). A constrained factor analysis shows that the measured aerosol composition data are consistent with coal combustion and motor vehicle emissions. FTIR spectroscopy shows that the alkene fraction of organic mass (OM) was larger in the aerosol samples dominated by motor vehicle emissions than in the samples dominated by coal combustion, but the solvent-rinsing behavior was unaffected by source type. The aerosol OM was hydrophilic throughout the sampling period, with an average of 52% +/- 10% of the identified OM removed in the water-rinsing stage of the FTIR analysis. Measurements before and after rain events showed changes in particle composition and number distribution that were used to characterize the rate and chemical selectivity of particle removal processes associated with precipitation (or, in general terms, scavenging). The changes in ambient particle distributions showed an average PM1.0 below-cloud scavenging coefficient of 7 x 10(-5) +/- 3 x 10(-5) s(-1), with variability associated with chemical composition. The fraction of the aerosol OM removed in water rinses decreased during rain events, typically 55% at the start and 30% at the end of the observed rain events. These measured chemically dependent removal rates are consistent with other field measurements and can be used to improve the description of aerosol lifetimes in global models.

Aerosols↗
PubMed2006

Speciation of sulfate in size-fractionated aerosol particles using sulfur K-edge X-ray absorption near-edge structure.

X-ray absorption near-edge structure (XANES) at sulfur K-edge was used to determine the sulfate species present in size-fractionated aerosol particles based on the postedge structure after the main absorption peak in the XANES region. A comparison of the XANES spectra of reference sulfate materials and aerosol samples collected in Tsukuba in Japan clearly showed that (NH4)2SO4 was the main sulfur species in particles with a smaller diameter and CaSO4 x 2H2O (gypsum) was the main sulfur species in particles with a larger diameter. A simulation of the XANES spectra by reference materials allows us to obtain the quantitative mixing ratios of the different sulfate species present in the aerosol samples. The presence of minor sulfur species other than (NH4)2SO4 and gypsum at the surface of mineral aerosols is suggested in our simulations and by a surface-sensitive conversion electron/He-ion yield XANES. In the absence of a contribution from a large dust event, the mole concentration of gypsum in the mineral aerosol fraction (particle diameter > 1 microm) determined by XANES is similar to that of Ca which is determined independently using ion chromatography. This shows that the Ca and sulfate in the mineral aerosols are present only as gypsum. Considering that calcite is the main Ca mineral in the original material arising from an arid and semiarid area in China, it is strongly suggested that gypsum is formed in aerosol during its long-range transportation by a reaction between calcite and sulfate ions.

Absorptiometry, Photon↗
PubMed1997

The AERX aerosol delivery system.

PURPOSE: We describe the AERX aerosol delivery system, a new, bolus inhalation device that is actuated at preprogrammed values of inspiratory flow rate and inhaled volume. We report on its in vitro characterization using a particular set of conditions used in pharmacokinetic and scintigraphic studies. METHODS: Multiple doses of aerosol were delivered from single use collapsible plastic containers containing liquid formulation. The aerosol was generated by forcing the formulation under pressure through an array of 2.5 micron holes. Air was drawn through the device at 70 LPM, and the aerosol was collected onto a filter or Andersen cascade impactor. The emitted dose was quantified from the filter collection data, and the particle size distribution was obtained from the best fit log-normal distribution to the impactor data. RESULTS: 57.0 +/- 5.9% of the dose of drug placed as an aqueous solution in the 45 microL collapsible container was delivered as an aerosol (n = 40). The best fit size distribution had an MMAD = (2.95 +/- 0.06) microns and a geometric standard deviation sigma g = 1.24 +/- 0.01 (n = 6). CONCLUSIONS: The AERX aerosol delivery system generates a nearly monodisperse aerosol with the properties required for efficient and repeatable drug delivery to the lung.

Administration, Inhalation↗