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At least 649 records · Page 36Linked to original sources
PubMed1999

Pharmaceutical dry powder aerosols: correlation of powder properties with dose delivery and implications for pharmacodynamic effect.

PURPOSE: Efficient dispersion of bulk solids is critical for dry powder aerosol production which can be viewed as a sequence of events from stationary through dilated, flowing and finally dispersed particulates. The purpose of this study was to test the hypothesis that numerical descriptors of powder flow properties predict aerosol dispersion and pharmacodynamic effect. METHODS: Drug and excipient particles were prepared in size ranges suitable for inhalation drug delivery, and their physico-chemical properties were evaluated. Novel techniques (chaos analysis of dynamic angle of repose and impact force separation) were developed and utilized to measure and characterize powder flow and particle detachment from solid surfaces, respectively. Dry powder aerosol dispersion was evaluated using inertial impaction. Pharmacodynamic evaluations of bronchodilation were performed in guinea pigs, for selected formulations. RESULTS: We observed a direct correlation of powder flow with ease of particle separation (r2=0.9912) and aerosol dispersion (r2= 0.9741). In vivo evaluations indicated that formulations exhibiting a higher in vitro dose delivery resulted in a greater reduction in pulmonary inflation pressure. CONCLUSIONS: These results integrate powder behavior at various levels and indicate that numerical descriptors of powder flow accurately predict dry powder aerosol dispersion. A proportionality between aerosol dispersion and pharmacodynamic effect was observed in preliminary in vivo evaluations, which demonstrates the potential of these techniques for correlation studies between in vitro powder properties and in vivo effect.

Aerosols↗
PubMed1993

Behavior of hygroscopic pharmaceutical aerosols and the influence of hydrophobic additives.

The high temperature and relative humidity in the lung can result in the hygroscopic growth of susceptible aerosol particles or droplets. The term hygroscopic growth describes the increase in particle diameter which occurs as the result of association with water vapor. The influence of hygroscopicity upon lung deposition of aerosols has been a productive area of research in industrial hygiene, environmental sciences, and inhalation toxicology. Many pharmaceutical inhalation aerosols display hygroscopic behavior in their passage through the airways; however, the effect has been neglected. Controlling the phenomenon of hygroscopic growth and, thus, the related lung deposition of aerosols might result in the therapeutic advantage of targeting the site of action. Such an approach might also allow identification of the location of pharmacologic receptor sites in the lung. This Review discusses an approach to achieving control of hygroscopic growth of aerosol particles. Theoretical and experimental studies have indicated that inhaled particle diameters increased significantly for drugs commonly administered to the lung. The presence of certain additives, notably glycerol, cetyl alcohol, and lauric and capric acids, has been demonstrated to reduce the growth of particles under conditions approaching those in the lung. Very few quantitative studies of the nature discussed herein have appeared in the literature. It is conceivable that an aerosol particle could be fabricated of known initial size and density, and by implication, deposition characteristic, and this might be induced to follow specific growth kinetics to enhance deposition in a particular region of the lung. Thus, physical targeting of regions within the lung might be achieved.

Aerosols↗
PubMed2004

Aerosol dispersion of respirable particles in narrow size distributions using drug-alone and lactose-blend formulations.

PURPOSE: To examine the effect of formulation type on the aerosolization of respirable particles in narrow size distributions. METHODS: Aerosol dispersion of two formulation types (drug alone and 2% w/w drug-lactose blends) containing micronized or spray-dried fluticasone propionate (FP) particles (d50% = 1.3 to 9.6 microm, GSD = 1.8 to 2.2) were examined using cascade impaction at 60 l/min with low and high resistance inhaler devices: Rotahaler and Inhalator, respectively. RESULTS: The aerosol dispersion of FP particles was significantly affected by the particle size, particle type, inhaler device, and formulation type. Interactions were observed between all factors. Generally, greater powder entrainment was obtained with smaller d50%. Higher emitted doses were obtained from drug-alone formulations of spray-dried FP particles and lactose blends of micronized FP particles. Greater aerosol dispersion of spray-dried FP particles was obtained using lactose-blend formulations with d50% around 4 microm. Greater aerosol dispersion of micronized FP particles was obtained using formulations of drug alone. Larger d50% produced larger mass median aerodynamic diameters. CONCLUSIONS: Small changes in the particle size within the 1-10-microm range exerted a major influence on aerosol dispersion of jet-milled and spray-dried FP particles using drug-alone and lactose-blend formulations.

Administration, Inhalation↗
PubMed2000

Aerosolized surfactant in lung-lavaged adult rats: factors influencing the therapeutic response.

OBJECTIVE: To evaluate the effect of aerosolized modified natural surfactant in adult rats with respiratory failure. METHODS: Lung-lavaged adult rats were treated with aerosolized surfactant, aerosolized saline or a bolus of surfactant. Surfactant was labelled with dimyristoylphosphatidylcholine (DMPC) and human serum albumin was given intravenously for evaluation of lung protein leakage. Blood gases and dynamic compliance were measured intermittently. At the end of ventilation, the lungs were either fixed by vascular perfusion for histological examination or washed for determination of total phospholipids, DMPC and human albumin in the lavage fluid. RESULTS: Treatment with bolus surfactant led to a quick and sustained restoration of pre-lavage blood gas values in most animals. The response to aerosolized surfactant varied considerably, with an overall moderate improvement of gas exchange. The saline-treated group failed to show any significant recovery of lung function. No histopathological differences were found between any of the groups. On average 0.46% of total administered aerosolized surfactant could be recovered. Vascular-to-alveolar leakage of human albumin averaged 11%, with no significant differences between the groups. Final values for PaO2 were significantly correlated with total phospholipids in the lavage fluid, and inversely related to the vascular-to-alveolar leakage of albumin. CONCLUSION: Neither bolus nor aerosolized surfactant influenced lung morphology. Nebulized surfactant improved lung function but the effect was inferior to that obtained with bolus surfactant, and the outcome depended on the balance between the combined pool size of exogenous and endogenous surfactant and the vascular-to-alveolar leakage of serum protein.

Aerosols↗
PubMed2006

Aerosol delivery of Akt controls protein translation in the lungs of dual luciferase reporter mice.

Lung cancer has emerged as a leading cause of cancer death in the world; however, most of the current conventional therapies are not sufficiently effective in altering the progression of disease. Therefore, development of novel treatment approaches is needed. Although several genes and methods have been used for cancer gene therapy, a number of problems such as specificity, efficacy and toxicity reduce their application. This has led to re-emergence of aerosol gene delivery as a noninvasive method for lung cancer treatment. In this study, nano-sized glucosylated polyethyleneimine (GPEI) was used as a gene delivery carrier to investigate the effects of Akt wild type (WT) and kinase deficient (KD) on Akt-related signaling pathways and protein translation in the lungs of CMV- LucR-cMyc-IRES-LucF dual reporter mice. These mice are a powerful tool for the discrimination between cap-dependent/-independent protein translation. Aerosols containing self-assembled nano-sized GPEI/Akt WT or GPEI/Akt KD were delivered into the lungs of reporter mice through nose-only-inhalation-chamber with the aid of nebulizer. Aerosol delivery of Akt WT caused the increase of protein expression levels of Akt-related signals, whereas aerosol delivery of Akt KD did not. Furthermore, dual luciferase activity assay showed that aerosol delivery of Akt WT enhanced cap-dependent protein translation, whereas a reduction in cap-dependent protein translation by Akt KD was observed. Our results clearly showed that targeting Akt may be a good strategy for prevention as well as treatment of lung cancer. These studies suggest that our aerosol delivery is compatible for in vivo gene delivery which could be used as a noninvasive gene therapy in the future.

Aerosols↗
PubMed1999

Measurement of vapour-aerosol mixtures.

UNLABELLED: A particular problem in connection with the measurement of hazardous substances is posed by substances or groups of substances which may occur simultaneously in vapour and aerosol form. It is possible that, during sampling, the distribution of the two phases on the sampling medium is subject to changes due to vaporisation of aerosol or condensation of vapour. For workplace assessment purposes, it makes sense to consider the sum of vapour and aerosol, which never changes. Only then can the results of different sampling systems be compared. There are several ways in which vapour-aerosol mixtures can be sampled. Combining adsorption tubes or denuders with filters is the most important. Twofold requirements must be considered in the development of such sampling. METHODS: Those applying to sampling systems for aerosols as well as those for vapour sampling systems. To satisfy the requirements resulting from these substances and groups of substances, BIA's personal sampling system (PGP) was extended. In addition to the sampling head for inhalable dust (GSP), originally designed for a flow rate of 3.5 L min-1, sampling heads for 0.5, 1 and 10 L min-1 were developed. Tests were conducted on these sampling heads, which all showed compliance with the requirements defined for inhalable fraction sampling. For the combined sampling of aerosol and vapour, a system was created which allows a filter and up to three usual adsorption tubes to be loaded simultaneously. The measuring methods for alkanolamines, inorganic acids and explosives are described to illustrate the use of the above PGP extensions and the framework conditions, account of which must be taken in the sample treatment.

Aerosols↗
PubMed1994

Measurement of coarse aerosols in workplaces. A review.

Coarse aerosol fractions in workplaces are sampled if it is felt that particles of all sizes may pose a risk to health. Although the so-called 'total' aerosol has been widely used to refer to the relevant coarse fraction, practical measurement has been very dependent on the actual sampling instrument used. This in turn has led to great uncertainty about what was being measured. In the 1980s, the concept of inhalability was proposed, based on the aerosol particle size fraction that enters the human head through the nose and/or mouth during breathing. Now there is substantial agreement by most of the world's major criteria-setting bodies on a quantitative definition taking the form of a single curve describing the probability of inhalation as a function of particle aerodynamic diameter. This definition now forms a truly health-related 'yardstick' against which to assess the performances of practical sampling devices. In turn, more and more countries are beginning to adopt the new criterion for health-related aerosol measurement in their standards, replacing the old 'total' aerosol concept. Experiments in wind tunnels to investigate the performances of previous samplers for 'total' aerosol show that most of them do not satisfactorily match the new inhalability criterion. A small number of samplers designed specifically for the inhalable fraction have been proposed and are available commercially. They include samplers for both static (or area) and personal sampling.

Aerosols↗
PubMed2002

The influence of metallurgy on the formation of welding aerosols.

Recent research has indicated that insoluble ultrafine aerosols (ie., particles whose physical diameters are less than 100 nm) may cause adverse health effects due to their small size, and that toxicological response may be more appropriately represented by particle number or particle surface area. Unfortunately, current exposure criteria and the associated air-sampling techniques are primarily mass-based. Welding processes are high-temperature operations that generate substantial number concentrations of ultrafine aerosols. Welding aerosols are formed primarily through the nucleation of metal vapors followed by competing growth mechanisms such as coagulation and condensation. Experimental results and mathematical tools are presented to illustrate how welding metallurgy influences the chemical aspects and dynamic processes that initiate and evolve the resultant aerosol. This research suggests that a fundamental understanding of metallurgy and aerosol physics can be exploited to suppress the formation of undesirable chemical species as well as the amount of aerosol generated during a welding process.

Aerosols↗
PubMed2000

Pulmonary availability of isotretinoin in rats after inhalation of a powder aerosol.

Repeated oral administration of chemopreventive retinoids such as isotretinoin over extended periods of time is associated with intolerable systemic toxicity. Here isotretinoin was formulated as a powder aerosol, and its delivery to the lungs of rats was studied with the aim to explore the possibility of minimizing adverse effects associated with its oral administration. Rats received isotretinoin orally (0.5, 1 or 10 mg kg(-1)) or by inhalation (theoretical dose approximately 1 or approximately 10 mg kg(-1)) in a nose-only inhalation chamber. Isotretinoin was quantitated by high-pressure liquid chromatography in plasma and lung tissue. The ratios of mean area of concentration-vs-time curve (AUC) values in the lungs over mean AUCs in the plasma for isotretinoin following single or repeated aerosol exposure surpassed those determined for the oral route by factors of between two (single low-dose) and five (single high-dose). Similarly, the equivalent ratios for the maximal peak concentrations in lungs and plasma obtained after aerosol exposure consistently exceeded those seen after oral administration, suggesting that lungs were exposed to higher isotretinoin concentrations after aerosol inhalation than after oral administration of similar doses. Repeated high doses of isotretinoin by inhalation resulted in moderate loss of body weight, but microscopic investigation of ten tissues including lung and oesophagus did not detect any significant aerosol-induced damage. The results suggest that administration of isotretinoin via powder aerosol inhalation is probably superior to its application via the oral route in terms of achieving efficacious drug concentrations in the lungs.

Administration, Inhalation↗
PubMed2000

[Aerosolized gadolinium-DTPA for demonstration of pulmonary ventilation in magnetic resonance tomography].

PURPOSE: Magnetic resonance assessment of lung ventilation with aerosolized Gd-DTPA. METHODS: Eleven experimental procedures were carried out in a domestic pig model. The intubated pigs were aerosolized for 30 minutes with an aqueous formulation of Gd-DTPA. The contrast agent aerosol was generated by a small particle aerosol generator. Imaging was performed on a 1.5 T MR imager using a T1-weighted turbo spin echo sequence with respiratory gating (TR 141 ms, TE 8.5 ms, 6 averages, slice thickness 10 mm). Pulmonary signal intensities before and after ventilation were measured in peripheral portions of both lungs. RESULTS: Immediately after ventilation with aerosolized Gd-DTPA, the signal intensity in both lungs increased significantly in all animals with values up to 237% above baseline (mean 139% +/- 48%), but with in some cases considerable regional intra- and interindividual intensity differences. Distinctive parenchymal enhancement was readily visualized in all eleven cases with good spatial resolution. CONCLUSION: The presented data indicate that Gd-DTPA in aerosolized form can be used to demonstrate pulmonary ventilation in large animals with lung volumes comparable to man. Further experimental trials are necessary to improve reproducibility and to define the scope of this method for depicting lung disease.

Aerosols↗
PubMed2003

[MR imaging of lung ventilation with aerosolized gadolinium-chelates].

PURPOSE: To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. MATERIALS AND METHODS: Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T1-weighted turbo spin echo sequence (T(R) = 199 ms, T(E) = 8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. RESULTS: The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80 %), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35 % after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. CONCLUSION: The results of the presented phase I clinical study demonstrate the feasibility of human ventilation imaging with aerosolized Gd-chelates for the first time. More trials with a larger number of healthy subjects and patients are needed before the clinical introduction of Gd-based ventilation MR imaging of the lungs.

Adult↗
PubMed1983

Aerosol treatment of bronchoconstriction in children, with or without a tube spacer.

To assess whether an extension tube between the aerosol source and the patient improves drug-inhalation therapy in children with acute bronchoconstriction, we treated 20 children under double-blind conditions with placebo or terbutaline delivered by a conventional aerosol or an aerosol with a tube spacer. Both terbutaline treatments resulted in a significant increase in forced expiratory volume in one second, as compared with placebo (P less than 0.001), but treatment with the tube-spacer aerosol produced significantly more improvement than did treatment with the conventional aerosol (P less than 0.01). The number of errors in inhalation technique was reduced when the spacer aerosol was used, and this reduction may account for the greater improvement in the children treated with the spacer.

Aerosols↗
PubMed1989

Fate of aerosolized recombinant DNA-produced alpha 1-antitrypsin: use of the epithelial surface of the lower respiratory tract to administer proteins of therapeutic importance.

To evaluate the possibility of administering therapeutic proteins via the respiratory route, we administered an aerosol of recombinant DNA-produced human alpha 1-antitrypsin (rAAT) to anesthetized sheep and measured levels of the protein in epithelial lining fluid (ELF), lung lymph, blood, and urine. Using a nebulizer that generated aerosol droplets with a mass median aerodynamic diameter of 2.7 micron (55% of droplets were less than 3 micron, a particle size optimal for deposition on the alveolar epithelium), in vitro studies demonstrated that the aerosolized rAAT remained intact and fully functional as an inhibitor of neutrophil elastase. When aerosolized to sheep, the 45-kDa rAAT molecule diffused across the alveolar epithelium, as evidenced by its presence in lung lymph and in blood. Comparison of ELF, lymph, blood, and urine rAAT levels demonstrated that the process was concentration dependent, with highest levels in ELF and in descending concentrations with approximately 10-fold concentration differences in each consecutive compartment, respectively. Importantly, evaluation with aerosolized 125I-labeled rAAT demonstrated that the rAAT molecules that reached the lung lymph and the systemic circulation remained intact as a 45-kDa protein. These results demonstrate the feasibility of using aerosolization to the pulmonary epithelial surface to administer sizeable proteins of therapeutic interest, thus circumventing the necessity of the traditional parenteral modes of administration of such molecules.

Absorption↗
PubMed2004

Aerosol-induced Mycoplasma synoviae arthritis: the synergistic effect of infectious bronchitis virus infection.

The effect of infectious bronchitis virus (IBV) infection (10(4.5) median embryo infective dose per chick) on the induction of Mycoplasma synoviae arthritis was investigated. Mycoplasma-free brown layer pullets, approximately 5 weeks old, were exposed to an aerosol dose of > or =10(2-3) colony-forming units (CFU) of M. synoviae alone or 3 days after inoculation of a field strain of IBV (D1466) by the ocular-nasal route. Chicks injected intravenously with 10(9) CFU M. synoviae served as positive controls. Thirty-one per cent of chicks receiving M. synoviae aerosol alone developed arthritis compared with 50% of those co-infected with IBV. Ninety-five per cent of positive control birds developed arthritis. In a repeat experiment an additional group was exposed to M. synoviae aerosol 3 days after infection with IBV M41 strain. These birds also received two aerosol doses of M. synoviae 14 days apart (> or =10(0-1) CFU/bird initially and > or =10(1-3) after 14 days). Chicks injected intravenously with 10(6) CFU M. synoviae acted as positive controls. Fifty per cent of the positive controls were re-inoculated intravenously (10(8) CFU) after 14 days. Twenty-one per cent of chicks infected with M. synoviae aerosol developed arthritis compared with 33% of those co-infected with IBV D1466, and 55% of those co-infected with IBV M41. After the single intravenous, low-dose M. synoviae inoculation 11% of birds developed joint lesions, whereas 70% of those receiving the second inoculation developed lesions. These results suggest that IBV may enhance M. synoviae arthritis after aerosol exposure and that the incidence of joint pathology depends on the strain of IBV.

Aerosols↗
PubMed2001

A nonhuman primate aerosol deposition model for toxicological and pharmaceutical studies.

Nonhuman primates may be used as human surrogates in inhalation exposure studies to assess either the (1) adverse health effects of airborne particulate matter or (2) therapeutic effects of aerosolized drugs and proteins. Mathematical models describing the behavior and fate of inhaled aerosols may be used to complement such laboratory investigations. For example, the optimal conditions, in terms of ventilatory parameters (e.g., breathing frequency and tidal volume) and aerosol characteristics (e.g., geometric size and density), necessary to target drug delivery to specific sites within the respiratory tract may be estimated a priori with models. In this work a mathematical description of the rhesus monkey (Macaca mulatta) lung is presented for use with an aerosol deposition model. Deposition patterns of 0.01- to 5-microm-diameter monodisperse aerosols within lungs were calculated for 3 monkey lung models (using different descriptions of alveolated regions) and compared to human lung results obtained using a previously validated mathematical model of deposition physics. Our findings suggest that there are significant differences between deposition patterns in monkeys and humans. The nonhuman primates had greater exposures to inhaled substances, particularly on the basis of deposition per unit airway surface area. However, the different alveolar volumes in the rhesus monkey models had only minor effects on aerosol dosimetry within those lungs. By being aware of such quantitative differences, investigators can employ the respective primate models (human and nonhuman) to more effectively design and interpret the results of future inhalation exposure experiments.

Aerosols↗
PubMed1999

Increased exposure to pollutant aerosols under high voltage power lines.

PURPOSE: To assess increased exposure to airborne pollutants near power lines by investigating theoretically and experimentally the behaviour of 222Rn decay product marker aerosols in the 50 Hz electric field under power lines. MATERIALS AND METHODS: The behaviour of aerosols in outdoor air including those carrying 222Rn decay products was modelled theoretically in the presence of an AC field. TASTRAK alpha-particle spectroscopy was used to characterize 218Po and 214Po aerosols outdoors. Sampling points were chosen along a line at right angles up to 200 m from a number of high voltage power (transmission) lines. Each sampling point comprised an arrangement of mutually orthogonal TASTRAK detectors. Exposures were carried out at different power line locations in various weather conditions. RESULTS: The model predicts a two- to three-fold increase in deposition of aerosols on spherical surfaces mimicking the human head under high voltage power lines. Experimental measurements using detectors mounted on grounded metal spheres showed an enhanced deposition of both 218Po and 214Po aerosols. Enhanced 218Po deposition on 400 kV lines ranged from 1.96+/-0.15 to 2.86+/-0.32. Enhanced 214Po deposition on 275 kV and 132 kV lines were 1.43+/-0.07 and 1.11+/-0.21, respectively, where the latter value was not significant. CONCLUSIONS: The observations demonstrate a mode of increased exposure to pollutant aerosols under high voltage power lines by increased deposition on the body. The total (indoor + outdoor) 218Po and 214Po dose to the basal layer of facial skin is estimated to be increased by between 1.2 and 2.0 for 10% of time spent outdoors under high voltage power lines.

Aerosols↗
PubMed2002

Relationship between lead levels on painted surfaces and percent lead in the particles aerosolized during lead abatement.

Quantifying airborne lead on lead abatement work sites is critical in assessing worker lead exposures. Airborne lead levels depend on both the concentration of aerosolized particles and the percent lead in those particles. The lead level on the painted surface being abated may affect the percent lead in aerosolized particles. Experiments were performed in the University of Cincinnati Environmental Test Chamber (volume approximately 24.3 m3) using wood doors painted with lead-based paint. Three methods were used for paint removal: dry scraping, wet scraping, and dry machine sanding. Particles aerosolized during lead abatement activities were collected on filters using the Button Personal Inhalable Aerosol Samplers (SKC Inc., Eighty Four, PA) mounted in the workers' breathing zone. The filters were subsequently analyzed for percent lead in the particles. A portable X-ray fluorescence (XRF) instrument (NITON-700, NITON Inc., Bedford, MA) was used to measure surface lead levels of the doors. The accuracy of the XRF instrument was verified by testing standard reference materials prepared by the National Institute of Standards and Technology (NIST) and by Princeton Gamma Tech Inc. It was also verified by relating XRF results from painted door surfaces to laboratory lead analysis data obtained from paint chip samples taken from the same painted surfaces (r2 = 0.81, p < 0.001). A highly significant relationship (r2 = 0.83, p < 0.001) was found between the XRF readings and the percent lead in the particles aerosolized during dry scraping. No significant relationship was found for wet scraping (r2 = 0.09, p = 0.56) or dry machine sanding (r2 = 0.002, p = 0.92). The relationship between surface lead levels and percent lead in particles was found to be dependent on the paint removal method. This variation was attributed to the difference in water absorption property of the paint layers and the different particle aerosolization mechanisms inherent in each paint removal method.

Aerosols↗
PubMed2000

Size distribution and sources of aerosol in Launceston, Australia, during winter 1997.

As part of a pilot study into the chemical and physical properties of Australian fine particles, a suite of aerosol samples was collected at Ti Tree Bend in Launceston, Tasmania, during June and July 1997. This period represents midwinter in the Southern Hemisphere, a period when aerosol sources in Launceston are dominated by smoke from domestic wood burning. This paper describes the results from this measurement campaign, with the aim of assessing the effect of wood smoke on the chemical and physical characteristics of ambient aerosol. A micro orifice uniform deposit impactor (MOUDI) was used to measure the size distributions of the aerosol from 0.05 to 20 microns aerodynamic diameter. Continuous measurements of fine particle mass were made using a PM2.5 tapered element oscillating microbalance (TEOM) and light scattering coefficients at 530 nm were measured with nephelometers. Mass size distributions tended to be bimodal, with the diameter of the dominant mode tending to smaller sizes with increases in total mass. Non-sea salt potassium and polycyclic aromatic hydrocarbons (PAHs) were used as chemical tracers for wood smoke. Wood smoke was found to increase absolute particle mass (enough to regularly exceed air quality standards), and to concentrate mass in a single mode below 1 micron aerodynamic diameter. The acid-base equilibrium of the aerosol was altered by the wood smoke source, with free acidity hydrogen ion, non-sea salt sulfate, and ammonium concentrations being higher and the concentration of all species, including nitrate (to differing extents), focused in the fine particle size ranges. The wood smoke source also heavily influenced the aerosol scattering efficiency, adding to a strong diurnal cycle in both mass concentration and light scattering.

Aerosols↗