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Aim: The aim of this paper is to present the construction and principle of operation of condensed aerosol generators, as well as a review of their selected characteristics, confirmed in the process of assessment and verification of constancy of performance. The paper describes selected laboratory tests, including those specific to Group A, B and C fires. Introduction: Fixed firefighting systems, in addition to detection systems (fire alarm system) and alarm systems (voice evacuation systems), are one of the pillars of the safety of today's erected, increasingly complex buildings. However, unlike these detection and alarm systems, fire extinguishing systems based on condensed aerosol generators focus on providing an adequate level of protection for property, as they are dedicated to spaces that are not normally occupied. For this reason, emphasis is placed on the reliability of the generators, whose only task is to trigger appropriately at a specific time and fill the protected area with aerosol. Methodology: The theoretical research, such as analysis of literature and legal documents, synthesis, generalisation, inference, comparison and analogy, was used in the development of the paper. A review of selected characteristics validated in the process of assessment and verification of constancy of performance of the analysed products was carried out. Research processes relating to selected parameters of the generators and inherent in the conformity assessment of construction products are presented. Conclusions: It should be noted that, irrespective of their main purpose, condensed aerosol generators, which are a key component of aerosol fire extinguishing kits, can be crucial not only with regard to the safety of the buildings themselves, but also of their users, influencing the containment of a fire in the extinguishing zone where they are installed. Also, important is the awareness of owners and managers of building structures equipped with condensed aerosol generators. Their particular attention should be directed to the specifics of the generator itself and their knowledge of its operating principles. In the next stages of the work, it will be crucial to define the basics related to the connection of the generators to the installation forming a fixed firefighting system, to identify and describe issues related to design, installation and maintenance, and to identify the risks related to the potential exposure of the users of built structures to the extinguishing aerosol.

Aim: The purpose of this paper is to review selected requirements for the design, installation, and maintenance of fixed fire extinguishing systems based on condensed aerosol generators, which are the most important component of aerosol fire extinguishing systems. Particular attention was paid to the hazards associated with the pH and corrosiveness of aerosol deposits on electronics, as well as the equally important hazards to humans associated with the size of the extinguishing aerosol particles. Introduction: Fixed aerosol fire extinguishing devices and aerosol fire extinguishing kits, whose basic component is a condensed aerosol generator, are one example of specific solutions related to ensuring the safety of buildings. However, their design and operation differ from extinguishing systems that use extinguishing agents such as gases (e.g., CO2, N2, fluoroketones) or water-based agents (water, foam, or water mist). Therefore, the design, installation, and maintenance of such systems require special expertise and knowledge of potential hazards, including, for example, the entrapment of users or facility personnel in the extinguishing zone where aerosol discharge may occur. Methodology: The article draws on theoretical research, such as: analysis of literature and legal documents, synthesis, generalization, inference, comparison, and analogy. Conclusions: Condensed aerosol generators, which are an important component of aerosol fire extinguishing systems alongside other fire safety systems, have an impact on both the safety of buildings and the safety of users staying in the building. Considering the risks associated with aerosol discharge – reduced visibility, toxicity, thermal hazards – the competence of entities that declare to provide services in this area is very important in the design, installation, and maintenance of such systems. At later stages of the work, it will be crucial to determine the methods and possibilities for efficient and rapid removal of residues after the discharge of fire extinguishing aerosol in the protected extinguishing zone, so that the protected room can be restored to use as quickly as possible. It will be equally important to determine methods for removing aerosol residues from equipment, including, in particular, broadly understood electronics. The effective and safe use of SUG-A technologies requires not only knowledge of their physicochemical properties, but also a thorough risk assessment, knowledge of applicable regulations and standards, and appropriate qualifications of those involved in the design and maintenance of the installation.

The effect of nanogel colloidal and dissolved organic matter <0.2 μm, secreted by marine biota, on the hygroscopic growth and droplet activation behaviour of the primary marine aerosol was studied. Seawater proxies were prepared by the combination of artificial seawater devoid of marine organics and natural seawater enriched in organic exudate released by laboratory-grown phytoplankton cultures, as described in a companion paper. The primary aerosol was produced by bubble bursting, using a plunging multijet system as an aerosol generator. The aerosol generated from seawater proxies enriched with marine exudate presented organic volume fractions on the order of 8–37%, as derived by applying a simple mixing rule. The hygroscopic growth and cloud condensation nuclei (CCN) activity of the marine organics-enriched particles where 9–17% and 5–24% lower, respectively, than those of the aerosol produced from artificial seawater devoid of exudate. Experiments in a companion paper indicated that the cloud nuclei formation could be enhanced in diatom bloom areas because of the increase in the primary particle production induced by marine organics. The experiments in the present study, however, indicate that the impacts of such an enhancement would be counteracted by the reduction in the CCN activity of the primary particles enriched in marine organics. The extent of the effect of the biogenic matter on the particle behaviour was dependent on the seawater organic concentration and type of algal exudate. Aerosol produced from seawater proxies containing diatomaceous exudate presented higher hydrophobicity and lower CCN activity than those enriched with nanoplankton exudate. The organic fraction of the particles was found to correlate with the seawater organic concentration, without observing saturation of the particle organic mass fraction even for unrealistically high organic matter concentration in seawater. These findings are indicative that discrepancies on the composition of the primary aerosol between different studies could partly be explained by the difference in the nature and concentration of the organic matter in the source seawater employed. Consistently across the experiments, theoretical analysis based on the Köhler model predicted a reduction in the primary marine aerosol CCN activity upon the incorporation of marine organics into the particle composition. This effect is consequence of the replacement of small inorganic sea salt molecules by large molar mass organic molecules, together with a moderate suppression of the surface tension at the point of activation of 5–0.5%, which leads to a dominance of the reduction in the dissolved solute in the Raoult term.

Owing to its ability to produce dense thick-films at room temperature directly from a ceramic powder, the Aerosol Deposition Method (AD) possesses a unique feature in ceramics processing. For this technology, the aerosol generation of particles is a decisive part of reliable process control. However, there has only been a small amount of work published addressing this topic. In this work, we compare the aerosolization and deposition behavior of a fluidized bed generator with an aerosol generator with the rotary brush principle. While film properties very much depend on deposition time for the fluidized bed generator, films produced with the brush generator show a constant film profile, and their film thickness correlates with the controllable aerosol concentration and the duration of deposition. This type of aerosol generation may improve the setup towards a more reliable AD process.

The effect of biogenic dissolved and colloidal organic matter on the production of submicron primary sea-spray aerosol was investigated via the simulation of bubble bursting in seawater enriched with phytoplankton-released organics. Seawater samples collected along a transect off the West African coast during the RHaMBLe cruise (RRS Discovery cruise D319), conducted as part of the SOLAS UK program, were analysed in order to identify the dominant oceanic algal species in a region of high biological activity. Cultures of microalgal strains representative of the species found in the collected seawater were grown in order to produce natural bioexudate. Colloidal plus dissolved organic fraction in this material remaining after <0.2 μm filtration was employed to prepare organic-enriched seawater proxies for the laboratory production of marine aerosol using a plunging-waterjet system as an aerosol generator. Submicron size distributions of aerosols generated from different organic monolayers and seawater proxies enriched with biogenic exudate were measured and compared with blanks performed with artificial seawater devoid of marine organics. A shift of the aerosol submicron size distribution toward smaller sizes and an increase in the production of particles with dry diameter (Dp0)<100 nm was repeatedly observed with increasing amounts of diatomaceous bioexudate in the seawater proxies used for aerosol generation. The effect was found to be sensitive to the organic carbon concentration in seawater and the algal exudate type. Diatomaceous exudate with organic carbon concentration (OC<0.2 μm) >175 μM was required to observe a significant impact on the size distribution, which implies that effects are expected to be substantial only in high biological activity areas abundant with diatom algal populations. The laboratory findings were in agreement with analogous bubble-bursting experiments conducted with unfiltered oceanic seawater collected during the RHaMBLe cruise, which revealed a higher production of particles with Dp0<100 nm at regions with high biological activity. These findings suggest that the increase in the atmospheric aerosol modal sizes from winter to summer, reported by long-term observations in North Atlantic waters, is not directly due to an impact of the higher primary organic matter production occurring during warm periods. A novel sub-micrometric size-resolved source flux function, explicitly defined as a function of the diatomaceous exudate concentration, was derived from the size distribution measurements and the estimation of the fractional whitecap coverage. According to the defined parameterisation, a 300 μM OC<0.2 μm concentration of diatomaceous exudate in seawater produces an overall increment in the total source particle flux of ~20% with respect to the organics-free seawater case. The effect increases with decreasing particle size for Dp0<100 nm, resulting in multiplicative factors between 1.02–2 with respect to the particle flux generated from seawater devoid of marine organics. The total source flux derived from the presented parameterisation was compared to recent definitions of sea-spray source fluxes based on laboratory and field observations in the literature.

The paper focuses on ground-based aerosol generators, which become increasingly often used in the world practice of cloud seeding to control precipitation and prevent hailstorms. The results of theoretical and experimental estimates of the reagent distribution in the atmospheric boundary layer during the operation of ground-based aerosol generators are given. It is shown that the concentration of silver iodide recorded in the atmosphere was above background values to a height of 1200 m at distances from 3 to 9 km from the generator installation site. The results of the experiment on the precipitation enhancement in the Republic of Crimea demonstrated that when clouds passed over generators, the height of their tops, their maximum reflectivity, and precipitation intensity increased, which indicates a positive effect of generators on clouds. Conclusions are made about the prospects of using ground-based aerosol generators as a complement to the aircraft method, especially when seeding clouds at night and in the regions with mountain terrain.

Vaping (inhalation of electronic cigarette-generated aerosol) is a public health concern. Due to recent spikes in adolescent use of electronic cigarettes (ECIGs) and vaping-induced illnesses, demand for scientific inquiry into the physiological effects of electronic cigarette (ECIG) aerosol has increased. For such studies, standardized and consistent aerosol production is required. Many labs generate aerosol by manually activating peristaltic pumps and ECIG devices simultaneously in a predefined manner. The tedium involved with this process (large puff number over time) and risk of error in keeping with puff topography (puff number, duration, interval) are less than optimal. Furthermore, excess puffing on an ECIG device results in battery depletion, reducing aerosol production, and ultimately, its chemical and physical nature. While commercial vaping machines are available, the cost of these machines is prohibitive to many labs. For these reasons, an economical and programmable ECIG aerosol generator, capable of generating aerosol from two atomizers simultaneously, was fabricated, and subsequently validated. Validation determinants include measurements of atomizer temperatures (inside and outside), electrical parameters (current, resistance and power) of the circuitry, aerosol particle distribution (particle counts and mass concentrations) and aerosol delivery (indexed by nicotine recovery), all during stressed conditions of four puffs/minute for 75 min (i.e., 300 puffs). Validation results indicate that the ECIG aerosol generator is better suited for experiments involving ≤100 puffs. Over 100 puffs, the amount of variation in the parameters measured tends to increase. Variations between channels are generally higher than variations within a channel. Despite significant variations in temperatures, electrical parameters, and aerosol particle distributions, both within and between channels, aerosol delivery remains remarkably stable for up to 300 puffs, yielding over 25% nicotine recovery for both channels. In conclusion, this programmable, dual-channel ECIG aerosol generator is not only affordable, but also allows the user to control puff topography and eliminate battery drain of ECIG devices. Consequently, this aerosol generator is valid, reliable, economical, capable of using a variety of E-liquids and amenable for use in a vast number of studies investigating the effects of ECIG-generated aerosol while utilizing a multitude of puffing regimens in a standardized manner.

This study investigates a real-time handheld bioaerosol monitoring system for the detection of biological particles using UV-LED and light-induced fluorescence technology. Biological particles produce both scattering and fluorescence signals simultaneously, which can help distinguish them from general particles. The detected scattering, fluorescence, and simultaneous signals are then converted into photon signals and categorized based on predetermined criteria. A reliable biological particle generator was required to validate the performance of the system. This study explores the use of an M13 bacteriophage as a virus simulant of biological agents and employs a customized inkjet aerosol generator to produce M13 bacteriophage aerosols of a specific size by controlling the concentration of M13. We confirmed that micro-sized, narrowly dispersed M13 aerosols were efficiently generated. Additionally, we confirmed the performance of this real-time handheld bioaerosol monitoring system by detecting viruses.

Abstract In selected patients, noninvasive positive pressure ventilation (NIPPV) with a facemask is now commonly employed as the first choice for providing mechanical ventilation in the intensive care unit (ICU). Aerosol therapy for treatment of acute or acute-on-chronic respiratory failure in this setting may be delivered by pressurized metered-dose inhaler (pMDI) with a chamber spacer and facemask or nebulizer and facemask. This article reviews the host of factors influencing aerosol delivery with these devices during NIPPV. These factors include (1) the type of ventilator, (2) mode of ventilation, (3) circuit conditions, (4) type of interface, (5) type of aerosol generator, (6) drug-related factors, (7) breathing parameters, and (8) patient-related factors. Despite the impediments to efficient aerosol delivery because of continuous gas flow, high inspiratory flow rates, air leaks, circuit humidity, and patient-ventilator asynchrony, significant therapeutic effects are achieved after inhaled bronchodilator administration to patients with asthma and chronic obstructive pulmonary disease. Similarly to invasive mechanical ventilation, careful attention to the technique of drug administration is required to optimize therapeutic effects of inhaled therapies during NIPPV. Assessment of the patient's ability to tolerate a facemask, the level of respiratory distress, hemodynamic status, and synchronization of aerosol generation with inspiratory airflow are important factors contributing to the success of aerosol delivery during NIPPV. Further research into novel delivery methods, such as the use of NIPPV with nasal cannulae, could enhance the efficiency, ease of use, and reproducibility of inhalation therapy during noninvasive ventilation.

Fine particles are widely used in many industrial fields, and there are many techniques applied for these particles, like electroplating, and chemical and physical vapor deposition. However, in the food and pharmaceutical industries, most coating processes conducted with fluidized bed use core particles with a diameter larger than 200 μm, otherwise agglomerates are formed. This study contributes to the development of a new coating process for fine particles with diameters of around 50 μm. The innovation lies in the combined use of a Wurster fluidized bed and a novel aerosol atomizer. The feasibility of the operation is based on the application of the aerosol atomizer, which generates droplets smaller than 1 μm in diameter. A series of experiments with different coating solutions and glass beads in a 150 mm fluidized bed fed with droplet aerosol supplied from the cone chamber bottom is presented. The quality of the coating product is analyzed by scanning electron microscopy and CAMSIZER®. In this way, the influence of different conditions and core material properties on the product quality were determined. Experimental results showed the coating layer quality getting worse as coating solution viscosity became lower, meanwhile moderate process temperature was found to enhance coating layer formation and quality of that. It was also observed that lower aerosol feed rates help improve the yield of the process.