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Journal of Otolaryngology - Head & Neck... May 2020Aerosol generating medical procedures (AGMPs) present risks to health care workers (HCW) due to airborne transmission of pathogens. During the COVID-19 pandemic, it is... (Review)
Review
BACKGROUND
Aerosol generating medical procedures (AGMPs) present risks to health care workers (HCW) due to airborne transmission of pathogens. During the COVID-19 pandemic, it is essential for HCWs to recognize which procedures are potentially aerosolizing so that appropriate infection prevention precautions can be taken. The aim of this literature review was to identify potential AGMPs in Otolaryngology - Head and Neck Surgery and provide evidence-based recommendations.
METHODS
A literature search was performed on Medline, Embase and Cochrane Review databases up to April 3, 2020. All titles and abstracts of retrieved studies were evaluated and all studies mentioning potential AGMPs were included for formal review. Full text of included studies were assessed by two reviewers and the quality of the studies was evaluated. Ten categories of potential AGMPs were developed and recommendations were provided for each category.
RESULTS
Direct evidence indicates that CO2 laser ablation, the use of high-speed rotating devices, electrocautery and endotracheal suctioning are AGMPs. Indirect evidence indicates that tracheostomy should be considered as potential AGMPs. Nasal endoscopy and nasal packing/epistaxis management can result in droplet transmission, but it is unknown if these procedures also carry the risk of airborne transmission.
CONCLUSIONS
During the COVID-19 pandemic, special care should be taken when CO2 lasers, electrocautery and high-speed rotating devices are used in potentially infected tissue. Tracheal procedures like tracheostomy and endotracheal suctioning can also result in airborne transmission via small virus containing aerosols.
Topics: Aerosols; Betacoronavirus; COVID-19; Coronavirus Infections; Humans; Infection Control; Infectious Disease Transmission, Patient-to-Professional; Otorhinolaryngologic Diseases; Otorhinolaryngologic Surgical Procedures; Pandemics; Pneumonia, Viral; Practice Guidelines as Topic; SARS-CoV-2
PubMed: 32375884
DOI: 10.1186/s40463-020-00425-6 -
Environmental Science & Technology Sep 2021A large fraction of atmospheric aerosols can be characterized as primary organic aerosol (POA) and secondary organic aerosol (SOA). Knowledge of the phase behavior, that...
A large fraction of atmospheric aerosols can be characterized as primary organic aerosol (POA) and secondary organic aerosol (SOA). Knowledge of the phase behavior, that is, the number and type of phases within internal POA + SOA mixtures, is crucial to predict their effect on climate and air quality. For example, if POA and SOA form a single phase, POA will enhance the formation of SOA by providing organic mass to absorb SOA precursors. Using microscopy, we studied the phase behavior of mixtures of SOA proxies and hydrocarbon-like POA proxies at relative humidity (RH) values of 90%, 45%, and below 5%. Internal mixtures of POA and SOA almost always formed two phases if the elemental oxygen-to-carbon ratio (O/C) of the POA was less than 0.11, which encompasses a large fraction of atmospheric hydrocarbon-like POA from fossil fuel combustion. SOA proxies mixed with POA proxies having 0.11 ≤ O/C ≤ 0.29 mostly resulted in particles with one liquid phase. However, two liquid phases were also observed, depending on the type of SOA and POA surrogates, and an increase in phase-separated particles was observed when increasing the RH in this O/C range. The results have implications for predicting atmospheric SOA formation and policy strategies to reduce SOA in urban environments.
Topics: Aerosols; Air Pollutants; Carbon; Hydrocarbons; Oxygen
PubMed: 34473474
DOI: 10.1021/acs.est.1c02697 -
International Journal of Environmental... Feb 2022Many electronic cigarette manufacturers have offered different types of "high-end mods" that allow for controlled heating of the e-liquid. However, the controlled...
Many electronic cigarette manufacturers have offered different types of "high-end mods" that allow for controlled heating of the e-liquid. However, the controlled heating condition can drastically alter the inhaled aerosols' physical properties and chemical substances, causing potential health risks. To investigate the contribution of heating on aerosol properties, we used four common power settings in the mods to conduct a physicochemical analysis. Our data showed that the aerosol mass and nicotine content in the aerosols increased at high power. Additionally, high power led to aerosolization of a viscous component in the e-liquid, increasing the viscosity of aerosol. However, the pH of the aerosol was constant regardless of the applied power. In addition, high-power operation made nicotine prone to oxidation, resulting in the color of the aerosol turning yellow. Lastly, we demonstrated that e-cigarette aerosol could contain various metals, including aluminum, arsenic, cadmium, chromium, copper, iron, magnesium, nickel, lead, and zinc. Even though these metal contents proportionally increased with the power setting, they remained far below the recommended exposure limits. Our finding demonstrates that the heating conditions of the e-cigarette change the physicochemical properties of the aerosols and their metal contents, thereby possibly affecting users' oral and respiratory systems.
Topics: Aerosols; Electronic Nicotine Delivery Systems; Heating; Nicotine; Vaping
PubMed: 35162914
DOI: 10.3390/ijerph19031892 -
Nature Communications Aug 2022Atlantic hurricane activity experienced a pronounced lull during the 1970s and 1980s. The current explanation that anthropogenic aerosol radiative forcing cooled the sea...
Atlantic hurricane activity experienced a pronounced lull during the 1970s and 1980s. The current explanation that anthropogenic aerosol radiative forcing cooled the sea surface locally fails to capture the magnitude of this large decrease in activity. To explain this hurricane drought, we propose that the radiative effects of sulfate aerosols from Europe and North-America decreased precipitation in the Sahara-Sahel region, leading to an enhancement of dust regional emissions and transport over the Atlantic. This dust in turn enhanced the local decrease of sea-surface temperature and of hurricane activity. Here, we show that dust emissions from the Sahara peaked in phase with regional sulfate aerosol optical thickness and Sahel drought conditions, and that dust optical depth variations alone can explain nearly half of the sea-surface temperature depression in the 1970s and 1980s.
Topics: Aerosols; Cyclonic Storms; Droughts; Dust; Sulfates
PubMed: 36038579
DOI: 10.1038/s41467-022-32779-y -
The European Respiratory Journal Jun 1996
Review
Topics: Aerosols; Bronchi; Bronchial Hyperreactivity; Humans; Particle Size
PubMed: 8804925
DOI: 10.1183/09031936.96.09061118 -
Journal of Periodontology Sep 2020The risk of transmitting airborne pathogens is an important consideration in dentistry and has acquired special significance in the context of recent respiratory disease... (Review)
Review
The risk of transmitting airborne pathogens is an important consideration in dentistry and has acquired special significance in the context of recent respiratory disease epidemics. The purpose of this review, therefore, is to examine (1) what is currently known regarding the physics of aerosol creation, (2) the types of environmental contaminants generated by dental procedures, (3) the nature, quantity, and sources of microbiota in these contaminants and (4) the risk of disease transmission from patients to dental healthcare workers. Most dental procedures that use ultrasonics, handpieces, air-water syringes, and lasers generate sprays, a fraction of which are aerosolized. The vast heterogeneity in the types of airborne samples collected (spatter, settled aerosol, or harvested air), the presence and type of at-source aerosol reduction methods (high-volume evacuators, low volume suction, or none), the methods of microbial sampling (petri dishes with solid media, filter paper discs, air harvesters, and liquid transport media) and assessment of microbial bioload (growth conditions, time of growth, specificity of microbial characterization) are barriers to drawing robust conclusions. For example, although several studies have reported the presence of microorganisms in aerosols generated by ultrasonic scalers and high-speed turbines, the specific types of organisms or their source is not as well studied. This paucity of data does not allow for definitive conclusions to be drawn regarding saliva as a major source of airborne microorganisms during aerosol generating dental procedures. Well-controlled, large-scale, multi center studies using atraumatic air harvesters, open-ended methods for microbial characterization and integrated data modeling are urgently needed to characterize the microbial constituents of aerosols created during dental procedures and to estimate time and extent of spread of these infectious agents.
Topics: Aerosols; Air Microbiology; Dental Scaling; Humans; Saliva; Suction
PubMed: 32662070
DOI: 10.1002/JPER.20-0395 -
Frontiers in Cellular and Infection... 2012Historically, pharmaceutical aerosols have been employed for the treatment of obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease, but... (Review)
Review
Historically, pharmaceutical aerosols have been employed for the treatment of obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease, but in the past decades their use has been expanded to treat lung infections associated with cystic fibrosis and other respiratory diseases. Tuberculosis (TB) is acquired after inhalation of aerosol droplets containing the bacilli from the cough of infected individuals. Even though TB affects other organs, the lungs are the primary site of infection, which makes the pulmonary route an ideal alternative route to administer vaccines or drug treatments. Optimization of formulations and delivery systems for anti-TB vaccines and drugs, as well as the proper selection of the animal model to evaluate those is of paramount importance if novel vaccines or drug treatments are to be successful. Pharmaceutical aerosols for patient use are generated from metered dose inhalers, nebulizers, and dry powder inhalers (DPIs). In addition to the advantages of providing more efficient delivery of the drug, low cost, and portability, pharmaceutical dry powder aerosols are more stable than inhalable liquid dosage forms and do not require refrigeration. Methods to manufacture dry powders in respirable sizes include micronization, spray drying, and other proprietary technologies. Inhalable dry powders are characterized in terms of their drug content, particle size, and dispersibility to ensure deposition in the appropriate lung region and effective aerosolization from the device. These methods will be illustrated as they were applied for the manufacture and characterization of powders containing anti-tubercular agents and vaccines for pulmonary administration. The influence of formulation, selection of animal model, method of aerosol generation, and administration on the efficacy demonstrated in a given study will be illustrated by the evaluation of pharmaceutical aerosols of anti-TB drugs and vaccines in guinea pigs by our group.
Topics: Administration, Inhalation; Aerosols; Animals; Antitubercular Agents; Disease Models, Animal; Guinea Pigs; Technology, Pharmaceutical; Treatment Outcome; Tuberculosis; Tuberculosis Vaccines
PubMed: 22973562
DOI: 10.3389/fcimb.2012.00118 -
Analytical Chemistry Aug 2021Aerosols dispersed and transmitted through the air (e.g., particulate matter pollution and bioaerosols) are ubiquitous and one of the leading causes of adverse health...
Aerosols dispersed and transmitted through the air (e.g., particulate matter pollution and bioaerosols) are ubiquitous and one of the leading causes of adverse health effects and disease transmission. A variety of sampling methods (e.g., filters, cyclones, and impactors) have been developed to assess personal exposures. However, a gap still remains in the accessibility and ease-of-use of these technologies for people without experience or training in collecting airborne samples. Additionally, wet scrubbers (large non-portable industrial systems) utilize liquid sprays to remove aerosols from the air; the goal is to "scrub" (i.e., clean) the exhaust of industrial smokestacks, not collect the aerosols for analysis. Inspired by wet scrubbers, we developed a device fundamentally different from existing portable air samplers by using aerosolized microdroplets to capture aerosols in personal spaces (e.g., homes, offices, and schools). Our aerosol-sampling device is the size of a small teapot, can be operated without specialized training, and features a winding flow path in a supersaturated relative humidity environment, enabling droplet growth. The integrated open mesofluidic channels shuttle coalesced droplets to a collection chamber for subsequent sample analysis. Here, we present the experimental demonstration of aerosol capture in water droplets. An iterative study optimized the non-linear flow manipulating baffles and enabled an 83% retention of the aerosolized microdroplets in the confined volume of our device. As a proof-of-concept for aerosol capture into a liquid medium, 0.5-3 μm model particles were used to evaluate aerosol capture efficiency. Finally, we demonstrate that the device can capture and keep a bioaerosol (bacteriophage MS2) viable for downstream analysis.
Topics: Aerosols; Air Microbiology; Environmental Monitoring; Humans; Levivirus; Particle Size; Particulate Matter
PubMed: 34379402
DOI: 10.1021/acs.analchem.1c01296 -
Environmental Health Perspectives Feb 2018Electronic cigarettes (e-cigarettes) generate an aerosol by heating a solution (e-liquid) with a metallic coil. Whether metals are transferred from the coil to the...
BACKGROUND
Electronic cigarettes (e-cigarettes) generate an aerosol by heating a solution (e-liquid) with a metallic coil. Whether metals are transferred from the coil to the aerosol is unknown.
OBJECTIVE
Our goal was to investigate the transfer of metals from the heating coil to the e-liquid in the e-cigarette tank and the generated aerosol.
METHODS
We sampled 56 e-cigarette devices from daily e-cigarette users and obtained samples from the refilling dispenser, aerosol, and remaining e-liquid in the tank. Aerosol liquid was collected via deposition of aerosol droplets in a series of conical pipette tips. Metals were reported as mass fractions (μg/kg) in liquids and converted to mass concentrations (mg/m) for aerosols.
RESULTS
Median metal concentrations (μg/kg) were higher in samples from the aerosol and tank vs. the dispenser (all <0.001): 16.3 and 31.2 vs. 10.9 for Al; 8.38 and 55.4 vs. <0.5 for Cr; 68.4 and 233 vs. 2.03 for Ni; 14.8 and 40.2 vs. 0.476 for Pb; and 515 and 426 vs. 13.1 for Zn. Mn, Fe, Cu, Sb, and Sn were detectable in most samples. Cd was detected in 0.0, 30.4, and 55.1% of the dispenser, aerosol, and tank samples respectively. Arsenic was detected in 10.7% of dispenser samples (median 26.7μg/kg) and these concentrations were similar in aerosol and tank samples. Aerosol mass concentrations (mg/m) for the detected metals spanned several orders of magnitude and exceeded current health-based limits in close to 50% or more of the samples for Cr, Mn, Ni, and Pb.
CONCLUSIONS
Our findings indicate that e-cigarettes are a potential source of exposure to toxic metals (Cr, Ni, and Pb), and to metals that are toxic when inhaled (Mn and Zn). Markedly higher concentrations in the aerosol and tank samples versus the dispenser demonstrate that coil contact induced e-liquid contamination. https://doi.org/10.1289/EHP2175.
Topics: Aerosols; Electronic Nicotine Delivery Systems; Metals; Metals, Heavy
PubMed: 29467105
DOI: 10.1289/EHP2175 -
Environment International Mar 2023The Medium Resolution Spectral Imager-II (MERSI-II) onboard the recently launched Chinese Fengyun-3D (FY-3D) satellite has great capability in detecting global aerosols...
The Medium Resolution Spectral Imager-II (MERSI-II) onboard the recently launched Chinese Fengyun-3D (FY-3D) satellite has great capability in detecting global aerosols as it includes aerosol bands similar to Moderate Resolution Imaging Spectroradiometer (MODIS). However, to date, aerosol retrieval based on MERSI-II is still limited to dark target regions and there is no official aerosol products for the MERSI-II. This study focuses on developing a high-precision algorithm to retrieve aerosol optical depth (AOD) suitable for entire land areas (except snow/ice and inland waters) based on MERSI-II measurements. Considering both the accuracy and retrieval efficiency, a new cost function is constructed based on (1) the fact that the AOD (550 nm) retrieved independently from different bands should be the same with the correct aerosol model, and (2) the assumption that the aerosol types are the same in the 5 × 5 km spatial range. The retrieval method based on the new cost function is nearly 50 times faster than most current methods using iterative calculations. To extend the application adaption of the FY-3D MERSI-II AOD retrieval and avoid the errors caused by the surface Lambertian hypothesis, a bidirectional reflectance distribution function (BRDF) database is built using MODIS products. Eight candidate aerosol models in different natural zones of China are constructed based on AERONET aerosol products from 2010 - 2021. The new method is applied to MERSI-II images over China and validated against ground-based measurements at 14 stations from 2020 to 2021. MODIS aerosol products from three operational algorithms are also used for comparison purposes. The results show that MERSI-II AOD retrievals agree well with the ground-based measurements with correlation coefficient (R), root mean square error (RMSE), and relative mean bias (RMB) of 0.913, 0.123, and 0.955, respectively. In addition, 72.19 % of AOD matchups fall within the expected error (EE) envelopes. The MERSI-II retrievals show higher accuracy than that of MODIS dark target (DT) and deep blue (DB) products and comparable accuracy of the MODIS Multi-Angle Implementation of Atmospheric Correction (MAIAC) product. MERSI-II AOD also shows higher stability in terms of spatial and temporal and better performance under heavy aerosol loading conditions than MODIS products. A good AOD agreement with R from 0.777 to 0.863 between MERSI-II and MODIS products is found over the land of China. The new method showing high retrieval efficiency and accuracy has great potential to be operationally applied on AOD retrieval for MERSI-II.
Topics: Air Pollutants; Particulate Matter; Environmental Monitoring; Aerosols; Algorithms
PubMed: 36842385
DOI: 10.1016/j.envint.2023.107841