Classification of aerosol-generating procedures: a rapid systematic review.

In the context of covid-19, aerosol generating procedures have been highlighted as requiring a higher grade of personal protective equipment. We investigated how official guidance documents and academic publications have classified procedures in terms of whether or not they are aerosol-generating. We performed a rapid systematic review using preferred reporting items for systematic reviews and meta-analyses standards. Guidelines, policy documents and academic papers published in english or french offering guidance on aerosol-generating procedures were eligible. We systematically searched two medical databases (medline, cochrane central) and one public search engine (google) in march and april 2020. Data on how each procedure was classified by each source were extracted. We determined the level of agreement across different guidelines for each procedure group, in terms of its classification as aerosol generating, possibly aerosol-generating, or nonaerosol-generating. 128 documents met our inclusion criteria; they contained 1248 mentions of procedures that we categorised into 39 procedure groups. Procedures classified as aerosol-generating or possibly aerosol-generating by ≥90% of documents included autopsy, surgery/postmortem procedures with high-speed devices, intubation and extubation procedures, bronchoscopy, sputum induction, manual ventilation, airway suctioning, cardiopulmonary resuscitation, tracheostomy and tracheostomy procedures, non-invasive ventilation, high-flow oxygen therapy, breaking closed ventilation systems, nebulised or aerosol therapy, and high frequency oscillatory ventilation. Disagreements existed between sources on some procedure groups, including oral and dental procedures, upper gastrointestinal endoscopy, thoracic surgery and procedures, and nasopharyngeal and oropharyngeal swabbing. There is sufficient evidence of agreement across different international guidelines to classify certain procedure groups as aerosol generating. However, some clinically relevant procedures received surprisingly little mention in our source documents. To reduce dissent on the remainder, we recommend that (a) clinicians define procedures more clearly and specifically, breaking them down into their constituent components where possible; (b) researchers undertake further studies of aerosolisation during these procedures; and (c) guideline-making and policy-making bodies address a wider range of procedures.

Fungal aerosols at dairy farms using molecular and culture techniques.

Occupational exposure to harmful bioaerosols in industrial environments is a real threat to the workers. In particular, dairy-farm workers are exposed to high levels of fungal bioaerosols on a daily basis. Associating bioaerosol exposure and health problems is challenging and adequate exposure monitoring is a top priority for aerosol scientists. Using only culture-based tools does not express the overall microbial diversity and underestimate the large spectrum of microbes in bioaerosols and therefore the extended fungal profile that farmers are exposed to. The aim of this study was to provide an in-depth characterization of fungal exposure at Eastern Canadian dairy farms using qPCR and high-throughput sequencing methods. Specific primers were used for the quantification of Penicillium/Aspergillus and Aspergillus fumigatus in dairy farms air samples. Illumina Miseq sequencing of the ITS1 region provided sequences for the diversity analyses. The minimum and maximum concentration of Penicillium/Aspergillus ranged from 4.6 × 106 to 9.4 × 106 gene copies/m3 and from 1 × 104 gene copies/m3 to 4.8 × 105 gene copies/m3 for Aspergillus fumigatus, respectively. Differences in the diversity profiles of the five dairy farms support the idea that the novel approach identifies a large number of fungal taxa. The most striking differences include Microascus, Piptoporus, Parastagonospora, Dissoconium, Microdochium, Tubilicrinis, Ganoderma, Ustilago, Phlebia and Wickerhamomyces. The presence of a diverse portrait of fungi in air may represent a health risk for workers who are exposed on a daily basis. The broad spectrum of fungi detected in this study includes many known pathogens like Aspergillus, Acremonium, Alternaria and Fusarium. Adequate monitoring of bioaerosol exposure is necessary to evaluate and minimize risks.

Detecting Lung Diseases from Exhaled Aerosols: Non-Invasive Lung Diagnosis Using Fractal Analysis and SVM Classification.

BACKGROUND: Each lung structure exhales a unique pattern of aerosols, which can be used to detect and monitor lung diseases non-invasively. The challenges are accurately interpreting the exhaled aerosol fingerprints and quantitatively correlating them to the lung diseases. OBJECTIVE AND METHODS: In this study, we presented a paradigm of an exhaled aerosol test that addresses the above two challenges and is promising to detect the site and severity of lung diseases. This paradigm consists of two steps: image feature extraction using sub-regional fractal analysis and data classification using a support vector machine (SVM). Numerical experiments were conducted to evaluate the feasibility of the breath test in four asthmatic lung models. A high-fidelity image-CFD approach was employed to compute the exhaled aerosol patterns under different disease conditions. FINDINGS: By employing the 10-fold cross-validation method, we achieved 100% classification accuracy among four asthmatic models using an ideal 108-sample dataset and 99.1% accuracy using a more realistic 324-sample dataset. The fractal-SVM classifier has been shown to be robust, highly sensitive to structural variations, and inherently suitable for investigating aerosol-disease correlations. CONCLUSION: For the first time, this study quantitatively linked the exhaled aerosol patterns with their underlying diseases and set the stage for the development of a computer-aided diagnostic system for non-invasive detection of obstructive respiratory diseases.

Assessment of primary and secondary ambient particle trends using satellite aerosol optical depth and ground speciation data in the New England region, United States.

The effectiveness of air pollution emission control policies can be evaluated by examining ambient pollutant concentration trends that are observed at a large number of ground monitoring sites over time. In this paper, we used ground monitoring measurements in conjunction with satellite aerosol optical depth (AOD) data to investigate fine particulate matter (PM2.5; particulate matter with aerodynamic diameter ≤ 2.5 µm) trends and their spatial patterns over a large U.S. region, New England, during 2000-2008. We examined the trends in rural and urban areas to get a better insight about the trends of regional and local source emissions. Decreases in PM2.5 concentrations (µg/m(3)) were more pronounced in urban areas than in rural ones. In addition, the highest and lowest PM2.5 decreases (µg/m(3)) were observed for winter and summer, respectively. Together, these findings suggest that primary particle concentrations decreased more relative to secondary ones. This is also supported by the analysis of the speciation data which showed that downward trends of primary pollutants including black carbon were stronger than those of secondary pollutants including sulfate. Furthermore, this study found that ambient primary pollutants decreased at the same rate as their respective source emissions. This was not the case for secondary pollutants which decreased at a slower rate than that of their precursor emissions. This indicates that concentrations of secondary pollutants depend not only on the primary emissions but also on the availability of atmospheric oxidants which might not change during the study period. This novel approach of investigating spatially varying concentration trends, in combination with ground PM2.5 species trends, can be of substantial regulatory importance.

On the classification and sub-classification of aerosol key types over south central peninsular India: MODIS-OMI algorithm.

Long-term (8 years), simultaneous data on aerosol optical properties from MODIS and OMI satellite sensors are analyzed to study their temporal characteristics and to infer on the major aerosol types present over the study location, Bangalore situated in south central peninsular India. Investigations are carried out on Aerosol Optical Depths (AODs), Angstrom exponent (α) and Aerosol Index (AI) for the purpose. Aerosol parameters exhibited significant seasonal variations: AODs peaking during monsoon, α during post-monsoon and AI during summer. Seasonal air mass back trajectories are computed to infer on the transport component over the study region. By assigning proper thresholds (depending on the nature of the location and transport pathways) on AOD and α values, aerosols are discriminated into their major types viz., marine influenced, desert dust, urban/industrialized and mixed types. Further sub-categorization of the aerosols has been done on an annual scale taking into account of their absorptance information in terms of the OMI-AI values. Mixed type aerosols contributed the most during all the seasons. Next to mixed type aerosols, marine influenced aerosols dominated during winter, desert dust during monsoon and summer, urban/industrialized aerosols during post-monsoon. Considering the urban nature of the study location, urban/industrialized/carbonaceous type aerosols have been significantly underestimated in these methodologies. Finally, discussion has been made on the consistency of the results obtained from the methodologies (i) based on AODs and α; (ii) based on AODs, α and AI.

Kendrick-analogous network visualisation of ion cyclotron resonance Fourier transform mass spectra: improved options for the assignment of elemental compositions and the classification of organic molecular complexity.

Here, we propose a novel computational and visual approach for the analysis of high field Fourier transform ion cyclotron resonance mass spectra (FTICR/MS) based on successive and multiple atomic and Kendrick analogous mass difference analyses. Compositional networks based on elemental compositions and functional networks based on selected functional groups equivalents enable improved assignment options of elemental composition and classification of organic complexity with tunable validation windows. The approach is demonstrated through the analysis of a 12T FTICR mass spectrum of an intricate water soluble extract of a secondary organic aerosol with a previously established abundance in CHNOS molecules.

Bacterial diversity characterization of bioaerosols from cage-housed and floor-housed poultry operations.

BACKGROUND: Although bioaerosols from both cage-housed (CH) and floor-housed (FH) poultry operations are highly concentrated, workers from CH operations have reported a greater prevalence of respiratory symptoms. OBJECTIVE: The objective of this study was to directly compare bacteria, both quantitatively and qualitatively, in bioaerosols from CH and FH poultry facilities. METHODS: Bioaerosols were collected from fifteen CH and fifteen FH poultry operations, using stationary area samplers as well as personal sampling devices. Dust, endotoxin and bacteria were quantified and bacterial diversity was investigated using PCR followed by denaturing gradient gel electrophoresis (DGGE). RESULTS: Dust (p<0.001), endotoxin (p<0.05) and bacteria (p<0.05) were significantly higher in personal bioaerosols of FH poultry operations than CH bioaerosols. Although dust and endotoxin did not differ significantly between area and personal samples within each barn type, clustering analysis of DGGE profiles of bacteria revealed that area and personal samples shared less than 10% similarity. These data suggest that area samples are not representative of personal bacteria exposures, which may be affected by worker movement, bacteria carried on the worker and worker location. Personal DGGE profiles from CH and FH operations shared less than 20% similarity and composite analysis showed that bacteria were more prevalent in personal samples from CH bioaerosols than FH bioaerosols. CONCLUSIONS: Bacteria concentration and diversity are significantly different between bioaerosols from CH and FH poultry operations.

Source identification of ambient aerosols over an urban region in western India.

A first-of-its-kind source apportionment study of the Ahmedabad, India aerosol was conducted in order to determine the major sources contributing to the measured total suspended particles (TSPs). TSP samples were collected approximately once every ten days between May 2000 and January 2003, and analyzed for TSP mass, anions, cations, and elemental concentrations. An advanced factor analysis technique, positive matrix factorization (PMF) was applied to the measured concentrations and six factors were resolved. The model resolved factors included airborne regional dust, calcium carbonate rich dust, biomass burning/vehicular emissions, secondary nitrate/sulfate, marine aerosol, and smelter. Among the resolved factors, airborne regional dust was the highest contributor to the measured TSP mass followed by calcium carbonate rich dust with their average contributions accounting for 57.9 and 19.0%, respectively. Thus, crustal factors were the most dominant sources of TSP in Ahmedabad accounting for nearly 77% of the mass. Potential source contribution function (PSCF) analysis identified parts of Madhya Pradesh and Uttar Pradesh, regions in southwestern Pakistan along the Indo-Gangetic Plain (IGP), and southern Iran as potential source locations for the airborne regional dust factor. In contrast, Rajasthan and Madhya Pradesh, and parts of northern Pakistan were identified as potential source locations for the calcium carbonate rich dust factor. It is hypothesized that aerosol contributions from several limestone quarries in Rajasthan and Madhya Pradesh may have resulted in this factor being calcium carbonate enriched.

Characterization of selected organic compound classes in secondary organic aerosol from biogenic VOCs by HPLC/MSn.

The formation of secondary organic aerosols (SOA) has been investigated intensively during the last two decades in numerous field and laboratory studies and a general understanding exists about the major particle-phase products. However, recent studies show that several new product classes, such as esters, peroxides or organosulfates, also have to be considered in order to understand the detailed chemical mechanisms leading to SOA as well as to predict the aerosol mass loadings. For the identification and quantification of these three compound classes as well as for carboxylic SOA compounds, liquid chromatography (LC)/mass spectrometry (MS) is the most appropriate analytical method. In this article we try to summarize briefly the work that has been done for the determination of SOA-related carboxylic acids and we present new LC/tandem MS results on the characterization of esters, peroxides and organosulfates. In contrast to earlier work, the mass-spectrometric characterization of the individual compounds is always based on the comparison with authentic reference compounds.

Aerosols and splatter in dentistry--a neglected menace?

Two main types of particulate matter may be produced during routine dental procedures, namely aerosols and splatter. The principal difference between them is the size of the particles from which they are made. The behaviour of such particles in air and their possible health risks are complex. However, the use of high volume evacuation, pre-procedural mouthrinses and rubber dam are the most effective methods of reducing the unwanted risk of exposure.

Health-related aerosol measurement: a review of existing sampling criteria and proposals for new ones.

Interest in particle size-selective sampling for aerosols in working and ambient living environments began in the early 1900s when it became apparent that the penetration into-and deposition in-the respiratory tract of aerosol-exposed humans of inhaled particles was dependent on particle size. Coarse particles tended to be filtered out during inhalation and in the upper parts of the respiratory tract, so only progressively smaller particles penetrated down to the deep regions of the lung. Over time, following experimental studies with 'breathing' mannequins in wind tunnels and with human volunteer subjects in the laboratory, a clear picture has emerged of the physical, physiological and anatomical factors that control the extent to which particles may or may not reach certain parts of the respiratory tract. Such understanding has increasingly been the subject of discussions about aerosol standards, in particular the criteria by which exposure might be defined in relation to given classes of aerosol-related health effect-and in to turn aerosol monitoring. The ultimate goal has been to develop a set of criteria by which exposure standards are scientifically relevant to the health effects in question. This paper reviews the scientific basis for such criteria. It discusses the criteria that have already been widely discussed and so are either being applied or are on the threshold of practical application in standards. It also discusses how new advanced knowledge may allow us to extend the list of particle size-selective criteria to fractions that have not yet been widely discussed but which may be of importance in the future.

Epidemiology of volatile substance abuse (VSA) cases reported to US poison centers.

Volatile substance abuse (VSA) is believed to be widespread. The Toxic Exposure Surveillance System (TESS) of the American Association of Poison Control Systems offers an opportunity to evaluate the epidemiology of volatile substance abuse using a data set that captures data from a large geographic area covering a wide-ranging group of socioeconomic strata, ethnic groups, and demographics. To utilize this potential we analyzed a data set of TESS for the 6-year period of 1996 through 2001 involving all cases of intentional inhalational abuse of nonpharmaceutical substances. Over the study period there was a mean annual decline of 9% of reported VSA with an overall decline of 37% from 1996 to 2001. Volatile substance abuse was reported primarily in children, with 6358 cases (54%) in children 13-19 yr and 1803 (15%) cases in children 6-12 yr. Fifty-two cases were reported in children < 5 or = 5 yr. A total of 2330 (20%) VSA cases had a serious outcome, defined as either moderate effect (n = 2000), major effect (n = 267), or death (n = 63). The top five categories of substances abused were gasoline (41%), paint (13%), propane/butane (6%), air fresheners (6%), and formalin (5%). Three categories were responsible for the majority of deaths: gasoline (45%), air fresheners (26%), and propane/butane (11%). While there was a decline in reported cases, there was no decline in major outcomes or fatalities. Volatile substance abuse was reported in all 50 states, with case distribution similar to population distribution. However, seven states had > 2 times the expected rate based on their population; three western states, two midwestern states, and two Appalachian states. The role of urban vs. rural population may possibly explain the difference in numbers, with a greater incidence of VSA cases reported in states with large rural populations. The mean monthly occurrence rate was 162 VSA cases/month (S.D. +/- 10.85). There were 4 months that were > 2 standard deviations from the mean, with two peak months (May, 192/month and March, 187/month) and two trough months (December, 126/month and January, 137/month). This report presents a broad picture of VSA in the United States. Volatile substance abuse, as reported to U.S. poison centers, appears to be on the decline, but continues to be an ongoing problem. Volatile substance abuse is reported throughout the U.S. in all areas of the country, with a higher incidence in states with large rural populations. A small group of substances appears responsible for the majority of deaths. It is imperative that we continue to educate the public and healthcare professionals regarding the risks of VSA and hopefully impact the incidence of VSA.

A personal particle speciation sampler.

Fuller understanding of personal exposures to particulate matter with aerodynamic diameters below 2.5 microm (PM2.5*) requires a personal sampler suitable for assaying not only PM2.5 mass but also its major chemical constituents: elemental carbon, organic carbon, sulfates, and nitrates. The goal to measure these constituents simultaneously imposes several constraints on personal sampler design. The aim of this project was to develop a sampler within these constraints that would be suitable for personal monitoring over 8 hours. In addition, with the intent to improve the precision of mass measurements, we investigated offline use of beta attenuation. The personal particle speciation sampler (PPSS) includes an inlet to remove particles larger than 2.5 microm, 2 sampling channels, and a pump with flow control. One channel serves for measuring particle mass and inorganic ions; the other, for measuring organic carbon and elemental carbon. Denuders can be placed in either channel or both channels. A backup filter can be placed on the denuded channel to collect volatilized particulate nitrate. Two prototype PPSS units were built and tested. The results of both laboratory testing of key PPSS components and a limited field study of the prototype in comparison to an AIHL (Air and Industrial Hygiene Laboratory) cyclone-based sampler are reported.

Conceptos y actualidades sobre el uso de la aerosolterapia en pediatría / Concepts and state of the art about the use of aerosols therapy in pediatrics

En los últimos años hemos observado dos hechos singulares: un acelerado aumento de los cuadros asmáticos y bronquiales obstructivos en general en la población infantil y por otra parte el advenimiento de diversas modalidades terapéuticas para la administración de los broncodilatadores. De allí la importancia de actualizar nuestros conceptos sobre la aerosolterapia en pediatría. Revisamos las condiciones físicas que los aerosoles deben tener para lograr un efecto terapéutico, los factores clínicos que pueden modífícar tanto la penetración como el depósito de las partículas, y los tipos de aparatos usados en la aerosolterapía: nebulizadores, inhaladores de dosís medida (MDI) y los inhaladores de polvo seco. Se dan algunas pautas para la correcta administración de los nebulizadores y los MDI, señalando las ventajas y desventajas de cada uno de ellos. Por último se enfatiza la superioridad de los MDI más aerocámara con mascarilla facial, para la inmensa mayoría de niños con obstrucción bronquial

Aerossóis fibrogênicos e näo fibrogênicos / Fibrogenic and non-fibrogenic aerosols

A atual ediçäo da Norma regulamentadora 7 (NR7) traz conceitos novos em relaçäo à vigilância epidemiológica e controle médico de trabalhadores expostos a poeiras minerais e orgânicas. O potencial fibrogênico de determinado aerosol deve ser analisado no momento de delinear-se a periodicidade do controle radiológico. Neste trabalho, discutimos o conceito de fibrogenicidade de determinado aerosol, quais säo os critérios de análise de diferentes situaçöes e as limitaçöes desses procedimentos. O objetivo é trazer à tona os elementos relevantes para o julgamento de situaçöes individuais que levem ao estabelecimento de pontos que comporäo um programa de controle de riscos respiratórios de trabalhadores expostos a poeiras minerais.

Effect of solution and suspension type aerosol of formoterol on tremor response and airways in patients with asthma.

BACKGROUND: Aerosol delivery and deposition to the oropharynx and the lungs have been found to be different for solution-type and suspension-type metered-dose aerosols used for treatment of asthma. We investigated possible differences in clinical effects between solution and suspension metered-dose formoterol aerosols. METHODS: A total of 24 patients with asthma (forced expiratory volume in 1 second, < or = 70% predicted) inhaled single doses (12 micrograms or 24 micrograms) of formoterol solution and suspension so that we could investigate the immediate tremor, airway, and cardiovascular responses in a randomized, double-blind, crossover trial. Fenoterol suspension aerosol (400 micrograms) was used for comparison (single-blind, poststudy, nonrandomized administration). Fenoterol (400 micrograms) as a rescue medication was inhaled after 120 minutes on each of the 5 study days. RESULTS: The order of mean (+/- SEM) maximum tremor acceleration was as follows: 12 micrograms formoterol solution (67.92 +/- 4.54 cm x sec-2) < 24 micrograms solution (73.46 +/- 4.51 cm x sec-2) < 12 micrograms suspension (80.87 +/- 5.08 cm x sec-2) < fenoterol (84.13 +/- 4.21 cm x sec-2) < 24 micrograms formoterol suspension 88.54 +/- 6.26 cm x sec-2). Maximum increase in specific airway conductance ranged from 0.48 +/ 0.03 to 0.55 +/- 0.04 sec-1 x kPa-1 for all drugs (p > 0.05). No change in cardiovascular parameters occurred (p > 0.05). CONCLUSION: No difference in the bronchial response to either formulation of formoterol was found. Tremor response to suspension aerosol (24 micrograms > 12 micrograms) was higher than that to solution aerosol (24 micrograms > 12 micrograms), indicating possible differences in systemic absorption because of a different deposition pattern. Rescue medication demonstrated systemic effects on tremor that were additive to those of formoterol.