Respiratory Health Hazards Research Articles

Microbial Community Establishment, Succession, and Temporal Dynamics in an Industrial Semi-Synthetic Metalworking Fluid Operation: A 50-Week Real-Time Tracking.

Microorganisms colonizing modern water-based metalworking fluids (MWFs) have been implicated in various occupational respiratory health hazards to machinists. An understanding of the exposure risks from specific microbial groups/genera/species (pathogenic or allergenic) and their endotoxins and the need for strategies for effective, timely fluid management warrant real-time extended tracking of the establishment of microbial diversity and the prevailing fluid-related factors. In the current study, the microbial community composition, succession, and dynamics of a freshly recharged industrial semi-synthetic MWF operation was tracked in real-time over a period of 50 weeks, using a combination of microbiological and molecular approaches. Substantial initial bacterial count (both viable and non-viable) even in the freshly recharged MWF pointed to the inefficiency of the dumping, cleaning, and recharge (DCR) process. Subsequent temporal analysis using optimized targeted genus/group-specific qPCR confirmed the presence of Pseudomonads, Enterics, Legionellae, Mycobacteria (M. immunogenum), Actinomycetes, and Fungi. In contrast, selective culturing using commercial culture media yielded non-specific isolates and collectively revealed Gram-negative (13 genera representing 19 isolates) and Gram-positive (2 genera representing 6 isolates) bacteria and fungi but not mycobacteria. Citrobacter sp. and Bacillus cereus represented the most frequent Gram-negative and Gram-positive isolates, respectively, across different media and Nectria haematococca isolation as the first evidence of this fungal pathogen colonizing semi-synthetic MWF. Unbiased PCR-DGGE analysis revealed a more diverse whole community composition revealing 22 bacterial phylotypes and their succession. Surges in the endotoxin level coincided with the spikes in Gram-negative bacterial population and biocide additions. Taken together, the results showed that semi-synthetic MWF is conducive for the growth of a highly diverse microbial community including potential bacterial and fungal pathogens, the current DCR practices are inefficient in combating microbial reestablishment, and the practice of periodic biocide additions facilitates the build-up of endotoxins and non-viable bacterial population.

A numerical study on sedimentation effect of dust, smoke and traffic particle deposition in a realistic human lung

Inhalation of pollutants can be deadly for respiratory health, as toxic pollutants can penetrate the deep lungs which could occur severe respiratory infection and lead to life-threatening respiratory diseases. The excessive presence of pollutants in the environment increases the concern of potential respiratory health hazards. To date, a microscopic understanding of the sedimentation effect on dust, smoke and traffic (pollutant) particles transported to the airways is missing in the literature. This first-ever study aims to analyse the sedimentation effect in various directions of pollutant particle transport in airways. This study also quantitatively explains how particle size, density, and physical exercise impact pollutant particle transport and deposition (TD) in the human lung airways. The contribution of the sedimentation effect is largely independent of particle size. The sedimentation effect can also be found significant at the trachea region when the fluid flow is horizontal. Overall, traffic particles with large diameters and high flow rates are deposited in the upper lung, whereas dust particles with large diameters and high flow rates are deposited in the deep lung. It is expected that 79.1 % of the particles will reach the deep lung. The difference between the deposition rates of the horizontal and vertical lungs reduces if the particle size reduces, the flow rate increases or the particle density reduces. The deposition rate of a horizontal lung for the heaviest particles (traffic) at 15 L/min flow rate is about 4.5 % higher than that of a vertical lung with the same flow rate.

Work-related respiratory health conditions among construction workers: a systematic narrative review

BackgroundEmerging evidence in both developed and developing countries indicate that occupational health hazards and diseases among construction workers constitute a significant public health challenge. While occupational health hazards and conditions...

Associations among Historical Neighborhood Disinvestment, Hazardous Air Pollutants, and Current Adult Asthma Prevalence

Associations among Historical Neighborhood Disinvestment, Hazardous Air Pollutants, and Current Adult Asthma Prevalence

Spatial Distribution and Physicochemical Properties of Respirable Volcanic Ash From the 16-17 August 2006 Tungurahua Eruption (Ecuador), and Alveolar Epithelium Response In-Vitro.

Tungurahua volcano (Ecuador) intermittently emitted ash between 1999 and 2016, enduringly affecting the surrounding rural area and its population, but its health impact remains poorly documented. We aim to assess the respiratory health hazard posed by the 16-17 August 2006 most intense eruptive phase of Tungurahua. We mapped the spatial distribution of the health-relevant ash size fractions produced by the eruption in the area impacted by ash fallout. We quantified the mineralogy, composition, surface texture, and morphology of a respirable ash sample isolated by aerodynamic separation. We then assessed the cytotoxicity and pro-inflammatory potential of this respirable ash toward lung tissues in-vitro using A549 alveolar epithelial cells, by electron microscopy and biochemical assays. The eruption produced a high amount of inhalable and respirable ash (12.0-0.04kg/m2 of sub-10μm and 5.3-0.02kg/m2 of sub-4μm ash deposited). Their abundance and proportion vary greatly across the deposit within the first 20km from the volcano. The respirable ash is characteristic of an andesitic magma and no crystalline silica is detected. Morphological features and surface textures are complex and highly variable, with few fibers observed. In-vitro experiments show that respirable volcanic ash is internalized by A549 cells and processed in the endosomal pathway, causing little cell damage, but resulting in changes in cell morphology and membrane texture. The ash triggers a weak pro-inflammatory response. These data provide the first understanding of the respirable ash hazard near Tungurahua and the extent to which it varies spatially in a fallout deposit.

A Computational Approach for Respiratory Hazard Identification of Flavor Chemicals in Tobacco Products.

Flavor chemicals contribute to the appeal and toxicity of tobacco products, including electronic nicotine delivery systems (ENDS). The assortment of flavor chemicals available for use in tobacco products is extensive. In this study, a chemistry-driven computational approach was used to evaluate flavor chemicals based on intrinsic hazardous structures and reactivity of chemicals. A large library of 3012 unique flavor chemicals was compiled from publicly available information. Next, information was computed and collated based on their (1) physicochemical properties, (2) global harmonization system (GHS) health hazard classification, (3) structural alerts linked to the chemical's reactivity, instability, or toxicity, and (4) common substructure shared with FDA's harmful and potentially harmful constituents (HPHCs) flavor chemicals that are respiratory toxicants. Computational analysis of the constructed flavor library flagged 638 chemicals with GHS classified respiratory health hazards, 1079 chemicals with at least one structural alert, and 2297 chemicals with substructural similarity to FDA's established and proposed list of HPHCs. A subsequent analysis was performed on a subset of 173 chemicals in the flavor library that are respiratory health hazards, contain structural alerts as well as flavor HPHC substructures. Four general toxicophore structures with an increased potential for respiratory toxicity were then identified. In summary, computational methods are efficient tools for hazard identification and understanding structure-toxicity relationship. With appropriate context of use and interpretation, in silico methods may provide scientific evidence to support toxicological evaluations of chemicals in or emitted from tobacco products.

Respiratory health hazards in agriculture - assessment by job exposure matrices

Respiratory health hazards in agriculture - assessment by job exposure matrices

Perception of Firefighters on Risk of Exposure to Respiratory Health Hazard: A Qualitative Analysis in Malaysia

Firefighters are exposed to multiple occupational hazards, where one of the hazards is chemical hazard that can affect the respiratory system. However, little is known regarding the perception of firefighters on the source of exposure to respiratory hazards, particularly in Malaysia. This work aims to explore the firefighter’s perspective on respiratory hazard exposure and to examine the compliance of the use of personal protective equipment (PPE). In-depth interviews were employed among 12 firefighters at Fire and Rescue Department of Malaysia in September 2020. The interview recordings were transcribed verbatim and of thematic analysis done via the NVIVO 12 programme. All participants were Malay, male, and married. The respiratory hazard exposure perceived can be divided into occupational source (e.g. exposure to smoke from firefighting, fire training, firefight demonstration, commuting, firefight vehicles: chemicals and dust) and non-occupational source (e.g. smoking). Firefighter recognised both the importance of wearing PPE and the fact they are still not compliant in wearing it. They also perceived wearing PPE as burden and having only a limited stock of PPE. Education and training need to be reinforced to strengthen firefighters’ risk perception, hazard identification, and risk assessment of hazards exposure. Strict standard operating procedure (SOP) and supervision during firefighters’ task is crucial to reduce hazard exposure and increase PPE compliance. Systematic and thorough inventory management is needed to ensure adequate PPE supply. Post qualitative analysis, the firefighters’ perception on respiratory hazard exposure was obtained, demonstrating that the analysis is ready for further study.

A study of health profile and effects of ambient air pollution among auto drivers of Bangalore city

Background: Auto drivers battle several occupational health hazards due to increasing pollution and unhealthy lifestyle. Improper diet and sleeping habits coupled with smoking, tobacco and alcohol use make them prone to respiratory and cardiovascular health hazards. Objectives: To assess the health status and quality of life (QoL) among auto drivers in Bangalore city and to study the association of selected parameters with respiratory and cardiac morbidities. Methods: In this cross-sectional study, 450 auto drivers were given a questionnaire and they were distributed according to age, education, body mass index, smoking, tobacco and/or alcohol consumption. The QoL was assessed by World Health Organization Quality of Life Instrument (WHOQOL-BREF) and peak expiratory flow, blood pressure, and blood sugar levels for each participant were recorded. The association between two categorical variables was determined by Chi-square test and p?0.05 was considered statistically significant. Results: The association of number of years of driving with prevalence of chronic morbidity (p=0.005), hypertension (p=0.008), diabetes (p<0.001), and heart disease (p=0.04) were significant. QoL for physical and environmental domain were 16.11±0.28 and 12.48±0.06, respectively. Conclusion: A proportional increase in the risk of respiratory and cardiac morbidities with increasing number of driving years was observed among auto drivers.

Discard Plastic Burning: A Serious Risk Factor in Dehradun, India

Background: Dehradun, India is going to most exceedingly influencing and breaking down air quality due to the burning of the discarded plastic, where the natural beauty is the prized component. Carelessly threw the disposed of plastic and burning affecting the environment and people’s health drastically. Consequently, various sicknesses and disease are the common phenomenon. Thus, this region urgently required an extensive evaluation by the governmental and non-governmental organization to solve this issue and make a strict control to stop the plastic on every day utilize premise. Their people groups endure much because of their own activity. Objectives: Current study report about the environmental and public health concern due to the discard plastic burning on daily basis which causes severe respiratory disease and health hazards. Methods: The current study focused on the observation and collection of plastic burning activities done by the people of on daily basis in the last three year from August 2017 to July 2020. Results: As regularly as conceivable it can be found in every 20 houses there are cluster plastics burning on daily basis. Burnt Plastic, releasing lethal gases into the environment which include substances like dioxins, furans, mercury and polychlorinated biphenyls which is a hazardous compound and conceivably hurting to all kind of life. Dehradun, India is emerging as a hotspot for the broken air quality especially due to burning of discard plastic in this region and introducing smoke into the atmosphere. Due to this, numbers of affected people are increasing an everyday basis. This broken air quality is also responsible for greenhouse gases (GHG) and increasing global warming potential. Conclusions: Finally, I might want to focus this area move toward becoming a hotspot to look with crumbled air quality from the last couple of years. Numbers of multiple illnesses affected peoples increasing year by year. The level of dangerous compound increasing in the atmosphere, in this way it is needful to take preparatory measure to make strict regulation and develop treatment facility to save Dehradun. As this region is like a gift by nature.

Environmental impact assessment of cement industries using mathematical matrix method: case of Ghayen cement, South Khorasan, Iran.

Cement industries produce millions of tons of by-products each year, including dust, toxic gases, and heavy metals, which pose respiratory health hazards and environmental pollution. Although several literatures have investigated environmental impact in cement factories, the extent to which these assessments affect the population has received limited responsiveness. This study investigates this gap by examining the environmental impacts of the Ghayen Cement Industry on environmental components and public health. Using a mathematical matrix, it found that the effect of the cement factory on the environment produced four categories of significant effects: L, low; M, medium; H, high; and VH, very high. Results in terms of basic criteria revealed 0.70 of the most destructive effect was related to water pollution. Regarding the interaction effect of project activities (basic and complimentary basic criteria) on environmental components, the highest destructive effect was excavation and land deformation while the lowest effect was on public health. The study also found out that the use of compensation factors reduced the negative effect of the project on the environment. The use of common methods of environmental improvement such as erosion control, proper location of facilities, and the creation of green spaces is essential to mitigate the impact of projects on the environment.

Selection of operational parameters for a smart spraying system to control airborne PM10 and PM2.5 dusts in underground coal mines

Airborne dust in underground hard coal mines is an ongoing explosion and respiratory health hazard. The latest design solution for controlling dusts, the smart spraying system, is described. From the results of stand tests, the main factors determining the efficiency of the new device are: 1) the integrated real-time acquisition of dust particle size and concentration data, determined using a new optical dust meter; 2) the fractional distribution of water droplets; and 3) the selection of droplet size to capture PM10 and PM2.5. The latter two factors are automatically controlled, based on dust measurements, by varying the pressure of water and compressed air supplied to the sprayer nozzles. The effects of varying these parameters and the results of stand tests are presented. The spraying device was tested for the effectiveness of PM2.5 dust and PM10 dust reduction in underground conditions in the KWK Pniówek mine. The tests were based on the following Polish Standards: PN-91/Z-04030/05 and PN91/Z-04030/06, which define the methodology for measurements of inhalable and respirable dust at workplaces using the filtration-weighing method to determine the concentration of inhalable and respirable dust with the spraying system on and off. The results showed that the assumed objective, i.e. development of a dust control device that would reduce PM2.5 dust (by min. 25 %) and PM10 dust (by min. 20 %) more effectively than the currently used solutions, was achieved in the project. At the same time, the device, due to application of dust sensor, continuously adjusts the parameters of spraying streams to the dust concentration level, optimizing the consumption of water and compressed air. Similar results in reduction of PM10 and PM2.5 dust, with an average effectiveness of over 60 % is the undoubted advantage of the device.

Prevalence of Chronic Bronchitis and Respiratory Health Profile of a Population Exposed to Wood Smoke in Nicaragua.

Background.Household air pollution (HAP) is one of the most important environmental risk factors worldwide associated with chronic respiratory diseases.Objectives.The present study focused on respiratory health in a population with high wood smoke exposure in Nicaragua.Methods.We employed a cross-sectional study with 213 participants. Data on the prevalence of chronic bronchitis (chronic bronchitis), chronic obstructive pulmonary disease (COPD) and asthma, including respiratory scores and pulmonary function tests, were documented. The role of risk factors for chronic bronchitis was analyzed.Results.We found a high prevalence of chronic airway diseases in the population exposed to wood smoke. A higher prevalence of chronic bronchitis was found in persons serving as primary cooks in households. Further confounding factors for chronic bronchitis included age, a prior diagnosis of asthma, inhalational allergies and lower socioeconomic status. Respiratory scores were elevated in individuals with chronic bronchitis.Conclusions.This is one of the first studies in a wood smoke-exposed population in Nicaragua showing a high prevalence of chronic bronchitis and COPD with an emphasis on the analysis of personal and environmental risk factors. Further studies are needed to address which combination of interventions is most efficient for ameliorating respiratory health hazards.Participant Consent.ObtainedEthics Approval.The study protocol was approved by the Ethics Committee of the University of Luebeck, Germany (reference number 12-214), and by the Ethics Committee of the Department of Medical Sciences at National Autonomous University of Nicaragua, Managua, Nicaragua.Competing Interests.The authors declare no competing financial interests.

Update of occupational lung disease.

ObjectiveOccupational Lung Disease is an oldest but still a biggest problem in occupational health.MethodsSteering Committee members of the Japan Society for Occupational Health (JSOH) Occupational Lung Disease Study Group selected and summarized current topics on occupational lung diseases based on expert opinion, as informed by governmental regulation, public health concerns, and frequently discussed in related academic conferences.ResultsThe topics included in this review are professional education in medical screening skills, 2014 update of Helsinki Criteria, respiratory diseases found in the earthquake and tsunami affected regions, newly recognized occupational lung diseases, and potential respiratory health hazards.DiscussionsAlthough occupational lung diseases seem to stay as one of the major concerns in occupational health, screening tools and control measures are standardized for the better prevention of the diseases. As this health problem usually occurs in where the most actively economically developing area is, the patients tend to increase in emerging economic powers with huge population.

Phase partitioning during fragmentation revealed by QEMSCAN Particle Mineralogical Analysis of volcanic ash

Volcanic ash particle properties depend upon their genetic fragmentation processes. Here, we introduce QEMSCAN Particle Mineralogical Analysis (PMA) to quantify the phase distribution in ash samples collected during activity at Santiaguito, Guatemala and assess the fragmentation mechanisms. Volcanic ash from a vulcanian explosion and from a pyroclastic density current resulting from a dome collapse were selected. The ash particles resulting from both fragmentation modes are dense and blocky, typical of open-vent dome volcanoes and have a componentry consistent with their andesitic composition. We use image analysis to compare the fraction of each phase at particle boundaries compared to the total particle fraction. Our results show that the explosion-derived ash has an even distribution of plagioclase and glass, but boundaries enriched in pyroxene and amphibole. In contrast, the ash generated during dome collapse has an increased fraction of glass and decreased fraction of plagioclase at particle boundaries, suggesting that fractures preferentially propagate through glass during abrasion and milling in pyroclastic flows. This study presents QEMSCAN PMA as a new resource to identify generation mechanisms of volcanic ash, which is pertinent to volcanology, aviation, respiratory health and environmental hazards, and highlights the need for further experimental constraints on the fragmentation mechanism fingerprint.

Respiratory Health Hazards in Women

Respiratory tract diseases are public health problems, and these diseases affect the air passages, including the nasal passages, the bronchi, and the lungs. They range from acute infections, such as pneumonia and bronchitis, to chronic conditions such as asthma and chronic obstructive pulmonary disease. The prevalence of chronic respiratory morbidity among females is significantly higher compared to the general population of the country. It is a conditions affecting the organs and tissues that make gas exchange possible and includes conditions of the upper respiratory tract, trachea, bronchi, bronchioles, alveoli, pleura and pleural cavity, the nerves, and muscles of breathing. Females had respiratory illness were also higher among the users of tobacco and alcohol. Respiratory diseases range from mild and self-limiting, such as the common cold, to life-threatening entities such as bacterial pneumonia, acute asthma, and lung cancer. When women must cope with respiratory disease in the face of significant psychological, social, or cultural challenges, such as depression, economic burdens, competing family responsibilities, or disease stigma, the risk of nonadherence may increase. Women response with drugs is a big issue, because women of child-bearing age were excluded from participating in clinical studies, and information regarding gender-dependent responses to drugs in general and to respiratory drugs specifically has been lacking.

Exposure to heavy metals alters the surface topology of alveolar macrophages and induces respiratory dysfunction among Indian metal arc-welders

Despite the available clinico-epidemiological evidence of heavy metal-associated respiratory health hazards among metal arc-welders, experimental confirmation of such an association is lacking. In this study, we recruited 15 metal arc-welders and 10 referent workers without direct exposure. We assessed respiratory health through a questionnaire and spirometry; estimated manganese, nickel and cadmium levels in blood, urine and induced sputum; performed differential counts of sputum leucocytes and measured plasma malondialdehyde (MDA). We used atomic force and scanning electron microscopy to assess the physical property of the alveolar macrophages (AMs) obtained from induced sputum and analysed cell surface deposition of heavy metals using energy dispersion X-ray analysis (EDX). Sputum cellular DNA damage was assessed by DNA-laddering assay. There was a higher body burden of manganese and nickel in the metal arc-welders than the referents. Among major spirometric indices, only the forced mid-expiratory flow rates (FEF25-75) were reduced in the welders compared with the referents (63.4 ± 14.7 vs. 89.2 ± 26.7, p < 0.01); this reduction was associated with both heavy metal levels (β: -41.8, 95% CI: -78.5% to -5.1%) and plasma MDA (-0.37; -0.68 to -0.06). In metal arc-welders, significant physical and morphological changes were observed in AMs through microscopic evaluation while EDX analyses demonstrated higher deposition of heavy metals on the AM cell surface than the referents. We also observed a higher degree of DNA damage in the sputum cells of the exposed workers than the referents. Heavy metal exposure-induced adverse respiratory effects among metal arc-welders are mediated through haematological and cytological interactions.

Driving Behaviour and Sustainable Mobility—Policies and Approaches Revisited

Climate change is receiving increasing attention in recent years. The transportation sector contributes substantially to increased fuel consumption, greenhouse gas (GHG) emissions, and poor air quality, which imposes a serious respiratory health hazard. Road transport has made a significant contribution to this effect. Consequently, many countries have attempted to mitigate climate change using various strategies. This study analysed and compared the number of policies and other approaches necessary to achieve reduced fuel consumption and carbon emission. Frequency aggregation indicates that the mitigation policies associated with driving behaviours adopted to curtail this consumption and decrease hazardous emissions, as well as a safety enhancement. Furthermore, car-sharing/carpooling was the least investigated approach to establish its influence on mitigation of climate change. Additionally, the influence of such driving behaviours as acceleration/deceleration and the compliance to speed limits on each approach was discussed. Other driving behaviours, such as gear shifting, compliance to traffic laws, choice of route, and idling and braking style, were also discussed. Likewise, the influence of aggression, anxiety, and motivation on driving behaviour of motorists was highlighted. The research determined that driving behaviours can lead to new adaptive driving behaviours and, thus, cause a significant decrease of vehicle fuel consumption and CO2 emissions.

Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples

BackgroundThe eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland’s volcanoes to Icelandic and Northern European populations.MethodsA physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network.ResultsIcelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m2 g−1, which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO•), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after ‘refreshing’ sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m−2, with mafic samples releasing more iron than silicic samples. All samples were non-reactive in a test of red blood cell-membrane damage.ConclusionsThe primary particle-specific concern is the potential for future eruptions of Iceland’s volcanoes to generate fine, respirable material and, thus, to increase ambient PM concentrations. This particularly applies to highly explosive silicic eruptions, but can also hold true for explosive basaltic eruptions or discrete events associated with basaltic fissure eruptions.

The iron-catalysed surface reactivity and health-pertinent physical characteristics of explosive volcanic ash from Mt. Etna, Italy

Mount Etna is Europe’s largest and most active volcano. In recent years, it has displayed enhanced explosive activity, causing concern amongst local inhabitants who frequently have to live with, and clean up, substantial ashfall. Basaltic volcanic ash is generally considered unlikely to be a respiratory health hazard due to its often coarse nature (with few particles sub-10 μm diameter) and lack of crystalline silica. However, a previous study by the authors showed the capability of basaltic ash to generate the hydroxyl radical, a highly-reactive species which may cause cell damage. That study investigated a single sample of Etna ash, amongst others, with data giving an early indication that the Etnean ash may be uniquely reactive.In this study, we analyse a suite of Etnean samples from recent and historical eruptions. Deposits indicate that Etna’s past history was much more explosive than current activity, with frequent sub-plinian to plinian events. Given the recent increase in explosivity of Etna, the potential hazard of similarly, or more-explosive, eruptions should be assessed.A suite of physicochemical analyses were conducted which showed recent ash, from 2001 and 2002 explosive phases, to be of similar composition to the historical deposits (trachy-basaltic) but rather coarser (< 2.4 c.v.% sub-10 μm material and <11.5 c.v.% sub-10 μm material, respectively), but the potential for post-depositional fragmentation by wind and vehicles should not be ignored. One recent sample contained a moderate number of fibre-like particles, but all other samples were typical of fine-grained ash (blocky, angular with electrostatic or chemical aggregation of finer particles on larger ones). The surface reactivity analyses (Fenton chemistry, on samples from recent eruptions only) showed that Etnean ash is more reactive in hydroxyl radical generation than other basaltic ash, and samples of intermediate composition. This high reactivity suggests that Etnean ash could promote oxidative stress in exposed cells. Therefore, further investigation of the potential toxicity, through cellular tests, is now warranted in order to provide a comprehensive health hazard assessment.