Aerosol emission from cleaning sprays - design and evaluation of a generation and a characterization system for spray aerosols and a human pre-exposure study

In Sweden, the 10th most common occupation is professional cleaning. Cleaning workers are exposed to many risk factors including high physical workload and the development of new-onset asthma and other types of respiratory symptoms. This master thesis has been a part of a research project at the division of Ergonomics and Aerosol Technology (EAT), Lund University, in which the health aspect of cleaning workers with regards to ergonomic load and airway exposure, when using spray bottles compared to traditional cleaning with cloth and bucket, is being investigated. The main objectives of this thesis have been to identify and characterize the most common spray cleaning products used by cleaning workers in Sweden, and to design a human pre-exposure study to determine dose-response relationships. The identification of cleaning products was done by a phone survey and based on the responses from this survey six products, for the use in bathrooms, on windows, on stains and for all surfaces were selected. Aerosol characterization of the products was done by two main methods, determining the airborne mass fraction and the particle/gas ratio. The airborne mass fraction was measured using a paper-setup. The cleaning product was sprayed at a paper taped on the wall and the mass of the bottle and of the paper was weighed before and after spraying, to determine how much mass that remained airborne, the airborne mass fraction. The particle/gas ratio was determined by measuring the concentration increase during product use, in turn determining the source strength for the particles. This was compared to the total source strength (for the bottle) and the source strength for the surface (obtained from the airborne mass fraction) to determine the particle/gas ratio. The two window cleaning sprays had a high airborne mass fraction (9.1 and 15.7 % respectively) compared to the sprays for stains and all surfaces (2.7 and 4.9 % respectively). However, the mass percentage of particles suspended in the air after spraying, for all products, was very low. More than 99.9 % of the initial spray droplet mass would evaporate to a gaseous phase. The mass median diameters measured with the APS (for the dried particles) were 1.8-4.2 µm for all products. The human pre-exposure study showed no statistical connections due to the limited number of subjects and the large individual variations, but some trends could be seen. For example that the tear film break up time decreased with increasing spray dose, suggesting that the tear film is destabilizing with increased exposure to a window cleaning spray. An increase in nose symptoms could also be observed with increasing spray dose.Bättre lite skit i hörnen än ett sprejstädat hem? Städsprejer används av allt fler, både hemma och på arbetsplatser. Den senaste forskningen visar dock att användning av städsprejer kan leda till akuta hälsoeffekter, både i näsa och i ögon. I Sverige är städare det tionde vanligaste yrket med mer än 70 000 anställda varav mer än 75 % är kvinnor. Städpersonal är dock utsatt för flera arbetsrelaterade riskfaktorer, däribland hög belastning på skelett och muskler och problem med luftvägarna. Som en del i ett forskningsprojekt vid Lunds universitet har en mindre exponeringsstudie nyligen genomförts. Åtta frivilliga försökspersoner exponerades för olika doser av en fönsterputssprej. Försökspersonerna fick själva putsa ett fönster i en kammare med kontrollerat luftflöde och partikelfiltrering. Hälsoeffekterna utvärderades sedan med hjälp av tre olika metoder, ett frågeformulär och två medicinska undersökningar. I formulären fick försökspersonerna själva fylla i om de kände av några besvär i näsan, ögonen eller halsen, både före, under och efter sprejningen. Den första medicinska undersökning som genomfördes var en mätning av det maximala luftflöde som försökspersonen kan uppnå genom att andas in genom näsan, en så kallad PNIF-mätning. Denna mätning gjordes både före och efter varje sprejning och gav ett mått på hur påverkad näsan blir av exponeringen. Den andra undersökningen var en mätning av hur lång tid det tar för ögonens tårfilm att börja spricka upp, en så kallad BUT-mätning. Denna gjordes före den första sprejningen och sedan efter varje sprejdos och gav ett mått på hur torra ögonen blev. Från denna studie kunde ett par trender identifieras. Exempelvis minskade BUT-tiden när spraydosen ökade, vilket innebär att tårfilmen påverkas av sprejningen och ögonen blir torrare. En annan trend som kunde ses var att försökspersonerna verkade uppleva starkare symptom i näsan i takt med att sprejdoserna ökade, en påverkan som dock inte kunde ses i PNIF-mätningarna. När städsprejerna används bildas vätskedroppar av rengöringsmedel, så kallade aerosoler, vilka sprids i luften. Som en del i projektet undersöktes även hur stor del av den vätska som sprejades ut från flaskan som faktiskt hamnade på väggen (mot vilken sprejningen gjordes) och hur stor del som förblev i luften och därmed kunde andas in. Mätningar gjordes även för att undersöka hur stora vätskedropparna var, direkt när de kommer ut från sprejmunstycket, men också hur små partiklarna blivit efter att de torkat ett par sekunder i luften. Totalt undersöktes sex olika rengöringsprodukter. Resultaten från dessa mätningar visade att mycket av fönsterputssprejerna stannade kvar i luften, mellan 9 och 16 % av det som sprejades ut från flaskan, i jämförelse med produkterna för fläckar och allmänna ytor. Av dessa förblev endast mellan 3 och 5 % i luften efter sprejning. Dessutom förångades mer än 99,9 % av vätskan från de ursprungliga dropparna (för alla testade produkter) snabbt till gas och storleken på de kvarvarande, torkade partiklarna var mellan 2 och 4 µm. Vidare forskning inom området behövs, men förhoppningen är att rekommendationer och riktlinjer för städsprejanvändning ska kunna fastslås inom en snar framtid

Aerosol formation and emissions from realistic compartment fires

Firefighters are occupationally exposed to a large number of toxic compounds (IARC 2010). The occupational exposure of firefighters has been classified as potentially carcinogenic (class 2B, IARC; (Straif K. et al. 2007)). Poorly quantified emission factors and low understanding of when various aerosol emissions are likely to form during a fire event (initiation, combustion, extinguishing) inhibit efforts to reduce exposure by interventions to the firefighting strategy. The study was designed to evaluate firefighters’ exposure to air pollutants and to allow identification of how aerosol emissions respond to burning conditions and interventions of the firefighting. The study was conducted at the MSB firefighter training facility in Revinge outside Lund, Sweden. Eight small (5x3x2 m) sheds were built to imitate small compartment environments: apartment, bedroom, workshop, etc. These sheds were ignited under realistic fire scenarios (e.g., accident, arson) and later used for training new fire investigators (forensic police). Firefighter students and teachers monitored and extinguished the fires in similar procedures to real fire events. A supervisor monitored the combustion conditions, allowing or restricting fresh-air flow into the fire by opening or closing of the main door.Fire emissions were extracted from the fire through a 10 m (Ø 6 mm) stainless steel pipe, diluted ~1:50 with HEPA and active charcoal filtered air. The diluted emissions were monitored with a battery of aerosol monitoring instruments. Instrumentation included an aerosol mass spectrometer (Aerodyne SP-AMS, Billerica USA), an aethalometer (AE33, Magee Sci. USA), a differential mobility spectrometer (DMS500, Cambustion, UK), CO2 monitor (LI-COR, USA), and a NO/NO2 monitor (2BTech, USA). Complementary background measurements were positioned downwind or sidewind of the fires. With this equipment we collected data with the aim to resolve relationships between combustion conditions and pollution formation during different phases of a fire response. The results showed that total particle mass (PM1) emissions correlated with CO2 emissions and thus fire intensity. The emissions were speciated according to equivalent black carbon (eBC), organic aerosol (OA) and polycyclic aromatic hydrocarbon (PAH) derived from AMS data. When speciated, different particle emissions were found to depend on activities of the firefighting and the supervisor responsible for allowing or restricting fresh air into the combustion environment. Most evidently, we found that restricting the access to O2 by closing the door resulted in a sharp increase of OA and even more pronounced, PAH. PAH increased by several orders of magnitude, suggesting that PAH exposure-risks may increase drastically when fires become under-ventilated. Extinguishing the fire with water quickly decreased all particle emissions. The results described are illustrated in Figure 1.Further analysis involves additional off-line analyses, derivation of emission factors, time-resolved speciated emission analysis and evaluation of relationships between emissions, burning conditions and firefighting strategies

Exposing the Exposures : Assessing occupational aerosol exposures and their possible health and toxicological effects

According to the Global Burden of Disease study, occupational exposures to particulates, gases and fumes were responsible for 0.36 million deaths and 8.8 million disability-adjusted life years globally in 2015. This thesis focuses on two occupational groups that are at risk for developing adverse health effects from the time they spend in their working environments: cleaning workers and workers in the nanotechnology industry. For both of these occupational groups, who are affected by the introduction of new products into their occupational environments, knowledge is needed about the present exposure situations, as well as evaluations of the potential health and toxicological effects of these exposures.The overall aim of the research presented in this thesis was to provide a basis for the implementation of improvements of the working environments for these two occupational groups by addressing the research needs within them. Aerosol emissions and exposures present in the two occupational settings were characterized, and the potential health and toxicological effects that can possibly arise from these types of exposures were evaluated. Extensive methodological approaches were used, divided into the three overall categories of contextual information gathering, aerosol characterization, and health/toxicity assessment.To assess the working environment of cleaning workers, with a specific focus on the possible aerosol exposure generated during spray use, an initial phone inquiry of cleaning companies (n = 20) with a following survey among professional cleaning workers (n = 225) were conducted. Characterizations of the spray aerosol were performed with both off-line and on-line methods. A human chamber exposure study was then conducted to evaluate acute health effects due to the use of different cleaning methods.To assess the working environment in the nanotechnology industry, three different companies were studied. Contextual information was collected from the companies about the type of materials and processes they were handling. Workplace measurements were then conducted to characterize the current engineered nanomaterial (ENM) emission and exposure situations. Relevant toxicological assessments are also needed to evaluate the potential ENMs’ hazards. A comparative study of the toxicity of a common ENM assessed with different cell exposure systems was therefore carried out. The more advanced Nano Aerosol Chamber for In Vitro Toxicity (NACIVT) system was compared with two traditionally submerged toxicological exposure systems to understand the similarities and differences between them.Worker’s exposures could be determined within both occupations. We showed that the use of cleaning sprays results in an aerosol exposure, but with a large variety between different products. Between 2.7 and 32.2% of the liquid leaving the bottle during spraying remained airborne and could constitute potential airway exposure. We also showed that the nose was the part of the respiratory system most affected by spray use, but that switching to a foaming application method greatly reduced both the aerosol concentration and the observed negative health effects.At the nanotechnology companies, emissions and exposures were found from all three fibrous nanomaterials that were handled, foremost during the manual cleaning of the ENM production reactor and during the handling of both dry ENM powder and ENM-containing liquid. Comparing the different toxicological exposure systems revealed a higher sensitivity in the NACIVT system than the two traditionally submerged systems. This result encourages the use of more physiologically realistic cell exposure systems.The knowledge generated by the thesis research can be used to promote safe working environments. Exposure data together with hazard/toxicity information can be used to provide improved risk assessments. The comparison and evaluation of measurement techniques can be used in recommendations to occupational hygienists. The identification of processes that cause exposure events can be used by companies to implement suitable mitigation systems. All this can be done to achieve healthier workplace conditions

Characterization of airborne particles from cleaning sprays and their corresponding respiratory deposition fractions

Cleaning workers are exposed to many risk factors, including handling of cleaning products. Epidemiological studies show that they have a high incidence of asthma and other respiratory symptoms. Some studies have indicated an even higher incidence of asthma in individuals using cleaning sprays regularly. It is known that sprays produce an aerosol that can expose the respiratory system to chemicals. Knowledge of the physical characteristics of the airborne particles, as well as the characteristics of the gas phase, is needed to determine how they affect the respiratory tract and why they cause airway symptoms. The aim of this study was to characterize the aerosols from seven different ready-to-use trigger cleaning sprays in terms of total airborne mass fraction, particle size distribution, and new particle formation from ozone reactions. An additional aim was to calculate the respiratory deposition fraction of the measured particles. The total airborne mass fraction was determined by comparing the mass deposited on the chamber wall with the mass emitted from the bottle during spraying. Particle number concentration and size distribution of the airborne particles were measured using an aerodynamic particle sizer and a fast aerosol mobility size spectrometer. The total airborne mass fraction was between 2.7% and 32.2% of the mass emitted from the bottle, depending on the product. Between 0.0001% and 0.01% of the total airborne mass fraction consisted of residual particles. However, these particles had a mass median aerodynamic diameter between 1.9 µm and 3.7 µm, constituting a total respiratory deposition of up to 77%. New particle formation in the presence of ozone was also shown to vary between 5,000 cm−3 and 35,000 cm−3 depending on the product, in the studied settings. These findings confirm that a substantial part (up to 1/3) of the mass sprayed from the bottle does not reach the intended surface. Thus, the use of cleaning sprays can result in chemical airway exposure, with particles in the relevant size range for both nasal and alveolar deposition

Patient satisfaction after expenditure cutback and intervention to improve nursing care at a surgical clinic. At two-year follow-up.

Between 1991 and 1994 the number of beds in the surgical clinic at a central hospital in Southern Sweden was cut back by almost 50%. To develop the nursing care and to control the effects of the budgetary cuts, an intervention, including nursing care development, of an organization that would secure continuity in the nurse-patient relationship, individually planned care and quality assurance for aspects believed to be crucial to the quality of nursing care was implemented. The aim of this study was to analyse patients’ satisfaction with surgical nursing care between, under and after the last cut in expenditure and the concluded intervention. A patient satisfaction questionnaire covering such areas as: patient satisfaction with information and decisionmaking; patient satisfaction with contact and the staff-patient relationship; patient satisfaction with ward facilitles and the physical treatment or examination and patient satisfaction with various other aspects of care, was administered (1993 {pi}=131; 1994 {pi}=128). Subsample analysis showed lower scores for patient satisfaction if the respondents were women, young, or acutely ill when admitted. While surveys carried out between 1991 and 1993 showed an overall improvement in the quality of care, as measured by patient satisfaction, it remained at the same level in 1994 as in 1993, or decreased, regarding patient contacts with staff and physicians, involvement in decision-making, anxiety before examination/treatment, anxiety regarding professional secrecy, opportunity to influence the solution to their physical problems, chance to get sleep without being disturbed, physical nursing care and preparations before discharge. Thus a deterioration in quality seemed to take place in 1994 indicating that the cuts in expenditure may have been too hard and had been made at the expense of patient satisfaction

Real-Time Emission and Exposure Measurements of Multi-walled Carbon Nanotubes during Production, Power Sawing, and Testing of Epoxy-Based Nanocomposites

The use of manufactured nanomaterials is increasing globally. Although multi-walled carbon nanotubes (CNTs) are used in a wide range of applications, only limited data are available on emissions and exposures during CNT composite production. No exposure data using portable aethalometers in the personal breathing zone (PBZ) to monitor occupational exposure to CNTs have yet been published. The aim of this study was to characterize emissions of and exposures to CNTs during CNT composite production, sawing, and shear testing. We also investigated whether real-time aethalometer measurements of equivalent black carbon (eBC) could be used as a proxy filter sampling of elemental carbon (EC). The presence of CNTs as surface contamination in the production facility was monitored since this could contribute to airborne exposure.Methods: During CNT composite production in an industrial setting including both chemical and manufacturing laboratories, different work tasks (WTs) were studied with a combination of directreading instruments (aethalometer, aerodynamic particle sizer, condensation particle counter) and filter-based methods. Measurements were performed to monitor concentrations in the emission zone (EZ), PBZ, and background zone. The filter samples were analysed for EC and fibre concentration of CNTs using scanning electron microscopy (SEM). Additionally, surfaces in the facility were tape sampled for monitoring of CNT contamination, and analysed with SEM.Results: Clear eBC peaks were observed in the PBZ during several WTs, most clearly during open handling of CNT powder. Power sawing emitted the highest particle number concentration in the EZ of both nanoparticles and coarse particles, but no individual airborne CNTs, agglomerates, or aggregates were detected. Airborne CNTs were identified, for example, in a filter sample collected in the PBZ of a worker during mixing of CNT epoxy. The airborne CNT particles were large agglomerates which looked like porous balls in the SEM images. Significant EC exposures were found in the inhalable fraction while all respirable fractions of EC were below detection. The highest inhalable EC concentrations were detected during the composite production. No significant correlation was found between inhalable EC and eBC, most likely due to losses of large EC containing particles in the sampling lines and inside the eBC monitor. In total, 39 tape samples were collected. Surface contamination of CNTs was detected on eight surfaces in the chemical and manufacturing laboratories, mainly in the near-field zone. Elongated CNT-like features were detected in the sawdust after sawing of CNT composite.Conclusions: Characterization of a workplace producing CNT composite showed that open handling of the CNT powder during weighing and mixing of CNT powder material generated the highest particle emissions and exposures. The portable direct-reading aethalometer provided time-resolved eBC exposure data with complementary information to time-integrated EC filter samples by linking peak exposures to specific WTs. Based on the results it was not possible to conclude that eBC is a good proxy of EC. Surface contamination of CNTs was detected on several surfaces in the near-field zone in the facility. This contamination could potentially be resuspended into the workplace air, and may cause secondary inhalation exposure

Workplace Emissions and Exposures During Semiconductor Nanowire Production, Post-production, and Maintenance Work

BackgroundNanowires are a high-aspect-ratio material of increasing interest for a wide range of applications. A new and promising method to produce nanowires is by aerotaxy, where the wires are grown in a continuous stream of gas. The aerotaxy method can grow nanowires much faster than by more conventional methods. Nanowires have important properties in common with asbestos fibers, which indicate that there can be potential health effects if exposure occurs. No conclusive exposure (or emission) data from aerotaxy-production of nanowires has so far been published.MethodsDifferent work tasks during semiconductor nanowire production, post-production, and maintenance were studied. A combination of direct-reading instruments for number concentration (0.007–20 µm) and filter sampling was used to assess the emissions (a couple of centimeter from the emission sources), the exposure in the personal breathing zone (max 30 cm from nose–mouth), and the concentrations in the background zone (at least 3 m from any emission source). The filters were analyzed for metal dust composition and number concentration of nanowires. Various surfaces were sampled for nanowire contamination.ResultsThe particle concentrations in the emission zone (measured with direct-reading instruments) were elevated during cleaning of arc discharge, manual reactor cleaning, exchange of nanowire outflow filters, and sonication of substrates with nanowires. In the case of cleaning of the arc discharge and manual reactor cleaning, the emissions affected the concentrations in the personal breathing zone and were high enough to also affect the concentrations in the background. Filter analysis with electron microscopy could confirm the presence of nanowires in some of the air samples.ConclusionsOur results show that a major part of the potential for exposure occurs not during the actual manufacturing, but during the cleaning and maintenance procedures. The exposures and emissions were evaluated pre- and post-upscaling the production and showed that some work tasks (e.g. exchange of nanowire outflow filters and sonication of substrates with nanowires) increased the emissions post-upscaling