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