Electronic cigarette usage is increasing worldwide, yet there is a paucity of information on the respiratory health effects of electronic cigarette aerosol exposure. This study aimed to assess whether exposure to electronic cigarette (e-cigarette) aerosol would alter lung function and pulmonary inflammation in mice and to compare the severity of any alterations with mice exposed to mainstream tobacco smoke. Female BALB/c mice were exposed for 8 wk to tobacco smoke, medical air (control), or one of four different types of e-cigarette aerosol. E-cigarette aerosols varied depending on nicotine content (0 or 12 mg/ml) and the main excipient (propylene glycol or glycerin). Twenty-four hours after the final exposure, we measured pulmonary inflammation, lung volume, lung mechanics, and responsiveness to methacholine. Mice exposed to tobacco cigarette smoke had increased pulmonary inflammation and responsiveness to methacholine compared with air controls. Mice exposed to e-cigarette aerosol did not have increased inflammation but did display decrements in parenchymal lung function at both functional residual capacity and high transrespiratory pressures. Mice exposed to glycerin-based e-cigarette aerosols were also hyperresponsive to methacholine regardless of the presence or absence of nicotine. This study shows, for the first time, that exposure to e-cigarette aerosol during adolescence and early adulthood is not harmless to the lungs and can result in significant impairments in lung function.

This work examined the thermal behaviour of diesel engine produced soot and commercial carbon black using thermogravimetric analysis (TGA). It was found that during TGA analysis of the carbon matrices (at a temperature range commonly used for soot-in-oil content determination), a gradual mass loss occurred. This was attributed to pyrolysis effects and combustion processes occurring due to poor hydrodynamic design of some commercial thermobalances. This process resulted in a significant mass loss of the carbon during TGA. This finding may strongly effect soot-in-oil analysis conducted using current methods. Experiments were conducted using a range of soot-in-oil mixtures according to the widely used thermogravimetric standard method ASTM 5967-08 which showed a significant underestimation of the soot content in the oil as a result of carbon mass loss due to combustion and/or pyrolysis effects. An improved oil analysis method is proposed which provides a significantly increased accuracy of soot determination in lubricant oils.

This study investigated the influence of flow interruptions on the filtration performance of two different multi-layered fibrous filters during liquid aerosol filtration. It was found that both types of filters experienced a significant secondary loading stage, though they had reached a steady state for continuous flow. The filters showed distinctive increases in pressure drop and filter saturation until a second equilibrium state was reached. This second equilibrium state was attributed to a rearrangement of liquid in the filter during the breaks, clogging previously free passages. The ratio of shear and capillary forces was found to determine whether these passages were able to be "cleaned" once airflow was recommenced. Based on these findings, the airflow required to clean fully saturated filters was investigated and a phenomenological model developed to describe this behaviour. Furthermore, it was found that filters could be cleaned and reused, whereby they would return to one of the previous steady states (continuous or discontinuous flow). The experiments conducted in this work represent a more realistic test for oil-mist (or coalescing) filters than typical laboratory testing. Furthermore, it is hoped that they will help to bridge the gap between laboratory and field test results.

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