IMPORTANCE Exposure to ozone has been associated with cardiovascular mortality, but the underlying biological mechanisms are not yet understood.OBJECTIVE To examine the association between ozone exposure and cardiopulmonary pathophysiologic mechanisms. DESIGN, SETTING, AND PARTICIPANTSA longitudinal study involving 89 healthy adult participants living on a work campus in Changsha City, China, was conducted from December 1, 2014, to January 31, 2015. This unique quasiexperimental setting allowed for better characterization of air pollutant exposure effects because the participants spent most of their time in controlled indoor environments. Concentrations of indoor and outdoor ozone, along with the copollutants particulate matter, nitrogen dioxide, and sulfur dioxide, were monitored throughout the study period and then combined with time-activity information and filtration conditions of each residence and office to estimate 24-hour and 2-week combined indoor and outdoor mean exposure concentrations. Associations between each exposure measure and outcome measure were analyzed using single-pollutant and 2-pollutant linear mixed models controlling for ambient temperature, secondhand smoke exposure, and personal-level time-varying covariates.MAIN OUTCOMES AND MEASURES Biomarkers indicative of inflammation and oxidative stress, arterial stiffness, blood pressure, thrombotic factors, and spirometry were measured at 4 sessions. RESULTSOf the 89 participants, 25 (28%) were women and the mean (SD) age was 31.5 (7.6) years. The 24-hour ozone exposure concentrations ranged from 1.4 to 19.4 parts per billion (ppb), corresponding to outdoor concentrations ranging from 4.3 to 47.9 ppb. Within this range, in models controlling for a second copollutant and other potential confounders, a 10-ppb increase in 24-hour ozone was associated with mean increases of 36.3% (95% CI, 29.9%-43.0%) in the level of platelet activation marker soluble P-selectin, 2.8% (95% CI, 0.6%-5.1%) in diastolic blood pressure, 18.1% (95% CI, 4.5%-33.5%) in pulmonary inflammation markers fractional exhaled nitric oxide, and 31.0% (95% CI, 0.2%-71.1%) in exhaled breath condensate nitrite and nitrate as well as a −9.5% (95% CI, −17.7% to −1.4%) decrease in arterial stiffness marker augmentation index. A 10-ppb increase in 2-week ozone was associated with increases of 61.1% (95% CI, 37.8%-88.2%) in soluble P-selectin level and 126.2% (95% CI, 12.1%-356.2%) in exhaled breath condensate nitrite and nitrate level. Other measured biomarkers, including spirometry, showed no significant associations with either 24-hour ozone or 2-week ozone exposures.CONCLUSIONS AND RELEVANCE Short-term ozone exposure at levels not associated with lung function changes was associated with platelet activation and blood pressure increases, suggesting a possible mechanism by which ozone may affect cardiovascular health.

The thermal performance of firefighters' protective clothing entrapping multiple air gaps and exposed to low heat fluxes has been studied using a newly designed bench-scale test apparatus. Different air gap sizes (0, 2 and 5 mm), and entrapped positions within the multiple fabric system between the outer shell, the moisture barrier, and the thermal liner, respectively, were investigated at three levels of thermal radiation (2, 5 and 10 kW/m2) over a prolonged period. The effect of air gap size and its position on the heat transfer in a multilayer fabric system are interpreted in terms of a theoretical flat multi-wall structure. The results show that the thermal protective performance of a multilayer fabric system is reduced under low-level heat flux with and without an air gap. It is indicated that the time for skin to burn in direct contact with the inner layer is increased with the size of the air gap, due to an increase in the total thermal resistance of the fabric combination and a decrease in heat radiation between two adjacent fabric layers separated by an air gap. The results also provide an insight into the contribution of the thermal resistance of each fabric layer and each air gap to the overall protective effect of the clothing system. The difference in the received heat flux with different air gap sizes in different positions shows that the effect of air gap size is related to its position.

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BackgroundAirborne transmission of respiratory infectious disease in indoor environment (e.g. airplane cabin, conference room, hospital, isolated room and inpatient ward) may cause outbreaks of infectious diseases, which may lead to many infection cases and significantly influences on the public health. This issue has received more and more attentions from academics. This work investigates the influence of human movement on the airborne transmission of respiratory infectious diseases in an airplane cabin by using an accurate human model in numerical simulation and comparing the influences of different human movement behaviors on disease transmission.MethodsThe Eulerian–Lagrangian approach is adopted to simulate the dispersion and deposition of the expiratory aerosols. The dose–response model is used to assess the infection risks of the occupants. The likelihood analysis is performed as a hypothesis test on the input parameters and different human movement pattern assumptions. An in-flight SARS outbreak case is used for investigation. A moving person with different moving speeds is simulated to represent the movement behaviors. A digital human model was used to represent the detailed profile of the occupants, which was obtained by scanning a real thermal manikin using the 3D laser scanning system.ResultsThe analysis results indicate that human movement can strengthen the downward transport of the aerosols, significantly reduce the overall deposition and removal rate of the suspended aerosols and increase the average infection risk in the cabin. The likelihood estimation result shows that the risk assessment results better fit the outcome of the outbreak case when the movements of the seated passengers are considered. The intake fraction of the moving person is significantly higher than most of the seated passengers.ConclusionsThe infection risk distribution in the airplane cabin highly depends on the movement behaviors of the passengers and the index patient. The walking activities of the crew members and the seated passengers can significantly increase their personal infection risks. Taking the influence of the movement of the seated passengers and the index patient into consideration is necessary and important. For future studies, investigations on the behaviors characteristics of the passengers during flight will be useful and helpful for infection control.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2334-14-434) contains supplementary material, which is available to authorized users.

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