Dalton's law of partial pressures and the hypothesis that water vapor equilibrium in a canister is identical to that established above liquid water are used to predict the variation of the percent relative humidity (%RH) of air released from canisters used in ambient air sampling, typically 6-L canisters pressurized with 18 L of air. When (and if) the water vapor partial pressure in a canister exceeds its saturation vapor pressure, water vapor condensation begins and the condensation rate equals the sampling rate of water vapor into the canister. Under constant temperature conditions, the air subsequently released from the canister is less humid than the original sample, following the relationship %RH = 100% (6 L/V) for V> V, where V is the residual air volume (referenced to atmospheric pressure), and V is shown to depend on the %RH of the ambient air sample. V is the residual air volume at which water is completely removed (except for adsorbed water vapor) from the canister wall. For V < V, the predicted %RH is constant and equal to its value at V. Experimental values agree reasonably well with predictions at both high (90%) and low (34%) RH. However, experimental values are often slightly displaced (usually towards lower values of %RH) for mid-range %RH (61%) and variations in %RH near V change from canister to canister.
The regulation of air pollution has reduced its toll on heart and lung diseases. For example, the Clean Air Act Amendments of 1990 helped avert an estimated 160,000 deaths and 86,000 hospitalizations in 2010 alone. 1 However, a growing body of research suggests that polluted air also puts our brain in harm's way. Chronic exposure to traffic-related pollutants may increase the risk of neurological disorders. 2 Both short-and long-term exposures have been associated with reduced human capital, including the academic performance of schoolchildren 3 and the productivity of workers across the adult lifespan.
Plastic is a popular packaging material, but also criticized as a symbol for the make‐use‐dispose economy because of its short lifespan, its dependency on fossil fuels, and its potential contribution to marine litter. To identify current and potential future key factors for the environmental performance of plastic packaging waste (PPW) management in Germany, a life cycle assessment considering five different pathways of PPW (including deposit‐refund systems, separately collected lightweight packaging waste, and treatment of non‐source‐separated residual waste) was performed. The analysis related to the year 2017 and also considered prospective changes in the background system until 2050 by adapting inventories to shared socioeconomic pathways in line with the Paris Agreement. Key factors for the environmental performance were determined by perturbation analysis. Source separation, quality and quantity of recycled plastics, and emissions from the thermal utilization of residues were identified as key factors for the environmental performance of PPW management. While benefits of PPW management are expected to decrease due to prospective system changes, source separation and the separation of plastics from residual waste gain in importance. Potential measures for improving the environmental performance should focus on long‐term key factors, especially separating PPW from the residual waste (in households or in waste treatment facilities) as well as increasing the quantities and qualities of recycled plastics. The present study showed that the evaluation of system performance in view of changing boundary conditions is key to identify optimal configurations of future PPW management.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.