Coupling Computational Fluid Dynamics Simulations and Statistical Moments for Designing Healthy Indoor Spaces

Cross-contamination between occupants in an indoor space may occur due to transfer of infectious aerosols. Computational fluid dynamics (CFD) provides detailed insight into particle transport in indoor spaces. However, such simulations are site-specific. This study couples CFD with statistical moments and establishes a framework that transitions site-specific results to generating guidelines for designing “healthy” indoor spaces. Eighteen cases were simulated, and three parameters were assessed: inlet/outlet location, air changes per hour, and the presence/absence of desks. Aerosol release due to a simulated “sneeze” in a two-dimensional ventilated space was applied as a test case. Mean, standard deviation, and skewness of the velocity profiles and particle locations gave an overall picture of the spread and movement of the air flow in the domain. A parameter or configuration did not dominate the values, confirming the significance of considering the combined influence of multiple parameters for determining localized air-flow characteristics. Particle clustering occurred more when the inlet was positioned above the outlet. The particle dispersion pattern could be classified into two time zones: “near time”, \u3c60 \u3es, and “far time”, \u3e120 s. Based on dosage, the 18 cases were classified into three groups ranging from worst case scenario to best case scenario

Coupling Computational Fluid Dynamics Simulations and Statistical Moments for Designing Healthy Indoor Spaces

Cross-contamination between occupants in an indoor space may occur due to transfer of infectious aerosols. Computational fluid dynamics (CFD) provides detailed insight into particle transport in indoor spaces. However, such simulations are site-specific. This study couples CFD with statistical moments and establishes a framework that transitions site-specific results to generating guidelines for designing “healthy” indoor spaces. Eighteen cases were simulated, and three parameters were assessed: inlet/outlet location, air changes per hour, and the presence/absence of desks. Aerosol release due to a simulated “sneeze” in a two-dimensional ventilated space was applied as a test case. Mean, standard deviation, and skewness of the velocity profiles and particle locations gave an overall picture of the spread and movement of the air flow in the domain. A parameter or configuration did not dominate the values, confirming the significance of considering the combined influence of multiple parameters for determining localized air-flow characteristics. Particle clustering occurred more when the inlet was positioned above the outlet. The particle dispersion pattern could be classified into two time zones: “near time”, <60 s, and “far time”, >120 s. Based on dosage, the 18 cases were classified into three groups ranging from worst case scenario to best case scenario

Innovative inland brine disposal options

Growing demand, concerns over droughts, over-allocation of surface water resources, and depletion of freshwater aquifers have all made desalination of brackish groundwater an increasingly important option for inland communities. However, these communities must find a means to dispose of the concentrated saline residual waste stream in an environmentally sound manner. Evaporation ponds are one of the primary options, but this technology has a large land requirement, which makes it costly. A concern for large facilities is that this technology is one of the few treatment methods that offers decreasing returns to scale due to increasing boundary layer resistance for larger ponds. This study evaluated a number of innovative options for improving the performance of evaporation ponds. Viable methods identified from the literature are: 1) fabric evaporators, 2) wetted boundary layer breakers, 3) salt-tolerant plants, and 4) droplet spraying. Two cost models are developed, one for boundary layer breakers and one for droplet spraying. Incremental costs and incremental evaporation enhancements are compared with site-specific cost information for a wastewater treatment facility in California's Central Valley. Results indicate that both boundary layer breakers and spray technologies are cost-effective compared to a simple expansion of the pond area. Boundary layer breakers appear to be more cost-effective per gallon incremental capacity but have a lower evaporation enhancement capacity compared to droplet spraying (24% enhancement vs. 35% enhancement). For a new facility, an example calculation with preliminary cost information indicates that spray evaporation is more cost-effective because of avoided pond excavation and lining costs. Boundary layer breakers are preferred as a retrofit to an existing facility, if they provide sufficient additional capacity to avoid the need for an expansion of the pond

Influence of indoor conditions on microbial diversity and quantity in schools

HVAC systems consumes 37 % of the electricity in educational buildings. Energy consumption varies depending on the ventilation strategy. School buildings have a responsibility of ensuring energy performance and maintenance of indoor environmental quality for its occupants. This study assesses the efficiency of the ventilation system in terms of the microbes present in the spaces. Microorganisms and particulate matters were sampled in classrooms, locker rooms, libraries in two high schools and an elementary school. Six bacterial species and seven fungal species were identified. The most abundant microorganisms were Staphylococcus sp., Bacillus sp., and Micrococcus sp. Elementary school, especially kindergarten, showed higher microbial concentration and particulate matter as a result of higher human activity. Microbial concentration was influenced by the types of room in the same building with the same ventilation system. Canonical correspondence plot (CCA) determined that gender and school type have significant effects. The presence of Bacillus sp., Aerococcus sp., Corynebacterium sp., and Penicillium sp. was significantly related to gender, while Staphylococcus sp. and Alternaria sp. were related to type of school. The presence of Aerococcus sp. and Micrococcus sp. depended on the distance from the vent location. Relatively lower number of Aerococcus sp. was detected when the distance between sampling site and vent was less than 2 m. Micrococcus sp. was generally detected when the distance was < 3.5 m. The distance from the door was not significant

End of an era of administering erythropoiesis stimulating agents among Veterans Administration cancer patients with chemotherapy-induced anemia.

Erythropoisis stimulating agent (ESA) use was addressed in Food and Drug Administration (FDA) Oncology Drug Advisory Committee (ODAC) meetings between 2004 and 2008. FDA safety-focused regulatory actions occurred in 2007 and 2008. In 2007, black box warnings advised of early death and venous thromboembolism (VTE) risks with ESAs in oncology. In 2010, a Risk Evaluation Strategies (REMS) was initiated, with cancer patient consent that mortality and VTE risks were noted with ESAs. We report warnings and REMS impacts on ESA utilization among Veterans Administration (VA) cancer patients with chemotherapy-induced anemia (CIA). Data were from Veterans Affairs database (2003-2012). Epoetin and darbepoetin use were primary outcomes. Segmented linear regression was used to estimate changes in ESA use levels and trends, clinical appropriateness, and adverse events (VTEs) among chemotherapy-treated cancer patients. To estimate changes in level of drug prescription rate after policy actions, model-specific indicator variables as covariates based on specific actions were included. ESA use fell by 95% and 90% from 2005, for epoetin and darbepoetin, from 22% and 11%, respectively, to 1% and 1%, respectively, among cancer patients with CIA, respectively (