Effect of outside air ventilation rate on volatile organic compound concentrations in a call center

A study of the relationship between outside air ventilation rate and concentrations of volatile organic compounds (VOCs) generated indoors was conducted in a call center office building. The building, with two floors and a total floor area of 4600 m², is located in the San Francisco Bay Area, CA. Ventilation rates were manipulated with the building's four air handling units (AHUs). VOC and CO₂ concentrations in the AHU returns were measured on 7 days during a 13-week period. VOC emission factors were determined for individual zones on days when they were operating at near steady-state conditions. The emission factor data were subjected to principal component (PC) analysis to identify groups of co-varying compounds. Potential sources of the PC vectors were ascribed based on information from the literature. The per occupant CO₂ generation rates were 0.0068–0.0092 l s⁻¹. The per occupant isoprene generation rates of 0.2–0.3 mg h⁻¹ were consistent with the value predicted by mass balance from breath concentration and exhalation rate. The relationships between indoor minus outdoor VOC concentrations and ventilation rate were qualitatively examined for eight VOCs. Of these, acetaldehyde and hexanal, which likely were associated with material sources, and decamethylcyclopentasiloxane, associated with personal care products, exhibited general trends of higher concentrations at lower ventilation rates. For other compounds, a clear inverse relationship between VOC concentrations and ventilation was not observed. The net concentration of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate isomers, examples of low-volatility compounds, changed very little with ventilation likely due to sorption and re-emission effects. These results illustrate that the efficacy of ventilation for controlling VOC concentrations can vary considerably depending upon the operation of the building, the pollutant sources and the physical and chemical processes affecting the pollutants. Thus, source control measures, in addition to adequate ventilation, are required to limit concentrations of VOCs in office buildings.     

MOVEMENT AND WAYFINDING IN THE KING SAUD UNIVERSITY BUILT ENVIRONMENT: A LOOK AT FRESHMAN ORIENTATION AND ENVIRONMENTAL INFORMATION

One potentially significant, yet hardly investigated, criterion for postoccupancy evaluation is the legibility of a setting—the degree to which a building or group of buildings facilitate the ability of users to find their way around. Legibility is one of the foundation concepts of environmental psychology, yet it has not often been considered enough as a guiding principle in design. The purpose of this paper is to analyse spatial orientation and wayfinding problems encountered by newcomers (freshman students) at the King Saud University (KSU) campus, Saudi Arabia, and to test/relate this to Lynch's elements of the image of cities. The analysis draws on previous research findings, theories, and more general observations, as well as observations made of wayfinding performance and map sketching by 30 high-school students likely to soon enroll at the university. Many specific problems with orientation and the architectural legibility of the buildings are identified and discussed. Emphasis is placed upon physical-setting variables that are likely to affect the ease with which spatial orientation and wayfinding are accomplished. These include the following facets of the KSU built environment: degree of differentiation; degree of visual access; and complexity of spatial layout.Legible buildings within which people can effectively maintain their orientation and find their way, according to this research, are in no way simplistic, dull, or boring; on the contrary, settings must possess distinctive landmarks and regions which, along with understandable path networks, allow users to know where they are and how to make their way to desired destinations. Coherent and legible environments are important in the lives of the people who use them. The movement of people through buildings and the factors that influence whether or not they are able to find their way need to continue to be of significance to both researchers and practitioners.     

Effectiveness of Radon Control Techniques in Fifteen Homes

Radon control systems were Installed and evaluated In fourteen homes In the Spokane River Valley/Rathdrum Prairie and In one home In Vancouver, Washington. Because of local soil conditions, subsurface ventilation (SSV) by pressurlzatlon was always more effective In these houses than SSV by depressurlzatlon In reducing Indoor radon levels to below guidelines. Basement overpressurlzatlon was successfully applied In five houses with airtight basements where practical-sized fans could develop an overpressure of 1 to 3 Pascals. Crawlspace ventilation was more effective than crawlspace Isolation in reducing radon entry from the crawlspace, but had to be used In conjunction with other mitigation techniques, since the houses also had basements. Indoor radon concentrations In two houses with alr-toalr heat exchangers (AAHX) were reduced to levels Inversely dependent on the new total ventilation rates and were lowered even further In one house where the air distribution system was modified. Sealing penetrations In the below-grade surfaces of substructures was relatively Ineffective In controlling radon. Operation of the radon control systems (except for the AAHX’s) made no measureable change in ventilation rates or Indoor concentrations of other measured pollutants. Installation costs by treated floor area ranged from approximately $4/m² for sealing to $28/m² for the AAHX’s. Based on the low electric rates for the region, annual operating costs for the active systems were estimated to be approximately $60 to $170.     

Prenatal findings in generalized amyoplasia

Amyoplasia is a rare, sporadic condition characterized by different degrees of maldevelopment of the skeletal muscles, which are replaced by fibrous and fatty tissue. In this report, we present a case of generalized amyoplasia presenting at 19 weeks' gestation. The most striking finding was the absence of fetal movements, resulting in severe multiple congenital contractures, hydrops, and polyhydramnios. At autopsy, histological examination of the skeletal muscle showed small groups of poorly developed fibres within areas of fat. This report suggests that generalized amyoplasia could be a common cause of severe forms of multiple congenital contractures, but is probably underdiagnosed at post-mortem because of inadequate examination of muscles. Definitive diagnosis is important in determining the risks of recurrence in these cases.     

Intrauterine rescue transfusion in monochorionic multiple pregnancies with recent single intrauterine death

To assess the role of fetal blood sampling and intrauterine transfusion in monochorionic (MC) multiple pregnancy complicated by single intrauterine death (IUD), we reviewed ten cases over a 4-year period in a tertiary referral centre which underwent fetal blood sampling within 24 h of death of its MC co-twin. Intrauterine rescue transfusion was performed in all seven anaemic fetuses (hematocrit; Hct<30%) to raise the fetal Hct to ≥40%. The rationale was to prevent death and/or brain injury. Two fetuses, which were severely acidaemic at blood sampling, died in utero within 24 h of the procedure. In two cases, the surviving twins manifested abnormal sonographic findings of the fetal brain 2–5 weeks later and underwent late termination. In two cases, the pregnancies continued uneventfully until delivery at 35 and 40 weeks' gestation with good neonatal outcome. In one case the co-twin delivered 1 week later at 29 weeks but died within 12 h. Fetuses without anaemia were not transfused and had normal clinical outcomes. We suggest that intrauterine rescue transfusion before the development of severe acidaemia in anaemic surviving MC co-twins may prevent fetal death, but does not necessarily prevent brain injury. Until its role becomes clearer, we recommend that its use be restricted to situations in which the parents and the local jurisdiction allow late termination as an option if brain injury subsequently manifests on ultrasound. Copyright © 2001 John Wiley & Sons, Ltd.     

Spatial and temporal trends of selected trace elements in liver tissue from polar bears (Ursus maritimus) from Alaska, Canada and Greenland

Spatial trends and comparative changes in time of selected trace elements were studied in liver tissue from polar bears from ten different subpopulation locations in Alaska, Canadian Arctic and East Greenland. For nine of the trace elements (As, Cd, Cu, Hg, Mn, Pb, Rb, Se and Zn) spatial trends were investigated in 136 specimens sampled during 2005-2008 from bears from these ten subpopulations. Concentrations of Hg, Se and As were highest in the (northern and southern) Beaufort Sea area and lowest in (western and southern) Hudson Bay area and Chukchi/Bering Sea. In contrast, concentrations of Cd showed an increasing trend from east to west. Minor or no spatial trends were observed for Cu, Mn, Rb and Zn. Spatial trends were in agreement with previous studies, possibly explained by natural phenomena. To assess temporal changes of Cd, Hg, Se and Zn concentrations during the last decades, we compared our results to previously published data. These time comparisons suggested recent Hg increase in East Greenland polar bears. This may be related to Hg emissions and/or climate-induced changes in Hg cycles or changes in the polar bear food web related to global warming. Also, Hg:Se molar ratio has increased in East Greenland polar bears, which suggests there may be an increased risk for Hg(2+)-mediated toxicity. Since the underlying reasons for spatial trends or changes in time of trace elements in the Arctic are still largely unknown, future studies should focus on the role of changing climate and trace metal emissions on geographical and temporal trends of trace elements.