Investigations of some aspects of atmospheric pollution by anaesthetic gases. I: Diffusion of halothane across plastic and rubber tubes.
Plastic and rubber tubing, of the types used frequently to convey anaesthetic gases to and from the patient, or anaesthetic waste gases out of the operating theatre, were assessed for their capacity to allow diffusion of halothane through the tube wall. The magnitude of this effect has been calculated in relation to pollution of the operating theatre atmosphere under different circumstances.
Environmental Pollution by Anaesthetic Agents: A Consideration for Developing Countries
tuating quantity of auditory, visual and tactile stimuli, which are superimposed upon an innate varying background of fatigue, stress and emotion. Performance after exposure to sub-anaesthetic doses of anaesthetic agents can be measured in volunteers performing audiovisual tasks, reaction-time tests, psychomotor tests and memory and learning tests. Conflicting reports have been produced. Some workers have reported subtle additive effects of traces of various anaesthetic agents on such parameters (Bentin et al. 1978a,b, Bruce et al. 1974, Bruce & Bach 1976). However, others conclude that commonly found theatre levels of pollution in the absence of active scavenging are unlikely to affect performance (Frankhuisen et al. 1978, Smith & Shirley 1977, Smith 1978, Gambill et al. 1979) except possibly during use of the Magill circuit when local high levels can occur, or in the presence of other factors interrelating to low dose exposure (Smith & Shirley 1978). Performance tests comparing operating theatre staff and non-theatre hospital staff have suggested that theatre staff develop tolerance to anaesthetic gas exposure, possibly by enzyme induction (Kortilla, Pfaffli, Linnoila et al. 1978, Kortilla, Pfaffli & Ertamon 1978). Therefore, although i t is difficult to demonstrate a doseresponse relation between anaesthetic concentration and performance, it would seem wise to reduce the “dose of pollutants given” to minimal safe levels, in order to ensure that performance of theatre staff is maintained a t as high a level as possible. Environmental pollution by anaesthetic agents: A consideration for developing countries
Geographic And Environmental Influence On Maya Settlement Patterns Of The Northwest Yucatan: An Explanation For The Sparsely Settled Western Cenote Zone
Most settlement pattern research and GIS analysis of the ancient Maya of the Northern Yucatan have focused on water availability in a dry landscape where cenotes are often the only water source. While water is of paramount importance, permanent settlement secondarily requires farmable soil, a resource often as precious as water in many parts of the Yucatan. The dynamics between these resources reveal areas of ideal settlement and more challenging landscapes for which the Maya developed strategies to overcome environmental conditions. A region of the southwest "Cenote Zone", however, appears to have presented the ancient Maya with insurmountably poor environmental conditions despite abundant water resources. The lack of dense population and stone architecture in this area emphasizes the lack of a simple correlation between cenotes and settlement. This thesis uses GIS analysis to identify and explore such problematic settlement areas to better understand the factors and complexities involved in the more successful settlements of neighboring regions. iv This work is dedicated to my late father, who first introduced me to the Mundo Maya through a visit to the ruins of Tikal at the age of nine, and who instilled in me strength, curiosity, and a love for exploring the world. v ACKLOWLEDGEMENTS I'd like to acknowledge Dr. Arlen Chase and Dr. Diane Chase for providing such outstanding opportunities and instruction, and for leading by example both in the field and in the classroom. Dr. John Walker for his eye-opening perspectives, GIS instruction, inspiring hard-working attitude, and patience in the field. Dr. Clifford Brown and Dr. Walter Witschey for their invaluable correspondence and for their contributions to mapping and GIS data of Maya sites.