Most gases used in anesthesiology eventually end up in the atmosphere where they trap heat even more effectively than carbon dioxide. iStockphoto.com hide caption

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A CT scan of the brain shows the cerebellum, a small portion of each temporal lobe, and the sinuses. Andrew Ciscel via Wikimedia Commons hide caption

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Army Captain William Krueger studies CT scans at the National Naval Medical Center in Bethesda, Md. CWO4 SETH ROSSMAN/NAVY VISUAL NEWS SERVICE hide caption

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CT Scans Modestly Cut Deaths Of Smokers In Study
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