California Environmental Quality Act Office of Planning and Research to develop and recommend new guidelines to analyze greenhouse gas impacts under CEQA. California’s Natural Resources Agency adopted new guidelines on December 31, 2009, requiring lead agencies to analyze greenhouse gas emissions under section 15064.4 during their CEQA review through California. The major category of greenhouse gas emissions resulting from human activities is carbon dioxide. Several other primary gases also include methane, nitrous oxide, sulfur hexafluoride, perfluorocarbons, and hydrofluorocarbons. Greenhouse gas sources resulting from project construction activities are typically generated from transportation of materials to the project site and petrol based equipment used during construction
Sulfur hexafluoride with satisfactory accuracy at very low concentrations, and the Earth's atmosphere has a negligible concentration of . Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St. John's Wood tube station in London, United Kingdom on 25 March 2007. The gas was released throughout the station, and monitored as it drifted around. The purpose of the experiment, which had been announced earlier in March by the Secretary of State for Transport Douglas Alexander, was to investigate how toxic gas might spread throughout London Underground stations and buildings during a terrorist attack. Sulfur hexafluoride is also routinely