Environmental policy of the United States Environmental Protection Agency, were people with a history of opposition to the agency they were named to head. Since the environmental movement of the 1970s, the nature of environmental issues has changed. While the initial emphasis was on conventional air and water pollutants, which were the most obvious and easily measurable problems, newer issues are long-term problems that are not easily discernible and can be surrounded by controversy. Acid deposition, in the form of acid rain and dry deposition, is the result of sulfur and nitrogen dioxide being emitted into the air, traveling and landing in a different place, and
Underground coal gasification oxidants (air, oxygen) and steam to ignite and fuel the underground combustion process. Separate production wells are used to bring the product gas to the surface. The high pressure combustion is conducted at temperature of , but it may reach up to . The process decomposes coal and generates carbon dioxide (), hydrogen (), carbon monoxide (CO), methane (). In addition, there are small quantities of various contaminants including sulfur oxides (), mono-nitrogen oxides (), and hydrogen sulfide (). As the coal face burns and the immediate area is depleted, the oxidants injected are controlled by the operator. There are