Consumption data for coal, petroleum, and natural gas are multiplied by their respective thermal conversion factors, which are in units of heat energy per unit of fuel consumed (i.e., per cubic foot, barrel, or ton), to calculate the amount of heat energy derived from fuel combustion. The thermal conversion factors are given in Appendix A of each issue of Monthly Energy Review, published by the Energy Information Administration (EIA) of the U.S. Department of Energy (DOE). These energy consumption data were multiplied by their respective carbon dioxide emission factors, which are called carbon content coefficients by the U.S. Environmental Protection Agency (EPA). These factors quantify the mass of oxidized carbon per unit of energy released from a fuel. In the U.S.A., they are typically expressed in units of teragrams of carbon (Tg-C = 1012 grams of carbon) per quadrillion British thermal units (quadrillion Btu = 1015 Btu, or ""quad""), and are highest for coal and lowest for natural gas. Results are given in teragrams of carbon emitted. To convert to carbon dioxide, multiply by 44/12 (= 3.67).