Tobacco expansion is the process of puffing leaves of tobacco to decrease the volume of tobacco used in cigarette production. Substitutes are reviewed on the basis of environmental and health risks, including factors such as ozone depletion potential, global warming potential, toxicity, flammability, and exposure potential. Lists of acceptableacceptableThis designation means that a substitute may be used, without restriction, to replace the relevant ODS within the end-use specified. For example, HCFC-22 is an acceptable substitute for R-502 in industrial process refrigeration. Note that all SNAP determinations apply to the use of a specific product as a substitute for a specific ODS in a specific end-use. and UnacceptableUnacceptableThis designation means that it is illegal to use a product as a substitute for an ODS in a specific end-use. For example, HCFC-141b is an unacceptable substitute for CFC-11 in building chillers. Note that all SNAP determinations apply to the use of a specific product as a substitute for a specific ODS in a specific end-use. substitutes are updated several times each year.

Note: SNAP-related information published in the Federal Register takes precedence over all information on this page.

Substitute	Trade Name(s)	ODPODPA number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of CFC-11. Thus, the ODP of CFC-11 is defined to be 1.0. Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. The halons have ODPs ranging up to 10. Carbon tetrachloride has an ODP of 1.2, and methyl chloroform's ODP is 0.11. HFCs have zero ODP because they do not contain chlorine. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, GWPs, and CAS numbers.	GWPGWPThe index used to translate the level of emissions of various gases into a common measure in order to compare the relative radiative forcing of different gases without directly calculating the changes in atmospheric concentrations. GWPs are calculated as the ratio of the radiative forcing that would result from the emissions of one kilogram of a greenhouse gas to that from the emission of one kilogram of carbon dioxide over a period of time (usually 100 years). Gases involved in complex atmospheric chemical processes have not been assigned GWPs. See lifetime.	Flammable	SNAP Listing Date	Listing Status	Further Information
Carbon Dioxide		0	1	No	March 18, 1994	Acceptable	New equipment only.
Propane		0	3	Yes	March 18, 1994	Acceptable	Propane tobacco expansion is a patented process. Flammability may be of concern for workers. Major sources of VOC emissions are subject to the New Source Review (NSR) program under the CAA.