Library Index » Science Encyclopedia » A Hole in the Sky: Ozone Depletion - Earth's Protective Ozone Layer, Evidence Of Ozone Depletion, Consequences Of Ozone Depletion, Ozone-depleting Chemicals

A Hole in the Sky: Ozone Depletion - Production And Demand Of Ozone-depleting Chemicals

cfc emissions hcfc halon

In 1950 the worldwide production of CFCs was approximately 42,000 tons annually; in 1988, it peaked at 1.3 million tons. By the late 1990s, production had dropped to an estimated 300,000 tons.

In the industrial world, many countries did more than was required by the protocol. As a result, when the official CFC phaseout date arrived, most industrial nations were ready, and some had phased out ozone-depleting substances before they were required to. By the end of 1994, the European Union no longer permitted CFCs. In addition to banning Freon in 1997, the Clean Air Act required the United States to end the use of methyl bromide by 2001—nine years ahead of protocol requirements.

Although CFCs are no longer used in new applications, existing users can continue using them provided they are maintained under strict regulation, such as being replenished and "reclaimed" by authorized technicians. There are other exceptions to the ban, including medical inhalers, which commonly use CFCs as propellants.

U.S. Emissions and Markets

Title VI of the 1990 Clean Air Act Amendments (PL 101-549) is the United States' primary response to ozone depletion. As part of the act, the U.S. Congress approved a provision requiring the president to speed up the schedule for chemical phaseout if new evidence warranted it. In fact, new data did become available, including worrisome evidence that showed ozone depletion was occurring over the Northern Hemisphere.

U.S. emissions of ozone-depleting substances for 1990 and 1995–2001 are shown in Table 3.3. Emissions of CFCs, carbon tetrachloride, and methyl chloroform have all decreased, some significantly. Halon-1301 emissions have also decreased since 1990. However, emissions of halon-1211 actually increased by a small amount.

Figure 3.5 compares annual emissions of major ozone-depleting substances from 1990 to 2001. Although emissions of CFCs have declined dramatically, emissions of HCFC-22 (the most widely used CFC substitute) have risen due to increased production. Figure 3.6 compares emissions of major ozone-depleting substances for 2001.

In 1999 the EPA published an analysis of the market for CFC-12 over the next decade (Report on the Supply and Demand of CFC-12 in the United States). The agency estimated that 67 million units using CFC-12 would still

TABLE 3.3
Emissions of ozone-depleting substances, 1990 and 1995–2001
[in gigagrams (Gg)]

Compound 1990 1995 1996 1997 1998 1999 2000 2001
Class I
CFC-11 53.5 36.2 26.6 25.1 24.9 24.0 22.8 22.8
CFC-12 112.6 51.8 35.5 23.1 21.0 14.0 17.2 21.3
CFC-113 52.7 17.1 + + + + + +
CFC-114 4.7 1.6 + + + + + +
CFC-115 4.2 3.0 3.2 2.9 2.7 2.6 2.3 1.5
Carbon tetrachloride 32.3 4.7 + + + + + +
Methyl chloroform 316.6 92.8 + + + + + +
Halon-1211 1.0 1.1 1.1 1.1 1.1 1.1 1.1 1.1
Halon-1301 1.8 1.4 1.4 1.3 1.3 1.3 1.3 1.2
Class II
HCFC-22 34.0 39.3 41.0 42.4 43.8 74.1 79.1 80.5
HCFC-123 + 0.6 0.7 0.8 0.9 1.0 1.1 1.2
HCFC-124 + 5.6 5.9 6.2 6.4 6.5 6.5 6.5
HCFC-141b 1.3 9.9 9.9 8.8 9.7 10.9 10.9 10.7
HCFC-142b 0.8 3.6 4.0 4.3 4.7 5.0 5.4 5.8
HCFC-225ca/cb + + + + + + + +
Note: Does not exceed 0.05 Gg
SOURCE: "Table ES-13: Emissions of Ozone Depleting Substances (Gg)," in Inventory of U.S. Greenhouse Gas Emissions and Sinks: 19902001, U.S. Environmental Protection Agency, Office of Atmospheric Programs, Washington, DC, April 15, 2003

be in use in the United States in the year 2005. Nearly 90 percent of these units are refrigerated appliances. Mobile air conditioners comprise most of the remainder. The number of units using CFC-12 is expected to fall steadily through 2010.

Demand for CFC-12 is expected to decline as substitutes increase and aging equipment is replaced. The EPA estimated demand for CFC-12 in 1999 at 23 million pounds. By 2005 U.S. consumers will demand approximately 3 million pounds of CFC-12. Mobile air conditioning accounts for 80 percent of this demand. The remainder includes commercial refrigeration at supermarkets and cold storage warehouses, industrial processes, refrigerated appliances, and refrigerated transport.

Recycled halon and inventories produced before January 1, 1994 are the only supplies now available. It is legal under the Montreal Protocol and the U.S. Clean Air Act to import recycled halon, but each shipment requires approval from the EPA. Certain uses, such as fire protection, are classified as "critical use" and are permitted as long as supplies remain. The EPA also maintains a list of acceptable substitutes for halon.

A Hole in the Sky: Ozone Depletion - Substitutes And New Technologies [next] [back] A Hole in the Sky: Ozone Depletion - Montreal Protocol Science

User Comments

Your email address will be altered so spam harvesting bots can't read it easily.
Hide my email completely instead?

Cancel or