Ozone is a gas naturally present in Earth's atmosphere. Unlike regular oxygen, which contains two oxygen atoms (O2), ozone contains three oxygen atoms (O3). A molecule of regular oxygen can be converted to ozone by ultraviolet (UV) radiation, electrical discharge (such as from lightning), or complex chemical reactions. These processes split apart the two oxygen atoms, which are then free to…
Many scientists believe that the introduction of certain chemicals into the stratosphere alters the natural ozone balance by depleting ozone molecules. Chlorine and bromine atoms are particularly destructive. They can bind to loose oxygen atoms and prevent them from reforming either oxygen or ozone. Chlorine and bromine are found in the sea salt from ocean spray. Chlorine is also present in the fo…
Ironically, destruction of the ozone layer at the upper levels could increase the amount of ozone at the Earth's surface. In addition, the decline in stratospheric ozone is thought to increase hydrogen peroxide in the stratosphere, FIGURE 3.2 Altitude profile and distribution of ozone contributing to acid rain. The ozone layer acts as a protective shield against UV radiation. As ozone…
Most ozone destruction in the atmosphere is believed to be anthropogenic (caused by humans). In 1999 the World Meteorological Organization in Geneva, Switzerland, estimated that only 18 percent of the sources contributing to ozone depletion were natural. The remaining 82 percent of sources contributing to ozone depletion were industrial chemicals. The blame is largely placed on chemicals developed…
CFCs and halons were widely used in thousands of products and represented a significant share of the international chemical industry, with billions of dollars in investment and hundreds of thousands of jobs. Ozone depletion was a global problem that necessitated international cooperation, but nations mistrusted one another's motives. As with the issues of global warming and pollution, devel…
Implementation and enforcement of the Montreal Protocol have been aggravated by two factors—the reluctance of many countries to ratify amendments to the Protocol and the thriving black market in banned chemicals. The United Nations reported that 186 countries had ratified the original Montreal Protocol as of January 2004. In total, four amendments to the Protocol have been adopted. These ar…
Article 6 of the Montreal Protocol requires that the ratifying nations base their decision-making on scientific information assessed and presented by an international panel of ozone experts. This panel includes the World Meteorological Organization (WMO), the United Nations Environment Programme (UNEP), the European Commission, and two U.S. organizations—the National Oceanic and Atmospheric…
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…
As pressure increased to discontinue use of CFCs and halons, substitute chemicals and technologies began to be developed. One of the most popular substitutes is a class of compounds called hydrofluorocarbons (HFCs). HFCs do not contain chlorine, a potent ozone destroyer. They are also relatively short-lived in the atmosphere. Most survive intact for less than twelve years. This means that HFCs do …
In March 2004 the Gallup Organization conducted its annual poll of Americans' beliefs and attitudes about environmental issues. The results show that damage to the Earth's ozone layer ranks very low on the list of environmental problems about which Americans are worried. (See Figure 1.8 in Chapter 1.) Only 33 percent of those asked in 2004 expressed a great deal of worry about damage…
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