Clearing the Air: Ozone-killing bromine is on the decline

Chemical analyses of Earth’s lower atmosphere show that the overall concentration of bromine, a component of many potent ozone-destroying chemicals, has dropped about 5 percent since reaching a peak in 1998. Besides being a promising sign for Earth’s beleaguered ozone layer, the decline validates the decision by many countries to regulate the production and use of the predominant bromine-releasing compound, some scientists say.