What is the Role of Chlorofluorocarbons in Ozone Depletion?

Chlorofluorocarbons (CFCs), along with other chlorine, and bromine-containing compounds, have been implicated in the accelerated depletion of ozone in the Earth's stratosphere. CFCs were developed in the early 1930s and are used in a variety of industrial, commercial, and household applications.

Disease substances are non­toxic, non-flammable, and non-reactive with other chemical compounds. These desirable safety characteristics, along with their stable thermodynamic properties, make them ideal for many applications such as coolants for commercial and home refrigeration units, aerosol, propellants, electronic cleaning solvents and blowing agents.

Not until 1973 chlorine was found to be a catalytic agent in ozone destruction, Catalytic destruction of ozone removes the odd oxygen species [Atomic oxygen (O) and ozone (03)] while leaving chlorine unaffected.

This process was known to be potentially damaging the ozone layer, but conclusive evidence of stratospheric ozone loss was not discovered until 1984. Announcement of polar ozone depletion over Antarctica in March 1985 prompted scientific initiatives to discover the Ozone Depletion Process, along with calls to freeze or diminish production of chlorinated fluorocarbons.

A complex scenario of atmospheric dynamics, solar radiation, and chemical reaction was found to explain the anomalously low levels of ozone during the polar spring time. Recent expeditions to the Arctic regions show that similar processes can occur in the northern hemisphere, but to a somewhat lesser degree due to warmer temperatures and erratic dynamic patterns.

Despite rapid phase-out of CFCs ozone levels are expected to be lower than pre-depletion levels for several decades due to the long stratospheric lifetimes of CFCs. These compounds are carried into the stratospheric where they can undergo hundreds of catalytic cycles involving ozone before being scavenged by other chemical species.