Environmental Protection Agency (EPA) MVAC Certification

Which chemical compounds are known for contributing to ozone layer depletion?

1. Hydrofluorocarbons (HFCs)

2. Chlorofluorocarbons (CFCs)

3. Carbon monoxide

4. Ammonia

The correct answer is: Chlorofluorocarbons (CFCs)

Chlorofluorocarbons (CFCs) are indeed the chemical compounds that contribute significantly to ozone layer depletion. They release chlorine atoms into the stratosphere when they are broken down by ultraviolet (UV) radiation. These chlorine atoms are highly reactive and can destroy thousands of ozone molecules, which are crucial for absorbing harmful UV radiation from the sun. CFCs were widely used in refrigeration, air conditioning, foam production, and aerosol propellant. Their ability to persist in the atmosphere for long periods further exacerbates their negative impact on the ozone layer. As a result of their harmful effects, the production and use of CFCs have been largely phased out under the Montreal Protocol, an international treaty aimed at protecting the ozone layer. Other options such as hydrofluorocarbons (HFCs) are known as greenhouse gases but do not contribute to ozone depletion, carbon monoxide primarily affects air quality and not ozone specifically, and ammonia is not associated with ozone layer effects. Thus, the main focus on CFCs is warranted in discussions about ozone depletion due to their significant and direct impact.