Certified in Public Health (CPH) Practice Exam

What impact do chlorofluorocarbons (CFCs) have on the environment?

1. Contribute to greenhouse gases

2. Help in ozone layer recovery

3. Degrade the ozone layer

4. Reduce global warming potential

The correct answer is: Degrade the ozone layer

Chlorofluorocarbons (CFCs) are known primarily for their significant detrimental impact on the ozone layer. These chemicals, once commonly used in refrigeration, air conditioning, and aerosol sprays, release chlorine atoms when they are broken down by ultraviolet radiation in the stratosphere. The chlorine atoms can then react with and break apart ozone (O3) molecules, which are crucial for absorbing harmful ultraviolet (UV) radiation from the sun. The degradation of the ozone layer leads to increased UV radiation reaching the Earth's surface, which can result in higher incidence rates of skin cancer, cataracts, and negative effects on ecosystems, including harm to marine life and terrestrial plants. Understanding this destructive process is vital in appreciating the importance of international agreements like the Montreal Protocol, which aimed to phase out the use of CFCs and protect the ozone layer. The options that suggest benefits from CFCs, such as contributing to greenhouse gases, reducing global warming potential, or helping in ozone layer recovery, do not accurately reflect their environmental impact. In fact, CFCs are greenhouse gases as well, but their primary and most detrimental role is as ozone-depleting substances, making the choice regarding their degradation of the ozone layer the most pertinent.