What overall effect do CFCs and HCFCs have on the environment?

The overall effect of CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) on the environment is that they contribute to ozone depletion. These compounds, primarily used as refrigerants and in aerosol sprays, release chlorine and bromine when they are eventually broken down in the atmosphere. Once these elements reach the stratosphere, they interact with ozone (O3) molecules, leading to the destruction of ozone, which is crucial for blocking harmful ultraviolet (UV) radiation from the sun. This depletion can result in increased UV exposure, which poses serious risks to human health, wildlife, and ecosystems.

By contrast, the other options do not accurately represent the impact of CFCs and HCFCs. They do not promote plant growth; in fact, increased UV radiation due to ozone depletion can harm plants. Furthermore, these substances do not enhance air quality; rather, they can contribute to pollution and environmental degradation. Lastly, claiming that they have no effect on ozone is inconsistent with extensive scientific research demonstrating their significant role in ozone depletion.