Environmental Protection Agency (EPA) MVAC Certification

Which statement is true regarding the ozone at ground level and in the stratosphere?

1. Both are harmful pollutants

2. Ozone at ground level is beneficial

3. Ozone in the stratosphere is a harmful pollutant

4. Ozone at ground level is a harmful pollutant

The correct answer is: Ozone at ground level is a harmful pollutant

Ozone at ground level, often referred to as tropospheric ozone, is indeed a harmful pollutant. It forms as a result of the chemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. Ground-level ozone can cause a variety of health problems, including respiratory issues, throat irritation, and exacerbation of asthma. Additionally, it can harm vegetation and ecosystems, negatively impacting agriculture and natural resource management. In contrast, ozone in the stratosphere plays a beneficial role. It constitutes the ozone layer, which absorbs a significant amount of the sun's harmful ultraviolet (UV) radiation, protecting living organisms on Earth from these damaging rays. Without this ozone layer, increased UV exposure would lead to higher rates of skin cancer and other health issues, as well as detrimental effects on wildlife and plant life. Thus, the distinction between ground-level ozone and stratospheric ozone underscores the context-dependent nature of ozone: while it is harmful at ground level, it serves a protective function in the stratosphere. This understanding is crucial for environmental science and public health, framing the need for effective air quality regulations to manage ground-level ozone pollution.