Classifying ozone as an air pollutant in the lower atmosphere In tropospheric air quality, ozone is best described as which type of pollutant?

Introduction / Context:
Ozone plays two contrasting roles: beneficial in the stratosphere where it absorbs harmful ultraviolet radiation, and harmful in the troposphere where it is a key component of photochemical smog. Understanding how tropospheric ozone forms is vital for controlling urban air pollution.

Given Data / Assumptions:

• Context is ground-level (tropospheric) ozone, not stratospheric ozone.
• Precursor emissions include nitrogen oxides (NOx) and volatile organic compounds (VOCs).

Concept / Approach:
Tropospheric ozone is not emitted directly; it forms through sunlight-driven reactions involving NOx and VOCs. Therefore, it is a classic secondary pollutant. The statement that ozone is “impervious to UV” is incorrect; stratospheric ozone absorbs UV-B and part of UV-C, which is why the ozone layer protects life on Earth.

Step-by-Step Solution:

Verification / Alternative check:
Air quality management focuses on precursor reductions, not direct ozone emissions, reinforcing the classification.

Why Other Options Are Wrong:

Common Pitfalls:
Conflating stratospheric and tropospheric ozone; the former is protective, the latter is a pollutant.

Final Answer:
a secondary pollutant.