Bad ozone is found in which atmospheric layer?

• A. Stratosphere
• B. Troposphere
• C. Mesosphere
• D. Exosphere

Answer: (B)

Bad ozone is found in the troposphere. This is the layer near the Earth’s surface where sunlight interacts with pollutants like nitrogen oxides from vehicles and volatile organic compounds from fuels and solvents. Those reactions create ozone at ground level, so this layer accumulates the harmful ozone that irritates eyes and lungs, reduces lung function, and worsens asthma—especially on sunny, traffic-heavy days. In contrast, ozone high up in the stratosphere forms the protective ozone layer that shields living things from most of the sun’s ultraviolet radiation, so it’s not considered “bad” ozone. The mesosphere and exosphere are much higher and not the source of ground-level ozone pollution.