Even though ground-level ozone is a health hazard, the ozone layer in the stratosphere is a health benefit because

The ozone layer absorbs a large portion of incoming UV radiation, which keeps ground-level ozone from forming. A higher percentage of UV radiation entering the troposphere would allow a greater amount of ozone to form in the troposphere. Ozone is a pollutant in the troposphere. By regulating the amount of UV radiation that enters the troposphere, the ozone layer also regulates the amount of ozone formation in the troposphere.

Explanation:

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