What Causes Ground-Level Ozone?
Ground-level ozone is created when a mixture of air pollutants from a variety of sources — such as the fumes from our vehicles, lawnmowers, and boats, or emissions from power plants and industrial facilities — react in sunlight. The main ozone-causing pollutants are volatile organic compounds (VOCs) and nitrogen oxides (NOx). Because heat and sunlight are also important factors in ground-level ozone formation, ozone pollution is primarily a concern from April through October. Motor vehicles account for about 30-40% of the ozone-causing pollutants in the Baltimore and Washington areas.
