What is ground-level ozone?

Ground-level ozone is formed when hydrocarbons (VOCs) and nitrogen oxides (NOx) bake in the sun. These gases come from unburned fuel and solvents, tailpipe and stack emissions, and from activities of homeowners and individuals. When temperatures approach 90 degrees, the radiation index is high and the mixing of air currents is limited, ozone can increase to unhealthful levels.

Ozone usually peaks in the late afternoon. Symptoms of breathing ground-level ozone include chest pain, coughing, nausea, throat irritation and congestion. It may also worsen bronchitis, heart disease, emphysema and asthma.

What is an Ozone Action Day?

Ozone Action Days are called by the Ozone Action Partnerships when ground-level ozone is approaching unhealthful levels and the federal standard for ozone is about to be exceeded. On Ozone Action Days, the Partnerships ask the community to take simple, voluntary actions to help reduce ground-level ozone and in turn help prevent an exceedance of the federal standard.

On Ozone Action Days, citizens and businesses are advised to participate in ozone-reducing activities such as: car pool or take mass transit to work, consolidate errands, refuel vehicles carefully by not topping off the gas tank, postpone mowing the lawn until later in the evening, and use latex instead of oil-based paint.