Ground-level ozone isn’t the same as the protective ozone layer high in the atmosphere. At the surface, ozone is a harmful air pollutant formed when vehicle and industrial chemical emissions react in sunlight. 

When Do Alerts Happen?

EPC issues alerts when air quality is likely to reach unhealthy levels.

Florida’s climate plays a major role in ground level ozone formation. Strong sunlight, warm temperatures, and high humidity create ideal conditions for ozone to form when emissions from vehicles, fuel vapors, and industrial activities are present. Even on days with normal traffic levels, these conditions can allow ozone concentrations to rise quickly, particularly in urban and suburban areas with heavy vehicle use. Ground ozone levels typically rise during late spring through early fall, especially in the afternoon hours (12 PM–6 PM) when sunlight is strongest. EPC issues alerts when air quality is likely to reach unhealthy levels.

What is AQI and Who Publishes It?

The Air Quality Index (AQI) is a standardized scale from 0 to 500 that measures air pollution levels and their health impact:

The AQI is calculated and published by the Environmental Protection Agency (EPA) using data from local and state air quality monitoring stations. Air quality professionals analyze weather patterns, atmospheric stability, sunlight intensity, and emission trends to predict when ozone levels are likely to reach unhealthy ranges. These alerts are designed to provide advance notice so residents can take precautions before exposure occurs, rather than reacting after air quality has already worsened. Local agencies such as the EPC issue alerts using monitoring data and predictive tools in coordination with the EPA and the Florida Department of Environmental Protection.

Health Dangers of Ground Level Ozone

Children, older adults, and those with respiratory ailments are most at risk.

Areas near major roadways or with higher traffic density often experience higher ground level ozone level. Sensitive groups like children, older adults, outdoor workers, and individuals with limited access to indoor spaces are especially vulnerable during ozone alerts. Understanding where and why ozone impacts occur helps communities better plan protective measures and long-term air quality improvements.

Exposure to ground-level ozone can cause a range of health problems, especially for the aforementioned sensitive groups:

• Irritates lungs and airways
• Triggers asthma attacks
• Worsens chronic respiratory conditions

How to Protect Your Health and Help Reduce Ozone Formation

• Stay indoors if possible
• Limit outdoor activity during peak afternoon hours

In addition to protecting personal health, small changes in daily habits can help reduce ground level ozone formation during alert days. These include:

• Limiting vehicle use when possible
• Refueling vehicles in the evening rather than midday
• Avoiding the use of gas-powered lawn equipment during peak afternoon hours 

These actions can reduce the emissions that contribute to ozone formation. These actions are most effective when taken collectively during high-ozone conditions.

Ozone alerts are not meant to cause alarm, but to encourage awareness and prevention. By understanding how ozone forms, who is most affected, and what actions can help reduce exposure and emissions, residents can play a role in protecting both public health and local air quality.

Stay informed by checking EPC’s Air Monitoring page or signing up for alerts at: https://www.epchc.org/i-want-to/e-notify

Additional information regarding Ground-Level Ozone can be found at: https://www.epa.gov/ground-level-ozone-pollution