Ground-level ozone forms when pollutants from cars and trucks, power plants, factories, and other sources come in contact with each other in heat and sunlight.

Factors such as weather conditions and intensity of sunlight also play a part in how ground-level ozone is formed. Ground-level ozone is one of the biggest parts of smog, and it is usually worse in the summer months.

Air quality measures for Ground Level Ozone are based on the National Ambient Air Quality Standards (NAAQS). The daily NAAQS for Ozone is 0.070 parts per million (ppm). Prior to 2016, the standard was 0.075 ppm.

Measure Description:

  1. Number of days with ozone levels over the daily NAAQS
  2. Number of person-days with ozone levels over the daily NAAQS

View data visualization