Vermont Forest Indicators Dashboard

Ozone Exposure

Score for 2018:
Long-Term Trend:
Scores are 
Ground-level ozone is formed through a chemical reaction between air-born organic compounds (VOCs) and nitrogen oxides (NOx) when exposed to sunlight1. Ozone pollution can harm forests by causing reductions in photosynthesis, growth, and overall health. Foliar damage due to ozone exposure is the first visible sign of injury, and indicates impaired physiological processes in the leaves1. For some trees, ozone exposure can increase the likelihood of secondary stressors, like damage caused by diseases, insects, or weather events. Ozone is expressed as the average concentration (in parts per million) between the hours of 1:00 and 7:00 pm2. Due to regulations, ground-level ozone pollution has improved gradually over the past decade. Here, we use annual ozone concentration to give us a sense the potential exposure forests may have experienced. The target ozone concentration has been set by the EPA at 0.07 ppm-hour2.
1US EPA. 2013. Integrated science assessment for ozone and related photochemical oxidants. EPA 600/R-10/076F.
2US EPA. 2015. 2015 National Ambient Air Quality Standards (NAAQS) for Ozone. Available at