The Issue

Ozone is a gas that occurs both in the Earth's upper atmosphere and at ground level where it is a key component of urban smog. Ground-level ozone causes a variety of effects on human health, vegetation, and ecosystems and it affects climate. Human exposure to ozone is associated with respiratory and cardiovascular effects as well as premature death. Ozone exposure causes visible foliar injury, decreases plant growth and affects ecosystem community composition.

Peak ozone levels typically occur during hot, dry, stagnant summertime conditions. Millions of Americans live in areas where ozone levels exceed EPA's health-based air quality standards, primarily in parts of the Northeast, the Lake Michigan area, parts of the Southeast, southeastern Texas, and parts of California.

EPA Action

EPA's ozone research efforts are focused on improving emissions estimates, determining health and ecological effects, and improving modeling capabilities. EPA's National Center for Environmental Assessment periodically evaluates the latest research concerning the public health and welfare effects of ozone and publishes the most up-to-date findings in an assessment called an Integrated Science Assessment. This document provides the scientific basis for the establishment of the most current national air quality standards for ozone. EPA released the Integrated Science Assessment for Ozone and Related Photochemical Oxidants Final Report in February 2013.

• Learn about the 2013 Final Report: Integrated Science Assessment for Ozone and Related Photochemical Oxidants
• Learn about the Ozone Air Quality Standards

History of the Ozone Assessments

Peer Reviewed Literature

While working on the assessment of ozone (2012), EPA used the Health and Environmental Research Online (HERO) database to augment the underlining literature that supported the final assessment.

See: ISA-Ozone (2012) HERO Project page