Ozone—Good Up High, Bad Nearby

Ground Level Ozone
Health Effects of Ozone
EPA Releases New Ozone Standard

The word "ozone" has prompted confusion and debate over the past few years. This confusion persists in part because ozone conjures up both good and bad images. In fact, both perceptions are correct. This invisible gas can be found in both the upper and lower atmospheres. The ozone layer in the upper atmosphere exists naturally and is essential to life because it filters harmful ultraviolet radiation from the sun, reducing the amount reaching the earth's surface. High concentrations of ozone near ground level, however, can be harmful to people, animals, crops, and other materials.

Ground Level Ozone
Ground level ozone is the main ingredient in urban and regional smog. Common air pollutants, such as Volatile Organic Compounds (VOCs) and Nitrogen Oxides (NOx), are released from the exhaust of cars, paint, and aerosol products. These pollutants react with heat and sunlight, producing ground level ozone. Unhealthy levels of ground level ozone occur during the summer months, typically May through September.

Each year cars and trucks travel more than 38 billion miles on the roads, accounting for 30-40% of the ozone-causing pollutants. However, motor vehicles are not the only sources of ozone pollution; emissions from lawnmowers, boats, many household products, power plants, and industrial facilities contribute to the formation of ozone.



Health Effects of Ozone
If you are a typical adult, you'll breathe in close to 3,500 gallons of air in a single day. If your atmosphere is ground level ozone-polluted, you may see your lung function reduced by as much as 20 percent.

High concentrations of ozone can cause shortness of breath, coughing, wheezing, fatigue, headaches, nausea, chest pain, and eye and throat irritation. The most common symptom that people have when exposed to ozone while exercising is pain when taking a deep breath.
The EPA estimates that 5 to 20% of the total U.S. population is especially susceptible to the harmful effects of ozone pollution.
The following groups are most vulnerable:
  • Children, because their respiratory systems are still developing. They're more active and spend more time outdoors, inhaling more air pollution per pound of body weight than do adults.
  • People with pre-existing respiratory problems.
  • Athletes and individuals who exercise outdoors.
  • Older adults, because their respiratory and immune systems lose some of their resilience. Damage caused by ground level ozone pollution can aggravate existing conditions or irritate tissues that make them susceptible to infection.
EPA Releases New Ozone Standard
On October 1, 2015, EPA announced a final rule revising the National Ambient Air Quality Standard (NAAQS) for ground-level ozone. The new standard, set at 70 ppb, replaces the ozone standard revision made in 2008 and lowers the Code Orange and above ranges on the Air Quality Index (AQI), EPA’s color-coded tool for communicating daily air quality, in order to better protect public health. more information on the ozone standard