Health and Environmental Effects
Ozone in the air we breathe can harm our health -- typically on hot, sunny days when ozone can reach unhealthy levels. Ozone can also be transported long distances by wind. For this reason, even rural areas can experience high ozone levels.
Even relatively low levels of ozone can cause health effects. Children, older adults, people with lung disease, and those who are active outdoors may be particularly sensitive to ozone. Children are at greatest risk from exposure to ozone because their lungs are still developing and they are more likely to be active outdoors when ozone levels are high, which increases their exposure. Children are also more likely than adults to have asthma.
Ground-level ozone can cause the following health effects even at low concentrations:
- Aggravate asthma or other respiratory illnesses such as emphysema, and chronic bronchitis
- Irritate respiratory systems causing coughing and throat irritation
- Inflame and damage cells that line the lungs
- Reduce lung capacity, making it difficult to take deep breaths
- Increase susceptibility to respiratory illnesses
- Increase hospitalizations by aggravating respiratory illnesses
- Continue to damage the lungs even when the symptoms have disappeared
These health issues may lead to increased school absences, medication use, visits to doctors and emergency rooms, and hospital admissions.
Ozone also affects sensitive vegetation and ecosystems; including forests, parks, wildlife refuges, and wilderness areas by making them more susceptible to disease, harsh weather, insects, and other pollution during the growing season.
When sufficient ozone enters the leaves of a plant, it can:
- Interfere with the ability of sensitive plants to produce and store food
- Visibly damage the leaves of trees and other plants, harming the appearance of vegetation in urban areas, national parks, and recreation areas
Ozone inhibits the ability of plants to open the microscopic pores on their leaves to breathe. It interferes with the photosynthesis process by reducing the amount of carbon dioxide the plants can process and release as oxygen. These effects can also have adverse impacts on ecosystems, including loss of species diversity and changes to habitat quality and water and nutrient cycles. Elevated levels of ozone lead to reduced agricultural crop and commercial forest yields and reduced growth and survivability of tree seedlings.