What is Ozone?
Ozone is a gas found both in the Earth’s upper atmosphere and at ground level, where its effects differ significantly depending on its location.
- Stratospheric Ozone: High up in the atmosphere, ozone serves an important purpose: it protects us from the sun’s ultraviolet radiation. Found naturally in the upper atmosphere, stratospheric ozone forms a protective layer that shields life on Earth from the sun’s harmful ultraviolet (UV) rays. This “good” ozone has been partially depleted by manmade chemicals, creating what is often referred to as the “ozone hole.” However, due to efforts to reduce harmful emissions, this hole is gradually shrinking.
- Ground-Level Ozone: Unlike its stratospheric counterpart, ozone at ground level is a harmful air pollutant. Ozone pollution is toxic to people, irritating our throats and lungs, making it difficult to breathe, increasing our susceptibility to respiratory infections, and exacerbating ailments such as asthma. It also poses risks plants, animals, and the environment, and is a key component of smog.
Another type of air pollution in Colorado is particulate matter, (also called particle pollution) and referred to as PM 2.5 or PM 10, based on the size of the particles causing the pollution. You can learn more about Particle Pollution on EPA’s website. Particulate matter is one of EPA’s recognized criteria air pollutants, and is monitored throughout the Pikes Peak Region. This is also found in wildfire smoke, is harmful to breathe, and can make ozone pollution even worse. However, both colorless and odorless, ozone is different than wildfire smoke and PM2.5.
How Does Ground-Level Ozone Form?
Ozone is three oxygen atoms stuck together in a molecule sometimes referred to as “O3.” Ground-level ozone is not emitted directly into the air. Instead, it forms through chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC) in the presence of sunlight.
- Nitrogen Oxides are highly reactive and toxic gases formed by the combustion of fuels, such as from vehicles, power plants, industrial facilities, refineries, and other sources.
- Volatile Organic Compounds are compounds of carbon that participate in photochemical reactions in the atmosphere (ie. reacts under sunglight). These emissions come mainly from our gas-powered vehicles, lawn equipment, and oil and gas production.
Ozone can also be transported long distances by wind. Ozone is most likely to reach unhealthy levels on hot sunny days in urban environments, but can still reach high levels during colder months.
What is background ozone and why is it important?
Background ozone refers to the ozone originating from distant sources. Since air pollution knows no boundaries, background ozone can result from natural processes, such as stratospheric intrusions or wildfires, as well as from pollution transported across international and state borders. Understanding where background ozone forms and how it is transported is crucial for developing successful reduction strategies.
What are the harmful effects of ozone?
You can’t see or smell ground-level ozone, but it’s harmful to breathe, and can have harmful effects on health. Exposure to ozone can lead to symptoms such as coughing, a sore or scratchy throat, and difficulty breathing deeply or vigorously. It may also cause pain when taking a deep breath, inflame and damage the airways, and make the lungs more vulnerable to infections. Ozone exposure can worsen lung conditions like asthma, emphysema, and chronic bronchitis, and may increase the frequency of asthma attacks. While these effects can occur even in healthy individuals, they are more severe in people with existing health challenges or lung diseases, older adults, and children. For more information on the harmful health effects of ozone, see the EPA’s webpage.
Ozone can also harm vegetation and ecosystems, including forests, parks, wildlife refuges, and wilderness areas. When ozone enters plant leaves, it can reduce photosynthesis, slow growth, and increase vulnerability to disease, insect damage, other pollutants, and severe weather. In some cases, ozone exposure can cause visible damage to leaves. These effects on individual plants can disrupt ecosystems by altering plant diversity, habitat quality, and water and nutrient cycles. To learn more about the ecosystem effects of ozone pollution, see the EPA’s webpage here.
Are there economic impacts of ozone pollution?
Ozone pollution and the designation of nonattainment under the National Ambient Air Quality Standards can have significant economic impacts. Nonattainment designation indicates that an area fails to meet federal air quality standards, triggering regulatory requirements, including in additional emission-control requirements, that can affect local industries, businesses, and governments.
Many of the economic impacts of ozone nonattainment stem from its effects on public and environmental health, including increased costs associated with hospitalizations, illnesses, reduced worker productivity, and higher rates of premature deaths. Economic activities may also suffer, with decreased tourism, difficulties attracting new businesses, and limitations on the growth of existing businesses and industries. Furthermore, local governments, businesses, and industries must invest substantial resources in planning, implementing, and enforcing mandatory air quality control measures to meet regulatory standards and improve air quality.
What is being done to reduce ozone pollution?
EPA is the lead agency working to evaluate the information from regional air quality monitors, and periodically “designates” an area as attainment or nonattainment according to national ambient air quality standards. If the air quality in a geographic area meets or does better than the national standard, it is called an attainment area; areas that don’t meet the national standard are called nonattainment areas. States must draft a plan known as a state implementation plan to improve the air quality in nonattainment areas. The plan outlines the measures that nonattainment areas in the state will take to improve air quality.
Although the Pikes Peak Region is not yet designated as a nonattainment area, recent ozone trends indicate that a nonattainment designation is likely. PPACG is actively developing and implementing voluntary programs to reduce ozone pollution throughout the region. More information on actions you can take to help reduce ozone pollution can be found on the Air Quality Resources and Programs page.