DefinitionThe United States' Environmental Protection Agency (EPA) ozone standard states that the 8-hour average ozone level should not exceed 0.070 ppm. These standard levels are often referred to as the National Ambient Air Quality Standards (NAAQS). This level is considered protective for most people and within the normal defensive capacities of the human respiratory system.^1-3^[[br]]
1. McDonnell, et al. (1997) Prediction of ozone-induced FEV1 changes: Effects of concentration, duration and ventilation. American Journal of Respiratory and Critical Care Medicine. Vol 156, 715-722.[[br]]
2. Mudway, et.al. (2001) Differences in basal airway antioxidant concentrations are not predictive of individual responsiveness to ozone: A comparison of healthy and mild asthmatic subjects. Free Radical Biology and Medicine, Vol 31, No. 8. 962-974.[[br]]
3. Mudway, I and Kelly, F. J. (2004) An investigation of inhaled ozone dose and the magnitude of airway inflammation in healthy adults. American Journal of Respiratory and Critical Care Medicine, Vol 169, 1089-1095.
NumeratorThis Indicator Report contains the following variables:[[br]]
1. Number of days with maximum 8-hour average ozone concentrations above the National Ambient Air Quality Standards (NAAQS) by county[[br]]
2. Number of person-days with maximum 8-hour average ozone concentrations above the NAAQS by county
DenominatorWhen applicable, population was obtained from the IBIS query system for appropriate years by county.
Data Interpretation IssuesData on ozone levels are only available where air monitors exist. These monitors do not cover the entire state. The monitors may not measure ozone levels year-round, as the national standard is to measure mostly during summer months.
These data include "exceptional events" such as high winds, fires, construction, fireworks, etc.
These values represent days when at least one air monitoring station showed a reading over the National Ambient Air Quality Standard (NAAQS) within a county. Each county that had data was used to calculate the percentage of Utah counties that had at least one day where ozone was above the NAAQS. This report uses the 2015 primary and secondary NAAQS of 0.070 parts per million (ppm). For more information on the ozone NAAQS, please visit the [https://www.epa.gov/criteria-air-pollutants/naaqs-table EPA NAAQS Table] and the [https://www.epa.gov/ozone-pollution/table-historical-ozone-national-ambient-air-quality-standards-naaqs Table of Historical Ozone NAAQS]
Data for this report represent ambient air, or outside air quality. The relationship between ambient concentrations and personal exposure can vary significantly depending upon the pollutant, activity patterns, and micro-environments.
Data for this report came from the EPA and therefore may differ slightly from data from other sources.
Why Is This Important?Ozone is a naturally occurring component of the earth's atmosphere at ground level and in the upper regions of the atmosphere. While upper atmospheric ozone protects the earth from the sun's harmful rays, ground-level ozone can be detrimental to the health of plants, animals, and human beings.
Molecules of ozone are made up of three oxygen atoms (O3) and are chemically identical in the upper atmosphere and at ground level. The lungs of animals and humans have a thin liquid lining that protects lung tissue from normal amounts of ozone. However, sunlight and heat can create new ground-level ozone molecules from nitrogen oxides and volatile organic chemicals that are found naturally at the earth's surface, as well as in emissions from industrial facilities, electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents in urbanized regions. Ozone is a principle component of urban smog and is measured in parts per million (ppm).
Ozone can cause several adverse health effects in anyone, but especially in sensitive populations such as children, older adults, people with preexisting lung diseases such as asthma, and people who are physically active outdoors. Some of these health problems include painful breathing, chest tightness, headache, coughing, increased asthma symptoms, lung inflammation, and temporary reduction in lung capacity. Over time, ozone is associated with chronic lung problems and respiratory infections. Adverse health effects from ozone are more likely to occur when ozone levels exceed the EPA's standard, but are possible when ozone levels are below the standard, especially in sensitive populations.
Ground-level ozone, not to be confused with the atmosphere's protective ozone layer, is created by reactions between environmental pollutants, light, and heat. Ozone is the main component of smog and is dangerous to health and the environment. The creation of ozone is facilitated by warm weather and sunshine; therefore, ozone levels are usually higher in the summer and in the mid-afternoon.
Climate change may play a part in the creation of more ground-level ozone pollution. As temperatures increase, it is expected that the number of high ozone days will increase, since heat accelerates the nitrogen oxide and volatile organic compound reaction.^1^ Researchers have found that a combination of higher temperatures, sunlight, emissions, and air stagnation events (i.e., inversions) may result in an increase of ozone levels. However, more research is needed to accurately gauge what portion of ozone is actually increasing solely due to climate change.[[br]]
1. National Aeronautics and Space Administration (2004). The good, the bad and the ozone. Retrieved March 21, 2012 from the National Aeronautics and Space Administration: [http://www.nasa.gov/missions/earth/f-ozone.html]
Other ObjectivesPhysical exercise is essential to maintaining good health. In order to exercise safely, Utahns should refer to daily ozone levels by checking them at [http://www.cleanair.utah.gov]. If ozone levels are high, consider exercising indoors. The best time to exercise outdoors during summer months is before noon or after 6:00 p.m. If outdoor exercise is unavoidable during high ozone levels, consider light to moderate activity such as walking.
How Are We Doing?The most urban counties in Utah often have days that do not comply with the new ozone standard of 0.070 ppm. The Utah Department of Environmental Quality (DEQ) is working to decrease the number of days over the ozone standard.
What Is Being Done?In response to the new EPA ozone standard of 0.070 ppm, DEQ has begun fitting school buses with cleaner technology, and state office buildings have begun adopting more energy-efficient policies and practices.
The DEQ 3-day air quality forecasting program uses a red, yellow, and green stoplight color code to inform the public about how they can help keep pollution levels low and safe. A green day informs the public that pollution levels are low, and they can safely drive and spend time outside. A yellow day informs the public that they should consider limiting driving to reduce pollution levels. A red day strongly encourages the public to reduce driving and other polluting activities to prevent pollution levels from exceeding the health standard.
Ultimately, the air quality for Utah citizens is dependent upon each individual taking steps to reduce the amount of energy used and pollution emitted.