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DAQ Home > Air Pollutants > Ozone

Air Pollutants: Ozone



Ozone is formed when hydrocarbons (also known as volatile organic compounds, or VOC) and nitrogen oxides (NOx) chemically react in the presence of sunlight and heat. Hydrocarbons are emitted from automobiles, gasoline stations, paint, degreasers, cleaning fluids, and many other sources. Plants also give off some reactive hydrocarbons, such as terpenes from pine trees. Nitrogen oxides are emitted by automobiles, power plants, and other combustion processes.

Ozone production is a year-round phenomenon. However, the highest ozone levels occur during the summer when strong sunlight, high temperatures, and stagnant meteorological conditions combine to drive the chemical reactions and trap the air in the region for several days. Ozone produced under these conditions can then be transported many miles outside the urban formation area.

Ground-level ozone should not be confused with the stratospheric ozone layer that is located approximately 15 miles above the earths surface. It is this layer that shields the earth from cancer-causing ultraviolet radiation. Ozone at ground level, where it can be inhaled, is a pollutant, and is known to have harmful effects in both humans and plants. Those most susceptible to harm from ozone are the sick and elderly, newborn and unborn infants, and those with asthma and other chronic lung diseases. Ground level ozone is usually controlled by regulating sources of VOC and NO2. Control strategies include the vehicle inspection and maintenance program and implementation of rules for reasonable, achievable control technologies for industrial sources. Ozone formation can be reduced by voluntary measures such as postponing use of gasoline-powered engines until evening.

Ozone Standard and Emissions Trends

Utah has been in attainment to the federal ozone standard since the early 1990s. In 1997 EPA changed the national ozone standard from a 1-hour standard (0.120 ppm) to an 8-hour standard (0.08 ppm).

For more information contact: Colleen Delaney 801-536-4248