What is Ozone?
Ozone is in the Earth's upper atmosphere and at ground level. Ozone can be "bad" or "good" for your health and the environment, depending on the location in the atmosphere. Ozone chemically is the same, O3, no matter where it is found, high or low. The location of ozone is in the atmosphere dictates how it relates to the environment and determines its effects on human and ecosystem health.
Ozone is the main catylist in the air pollution and when it combines with hydrocarbons we often refer to the chemical reaction as “smog” or “haze”. Ozone, as a precursor to smog, is highly reactive with sunlight, and in high concentrations near ground level, can be quite harmful to human health. Ozone in the upper atmosphere is beneficial because it blocks the sun’s harmful ultraviolet rays. Protecting the environment is done by reducing ground level ozone, the precursor to smog, and preserving protective ozone in the upper atmosphere.
Ozone occurs in two layers of the atmosphere, the troposphere and the
stratosphere. It is the natural substance to which man-made pollution “clings” . The protective nature of ozone is turned against us when we introduce unnatural pollutants.
The layer closest to the Earth's surface is called the troposphere. Here, ground-level or "bad" ozone creates an air pollutant that is harmful to breathe. This pollutant is called smog and it damages trees, crops and other vegetation. Smog is not decreasing. The presence of smog is causing concern among people. Ozone is not emitted directly into the atmosphere as are carbon monoxide, sulfur dioxide, nitrogen oxides, volatile organic compounds.
The troposphere generally extends to a level about 6 miles up, where it meets the second layer, the stratosphere.
In the stratosphere the "good" ozone layer extends upward from about 6 to 30 miles and protects life on Earth from the sun's harmful ultraviolet (UV) rays. Excessive exposure from these UV rays can cause genetic damage and as a result can cause problems such as skin cancer. Ozone in the stratosphere occurs naturally and acts as a shield, absorbing ultraviolet radiation that could harm life on Earth. This “good” ozone layer is thinning due to man-made pollutants. Cold weather at the Earth's poles exacerbates the thinning of this protective ozone. Evidence of increased skin cancer rates suggests that more UV radiation is reaching the ground. Increased exposure to UV radiation may affect other animals and plants.
Ozone, as an air pollution problem, becomes an issue when the “Good” ozone that is produced naturally in the stratosphere is gradually being destroyed by man-made chemicals referred to as ozone-depleting substances (ODS).
ODS substances were formerly used and sometimes still are used in coolants, foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants. Once released into the air, these ozone-depleting substances degrade very slowly. They can remain in the atmosphere for years as they move through the lower part of the atmosphere until they reach the higher area of the atmosphere.
Even though ODS use is less, past use can still affect the protective ozone layer. Research indicates that depletion of the "good" ozone layer is being reduced worldwide. Thinning of the protective ozone layer can be observed using satellite measurements, particularly over the Polar Regions.
Again, ozone is not always bad. Ozone in the proper applications is one of the most beneficial chemicals generated by man. Commercial applications of ozone include, use as a disinfectant, the bleaching of pulp in paper mills, home air purification and the purification of water. Ozone is also used as chlorine (carcinogenic) substitute and has been used successfully for over 100 years. Manufacturers produce ozone by passing air through an electrical discharge and directing its use.
Where does Ozone Come From?
Ozone is not emitted directly from pollution sources. Instead, ozone is formed in the atmosphere through chemical reactions between gasses in the presence of sunlight.Ozone levels are usually highest on hot, windless summer afternoons, especially in inland valleys. The main sources of hydrocarbons are motor vehicles and evaporation of solvents, fuels and other petroleum products. The main sources of nitrogen oxides are motor vehicles and combustion.
Ozone is called a secondary pollutant because its formation is due to having other chemicals present in the atmosphere. The two pollutants that react to form ozone at ground level are nitrogen oxides (NOx) and volatile organic compounds (VOCs). Nitrogen oxides form from the burning of oil, natural gas, coal or wood. Forest fires and electrical storms produce NOx, but are minor additions to the total. Automobiles are another large source of NOx. Winds can carry NOx emissions hundreds of miles away from their original source.
Volatile organic compounds (VOCs) come from petroleum products and similar organic compounds. Evaporation of gasoline, solvents and oil based paints release VOCs into the air.
Industrial and commercial processes are another source of VOCs while motor vehicles also produce VOCs. Natural sources, for example certain types of vegetation, also discharge VOCs.
The formation of ozone is a complex reaction requiring NOx, VOCs, and sunlight. It tends to form later in the day when sunlight has a chance to ‘cook’ the ingredients. Ground level ozone is referred to as photochemical smog because light and precursor chemicals are required to create O3.
How can Ozone affect my family and community?
Plans to reduce ozone levels aim to reduce emissions of the pollutants that form smog: hydrocarbons and nitrogen oxides. These plans usually include some form of control measures.
Stationary source control measures reduce emissions from industrial and commercial facilities. Stationary sources range in size from large facilities like oil refineries, electronics manufacturing plants, and power plants to smaller facilities such as gasoline stations and print shops. Usually, control on these sources are enforced through tribal permits, inspections or other enforcement actions. An example could be a tribal ordinance that requires any one doing local auto repair and maintenance on native lands to switch from oil-based cleaners to (lower polluting) water-based cleaners.
Mobile source control measures reduce emissions from vehicle engines, such as cars, trucks and buses (on-road mobile sources) or boats, aircraft, trains, snow-gos and ATV, and construction equipment (off-road mobile sources).
What can I to do to decrease ground level Ozone or smog exposure in my community and at home?
Ground level ozone quickly reacts with lung tissue and other organs, and inhaling it causes tissue damage. This not only happens to people but also to animals breathing the air.When smog forms at ground-level it can be harmful to health. Smog can inflame and damage the lining of the lungs like a sunburn on the skin. Smog damages cells which line the air spaces in the lung. Within a few days, the damaged cells are replaced and the old cells are shed, much as skin peels after sunburn. Repeated damage may change the lung tissue permanently.
Smog can also aggravate bronchitis, heart disease, emphysema and asthma; lead to hospital admissions and emergency room visits; impair the body’s immune system defenses, making people more susceptible to respiratory illnesses, including bronchitis and pneumonia. Children, people who work outdoors or exercise outdoors regularly, the elderly, and individuals with pre-existing respiratory problems are most at risk. People who work or exercise outside regularly, the elderly, and individuals with pre-existing respiratory problems are most at risk.
Smog and its components enter plants through the leaves, just like other gases. It can cause visible leaf injury, reduced photosynthetic capacity, increased respiration, premature leaf death, and even mortality. It also can distress reproduction and growth of some plants.
Smog formation and exposure in Alaskan communities is not as significant as in warmer states, but if temperatures rise, as they can do in interior Alaska, you may want to do take the following precautions to help. If you have a refrigerator you may want to make sure they are disposed of property and you can substitute "pump sprays" for aerosol can products.
If you live in a tree covered area remember that trees store carbon during photosynthesis and can remove 50 pounds of carbon in a year.
Haze and smog cause visual impairment and can disrupt the ability to tell what the weather will do or to see tribal sites or sacred grounds.
“When we walk upon Mother Earth, we always plant our feet carefully because we know the faces of our future generations are looking up at us from beneath the ground. We never forget them." Oren Lyons, Onondaga Nation