So, what is ozone? Basically, it is Oxygen (O2) with and extra atom of oxygen (O). So, O2 + O = O3, or ozone. This extra oxygen atom is what causes all of the excitement. It is like when mild mannered Clark Kent (played by O2) turns into Superman (O3) or when things go wrong Dr. Jekyll (O2)turns into Mr. Hyde.
Whether ozone is good, bad or beautiful depends on where it is in the environment and how much of it is present. Ozone in the stratosphere, a part of the atmosphere that is between 6 and 31 miles above the surface of the earth is the residence of good ozone. Here the ozone shields the earth from harmful UV rays. When ozone is missing we say that there is a "hole" in the ozone layer. This hole allows harmful UV rays to reach plants and people potentially causing harm such as skin cancer.
Ozone in the upper atmosphere is formed naturally by the intense sun light present there. It can be destroyed by certain man made chemicals. A worldwide treaty to ban some of these chemicals was put into place to try and preserve this natural defense against the harmful portion of the sun radiation.
When ozone is at ground level in high concentrations it is bad for people and plants. In fact, ozone in this part of the environment is the most widespread air quality problem in the US effecting people in 100 major cities. Ozone causes damage to vegetation and creates breathing problems for people and animals. The people most affected by ozone are children, those with lung problems and active adults that spend time outside exercising.
Ground level ozone is formed naturally at very low concentrations, but the large amounts of ozone in the environment at ground level are due to the interaction of sunlight with man made chemicals. These chemicals come from the exhaust of cars and power plants. In addition, some chemical compounds like gasoline evaporate during the process of fueling our cars at a gas station. This evaporated gasoline can also react with sunlight to form bad ozone. Various measures have been taken to minimize the formation of bad ozone, for example the special devices on the hoses at the gas pump to collect the evaporated gasoline. Nonetheless, many major cities still can't meet the clean air standards for controlling ozone levels.
There is another kind of "good" ozone. This is man made ozone used to improve the environment. For more than 100 years in Europe ozone has been used to treat water to remove chemical pollutants and kill dangerous micro organisms in drinking water. In the last 30 years, ozone use in US for treating drinking water has grown substantially such that many major cities have at least part of their water treated in this fashion. These cities include Los Angeles, Boston, Orlando, Atlanta, Detroit, Dallas, and Orlando.
Ozone for water treatment is produced in an ozone generator that uses electricity to convert oxygen to ozone. The ozone is mixed with water where it dissolves and attacks chemicals and bacteria cleaning the water. After ozone has done with its work, it turns back into oxygen. Besides making water safer to drink, ozone also improves the taste, odor and appearance of drinking water. Today, almost all bottled water is treated with ozone. As a result, most people have benefit from this "good" ozone without even realizing it. Beyond drinking water, ozone is used to remediate polluted ground water or clean industrial wastewater before it enters the environment.
So, the next time you hear about ozone in the news, you will know that there is more to the story than the ozone layer or the daily smog forecast. Ozone is also an important technology for protecting the water we all need.
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