Ozone is a colorless gas familiar in its presence around copying machines, sparking motors and other areas where electrical discharge and ultraviolet lights are being used. There is much discussion about the ozone layer near the top of the atmosphere. This ozone is produced by a photochemical reaction between the intense ultraviolet radiation of the sun and the oxygen in the atmosphere. Ozone's presence in the lower atmosphere is unique. Tires and rubber goods, sold in sunny California, have larger amounts of antizonants in them than in less sunny locations. Aircraft flying over northern latitudes have special installations in them, such as an activated carbon bed in the air intake, to capture excess ozone. Ozone is a powerful oxidant, whose oxidizing power is exceeded only by fluorine, hydroxyl radical and atomic oxygen. Ozone's composition is that of three oxygen atoms and is inherently unstable. At a neutral Ph, for instance, the half life of ozone in distilled water at room temperature is 1000 seconds. That means that one-half of the ozone present originally will have decomposed in that time. Applications for ozone use are potable water purification, odor control, waste water treatment including cyanide waste destruction, high purity water production, cooling tower water treatment, mining ore treatment and chemical synthesis. Ozone can be toxic to life. The level at which most people can detect ozone is .01 PPM in air. At these levels its odor is similar to that of new-mown hay. The maximum allowable exposure for an 8-hour period is 0.1 PPM. The symptoms experienced when exposed to ozone at 0.1-1 PPM are headache, throat dryness, irritation of the respiratory passages and burning of the eyes. Once ozone escapes into the atmosphere, its rate of decomposition is much less than when dissolved in water. Engineering considerations must be taken into account for high volumes or concentrations of spent ozone. Destruction of ozone, if necessary, is straight forward and with a number of options, such as thermal and chemical treatments.

Author: Larry Diamond