Ozone is not very well understood by the general public. Ozone has been vilified by the press by announcing improperly named “ozone alerts” in some of the larger cities. Ozone, at the concentrations when “ozone alerts” are announced is not a serious threat to human life. The unburned hydro-carbons are the threat, ozone actually destroys the unburned hydro-carbons. If it were not for the ozone, the danger from unburned hydro-carbons to humans would be greater.

It is not unusual to detect ozone in the air at concentrations as high as 0.05 ppm. There are many occupations where workers are exposed to ozone. Excessive concentrations of ozone have been found in many office environments containing electrical equipment such as X-rays apparatus, neon lamps, copy machines, or laser printers. Welders using gas-shielded arc welders have been exposed to ozone concentrations as high as 9.0 ppm, the acute impact subsided when the exposure was reduced to less than 0.2 ppm.

Most agricultural chemicals must be applied at very precise rates, to little and there is no benefit; to much and there is damage to the product or residuals are to high and the product cannot be sold for human consumption. Most of these chemicals build up in the tissue, and over time if exposed to small amounts they could be very harmful or even fatal. Chemical residuals build up in the environment and expensive disposal becomes necessary. Containers used to ship the chemicals and any small amount of chemical left in the container becomes a disposal problem. There is no natural smell to many of the agricultural chemicals and an additive has been added to warn when the chemical is present in the air.

Ozone has none of the above mentioned dangers. A little ozone helps the problem and more works better. Research at O3co has not shown any damage to the product from ozone at concentrations or exposure time many times higher or longer than that recommended. The more ozone the better, it is only of the cost of ozone generating equipment and electricity cost that determines the amount of ozone to apply. Neither the product damage or residual is of any concern, ozone does not harm the product at any application rate you may experience and after it has done the deactivation it reverts back to oxygen and some carbon dioxide. Ozone is generated on site so there are no containers. Ozone has a pleasant smell to most people at safe concentrations, as the concentration increases the smell becomes very objectionable. People would have removed themselves from the ozone because of the odor long before the concentration was high enough to be of serious concern.

1.		As mentioned, ozone is a very powerful oxidizing agent and is produced as a gas. Consequently, there is danger of oxidation of nasal/lung tissues if ozone is breathed. Any damage to body tissues caused by ozone oxidation, however, is a function of time of exposure and gas phase concentrations. Figure 1 shows the relationship between exposure to various concentrations of ozone for periods of time and the corresponding expected effects on human beings (Dimitriou, 1990). Figure 1. Toxicity of ozone to humans (Langewerf, 1963; cited in Dimitriou, 1990) From figure 1 it can be seen that 2.5 ppm (the maximum concentration likely to be encountered in a potato storage or at the discharge of the Ozone Tunnel) would always be in the non-toxic region. It would take about a 70 minute exposure to get beyond the non-toxic region at 10 ppm (a concentration that may occur in the trailer if a leak were to develop). At 500 ppm (treatment concentration in the Ozone Tunnel) it would take about a 7 minute exposure to reach the permanent toxic region. At 2000 ppm (the maximum the controllers allow in the Ozone Tunnel) it would take a 9 minute exposure to get beyond the permanent toxic region. The very pungent smell of ozone at these concentrations would drive anyone out of the ozone in a fraction of these times. This is not to encourage any human exposure to ozone but to point out that the likely hood of any serious effect form ozone around the O3zone Tunnel or in a storage is very remote.
2.		The smell of ozone is pleasant for most people up to about 0.1 ppm. At 2.5 ppm the ozone smell is very nauseating to most. Not many people can stand the smell of ozone at 10 ppm. Normal individuals will quickly remove themselves from excessive exposure long before significant exposures are recorded unless incapacitated or exits or egress is blocked.
3.		Exposure to ozone concentrations up to 0.3 ppm sometimes cause discomfort in a small susceptible portion of the population. Repeated exposure to ozone at such concentrations at 24 hour intervals, however, caused no further increase in the airway irritability. There is no buildup of ozone in the fatty tissue.
4.		There has never been a single recorded fatality attributed to ozone over exposure during more than 100 years of commercial use. The lethal exposure to humans index has been extrapolated from small animal studies.
5.		Upon human exposure, ozone exerts only temporary, acute symptoms. Except in vary rare cases of extended, sever overexposure to high concentrations of ozone (several hours at greater than 2-3 ppm), the physical symptoms of ozone are transitory in nature.
6.		Ozone has a very short half-life, therefore, it must be manufactured on site and immediately used. It cannot be stored. It is produced at low pressures, therefore, an accidental release of large quantities of ozone is not possible. The interruption of the electrical power stops all production of ozone.
7.		Ozone decomposes into simple diatomic oxygen upon breakdown. It will not form environmentally harmful or persistent compounds upon reaction with pathogens, only oxygen and carbon dioxide.

The O3Zone Tunnel is made from the customers portable conveyor, 30,” 36” or 42.” O3Co. furnishes a cover composed of sections that are clamped on the conveyor and sealed with foam sealing strips and the joints are calked. The ozone is contained in the tunnel with an air lock system on each end of the tunnel composed of two sets of special brushes spaced 18” apart. The brushes are free to follow the irregular shape of the top of the potatoes on the conveyor. Ozone that leaks passed the first set of brushes is trapped between the two sets of brushes. A slight vacuum is maintained between the brush sets on the discharge end by the off gas blower. The off gas blower system removes any ozone that leaks past the first set of brushes and discharges it either into the storage air plenum then into the potato pile, or away from any people. Ozone is sometimes carried out of the air lock between the potatoes and the ozone concentration downstream near the conveyors may reach or exceed the maximum recommended OSHA concentration in the work place of 0.10 ppm. An ozone sensor is placed downstream so it will sense and signal when ozone has reached concentrations above the OSHA safe standard where people are working. When this condition occurs, a blower on the discharge end is turned on and remains on until the ozone concentration has dropped below the OSHA standard.

The ozone concentration is monitored in the tunnel, and when the concentration reaches a set point slightly above the desired operating concentration, the CT2000 controller begins shutting chambers down. The automatic shut down continues until the concentration drops to the selected operating concentration or all chambers are off. When the ozone concentration drops below the lower set point, all chambers are turned back on.

Each O3Zone Tunnel system is supplied with a hand held ozone monitor soothe ozone concentrations can be monitored where people work. Corrective action can be taken that will ensure safe ozone concentrations exist where people work. The only location on an O3Zone Tunnel system where ozone concentrations have been observed above the OSHA safe concentration of 0.10 ppm is immediately after the discharge from the tunnel. Ozone concentrations above 0.10 ppm have never been observed beyond 20’ of the tunnel discharge.

In the event ozone concentrations above 0.10 ppm are observed in the storage, a ventilation fan can be turned on for a short time to clear the ozone from the storage where people are working.

The electrical power to the ozone generator can be turned off in an emergency with the main disconnect outside the trailer in the unlikely even large concentrations of ozone occur.

A portable ozone monitor (Porta Sense) is supplied with each system. It is recommended that ozone concentrations are monitored where people are working. If the ozone concentration becomes higher than the maximum OSHA safe level of 0.10 ppm, corrective action should be taken: 1) Move the people to a work station where ozone concentration are safe. 2) Place fans so the ozone can be blown away from the people. 3) Under extreme conditions, shut off the ozone generator.