Are Ozone Air Cleaners Safe?

There has been an increase in the topic of ozone generator rental due to the interest in clean air. Some cities are so polluted by smog that there is fear that this bad air is invading homes. Ozone air filters and cleaners are considered to be great air purifiers. Their safety has come into question; however.
So what is in these generators that has some experts in the scientific community up in arms--ozone! Ozone is 3 atoms of oxygen. Over 20 years ago, people became familiar with the term "ozone" due to the hole in the ozone layer in the upper atmosphere of the Earth. The ozone layer filters out the UV light from the sun. The hole was formed by the effects of man-made chemicals called chloroflurocarbons or CFCs which are mostly found in aerosol cans. In 1987 an international treaty, The Montreal Protocol, was signed to protect the layer by wiping out CFCs from production. The hole is on the mend but there is speculation that it is one of the main culprits of global warming.
The "high in the sky" stratospheric ozone is not harmful but ozone near the ground can be toxic if the concentration is high. Potential problems could lead to irritation of the throat lining, coughs, inflamed lungs, asthma and respiratory issues.
The Environmental Protection Agency does not endorse ozone air purification. They advise that the level of ozone used can not be accurately controlled; therefore, no pets or people should be exposed. Also, the agency believes that the ozone could damage plants, rubber casings of electrical wires, fabric and works of art. Furthermore, the EPA cites studies that ozone generators are not good for odor removal. If a citizen rents an ozone generator or buys one, it is done at their own risk.