| Several manufacturers are currently selling ozone | | | | shows that at concentrations that do not exceed |
| generators as air cleaners. The companies | | | | public health standards, ozone has little potential to |
| manufacturing these devices state they are safe | | | | remove indoor air contaminants, though it still has |
| and effective at controlling indoor air pollution; | | | | the longterm potential to cause lung irritation. |
| however, for almost a century health | | | | Vendors claim that ozone will render almost every |
| professionals and health organizations such as the | | | | chemical contaminant harmless through a chemical |
| American Lung Association have challenged these | | | | reaction whose only by-products are carbon |
| claims. | | | | dioxide, oxygen and water. This is false |
| Sellers of ozone-producing devices often use | | | | advertising for several reasons. |
| fanciful terms to describe ozone. It is referred to | | | | First, it takes months to years for ozone to react |
| in such terms as "activated oxygen" or "pure air", | | | | with many of the chemicals commonly found in |
| which suggest that ozone is merely a healthy kind | | | | indoor air (Boeniger, 1995); so for all practical |
| of oxygen. However, ozone is a toxic gas which | | | | purposes, this is useless. Also, ozone generators |
| has vastly different chemical and toxicological | | | | will not remove carbon monoxide (Salls, 1927; |
| properties compared to oxygen. | | | | Shaughnessy et al., 1994) or formaldehyde |
| Ozone is a molecule composed of three atoms of | | | | (Esswein and Boeniger, 1994). |
| oxygen, as opposed to the oxygen we normally | | | | Secondly, in many cases where the reaction |
| breath, which has two. The O2 molecule is stable | | | | between the pollutants and ozone does occur |
| and nonreactive, whereas the O3 molecule is | | | | readily, the by-products are as harmful or irritating |
| unstable, tending to dissociate and produce an O2 | | | | as the original pollutants (Weschler et al., 1992a, |
| molecule and one single ionized oxygen atom. This | | | | 1992b, 1996; Zhang and Lioy, 1994). |
| single atom acts as a "free radicle", that is, it | | | | For instance, a laboratory experiment was |
| reacts with other nearby substances and changes | | | | conducted which mixed ozone with chemicals |
| their chemical composition. It is this ability to | | | | from new carpet. Ozone did reduce many of the |
| combine with other substances that forms the | | | | chemicals, including those which can produce "new |
| basis of manufacturers? claims that it binds up | | | | carpet" odor. However, the reaction produced a |
| organic particles in the air and removes them | | | | variety of aldehydes, and the total concentration |
| from circulation. | | | | of organic chemicals in the air actually increased |
| Unfortunately, the same chemical properties which | | | | (Weschler, et. al., 1992b). Levels of irritating formic |
| allow ozone to react with organic material in the | | | | acid also rise (Zhang and Lioy, 1994). |
| environment also give it the ability to react with | | | | Some of the byproducts of ozone reaction are |
| similar organic material in the body, with potentially | | | | themselves reactive and go on to produce further |
| harmful health consequences. When inhaled, ozone | | | | irritating and corrosive by-products (Weschler and |
| can damage the lungs, and it is considered an | | | | Shields, 1996, 1997a, 1997b). Ozone producing |
| undesirable substance that is a component of | | | | devices turn an indoor environment into a |
| smog. | | | | seething chemical flask. |
| Inhalation of ozone at even low amounts can | | | | Third, ozone by itself does not remove airborne |
| cause respiratory problems and throat irritation. In | | | | particles such as pollen and housedust. However, |
| addition, ozone worsens chronic respiratory | | | | some ozone generators are manufactured with |
| diseases such as asthma and impairs the body's | | | | an "ion generator" or "ionizer" in the same unit to |
| natural ability to fight respiratory infections. | | | | disperse negatively (and/or positively) charged |
| A generally accepted theory of aging states that | | | | ions into the air. These ions attach to particles in |
| the cells of the human body age both due to | | | | the air giving them a negative (or positive) charge |
| genetic factors (loss of cell telomeres) and | | | | so that the particles may attach to nearby |
| oxidative damage by free radicals. People are | | | | surfaces such as walls or furniture, creating an |
| encouraged to eat a diet high in antioxidants, and | | | | undesirable grimy layer; or attach to one another |
| many take antioxidant supplements, precisely to | | | | and settle out of the air. In recent experiments, |
| avoid the kind of damage caused by reactive | | | | ionizers proved ineffective in removing dust, |
| substances such as ozone. | | | | tobacco smoke, pollen or fungal spores compared |
| Most people recover from acute exposure to | | | | to either high efficiency particle filters or |
| ozone, but according to a 1996 EPA study, | | | | electrostatic precipitators. (Shaughnessy et al., |
| long-term exposure may cause permanent lung | | | | 1994; Pierce, et al., 1996). |
| damage. The EPA regards ozone as an air | | | | Even at concentrations that greatly exceed public |
| pollutant and has formulated air quality standards | | | | health standards, ozone is ineffective at cleaning |
| to enable local officials to warn the public when | | | | the air. And unfortunately, there is evidence to |
| ozone levels in urban areas are excessive. When | | | | suggest that in some circumstances ozone |
| ozone (and other air pollutants) are high, | | | | generating devices exceed tolerable output limits. |
| asthmatics and patients with chronic lung disease | | | | Due to the varying brands and models of these |
| are encouraged to stay inside, and healthy people | | | | machines, and the different room sizes in which |
| are told to refrain from strenuous outdoor | | | | they are eventually used, there can be great |
| exercise which raises their breathing rate in the | | | | variation in the eventual concentration of ozone in |
| toxic air. Since people are advised to avoid ozone | | | | the air. |
| in the outdoor environment, it is difficult to | | | | In a study by Shaughnessy and Oatman (1991), a |
| understand why anyone would buy a device to | | | | large ozone generator recommended by the |
| purposely produce it within their own homes. | | | | manufacturer for spaces "up to 3,000 square |
| The FDA requires ozone output of indoor medical | | | | feet," was placed in a 350 square foot room and |
| devices to be less than 0.05 ppm. The | | | | run at a high setting. The ozone in the room |
| Occupational Safety and Health Administration | | | | quickly reached hazardous levels of 0.50 to 0.80 |
| (OSHA) requires that workers' exposure to ozone | | | | ppm, 5-10 times higher than public health limits. |
| not exceed an average concentration of more | | | | In a 1995 EPA study, several different ozone |
| than 0.10 ppm for 8 hours. The National Institute | | | | generators were tested in a home environment, |
| of Occupational Safety And Health (NIOSH) | | | | in rooms of various sizes, with doors alternately |
| recommends an upper limit of 0.10 ppm which | | | | opened and closed, and with the central ventilation |
| should not be exceeded even briefly. EPA?s | | | | system fan alternately turned on and off. The |
| National Ambient Air Quality Standard for ozone is | | | | results showed that some ozone generators, |
| a maximum 8 hour average outdoor | | | | when run at maximum settings in a sealed room, |
| concentration of 0.08 ppm. | | | | frequently produced hazardous concentrations of |
| The EPA coined the phrase "good up high -bad | | | | 0.20 - 0.30 ppm. When the units were run at |
| nearby" to differentiate between ozone in the | | | | lesser settings, with interior doors opened, |
| upper and lower atmosphere. Stratospheric ozone | | | | concentrations generally remained within public |
| in the upper atmosphere about 10 to 50km | | | | health standards. |
| (32,000 to 164,000 feet) above Earth's surface | | | | Due to this wide variation in output and |
| helps filter out damaging ultraviolet solar radiation. | | | | concentration, it is impossible for consumers to |
| This ozone layer is being decimated by CFC | | | | know how much ozone is actually in the air they |
| compounds used in refrigerators and coolant | | | | are breathing; in many ordinary circumstances, |
| systems. After negotiation of an international | | | | ozone generators can produce toxic levels. At |
| treaty, the Montreal Protocol, CFC production was | | | | least one manufacturer is selling machines |
| sharply limited beginning in 1987 and phased out | | | | equipped with ozone sensors that turn the |
| completely by 1996, and a study by the | | | | machine on and off in response to ambient ozone |
| American Geophysical Union shows the rate of | | | | levels, in order to maintain levels of this entirely |
| stratospheric ozone destruction slowing. | | | | undesirable gas within a"safe" range. The EPA is |
| Ozone Generators are ineffective in controlling | | | | currently conducting tests to evaluating the |
| indoor air pollution, because scientific evidence | | | | reliability of these sensors. |