Friday, December 11, 2009

Ozone

OzonoOzone (O3) is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic O2. Ground-level ozone is an air pollutant with harmful effects on the respiratory systems of animals. The ozone layer in the upper atmosphere filters potentially damaging ultraviolet light from reaching the Earth's surface. It is present in low concentrations throughout the Earth's atmosphere. It has many industrial and consumer applications.


Discovery

Ozone, the first allotrope of a chemical element to be recognized by science, was proposed as a distinct chemical compound by Christian Friedrich Schönbein in 1840, who named it after the Greek verb ozein (ὄζειν, "to smell"), from the peculiar odor in lightning storms. The formula for ozone, O3, was not determined until 1865 by Jacques-Louis Sore and confirmed by Schönbein in 1867.

Applications

The largest use of ozone is in the preparation of pharmaceuticals, synthetic lubricants, as well as many other commercially useful organic compounds, where it is used to sever carbon-carbon bonds. It can also be used for bleaching substances and for killing microorganisms in air and water sources. Many municipal drinking water systems kill bacteria with ozone instead of the more common chlorine. Ozone has a very high oxidation potential. Ozone does not form organochlorine compounds, nor does it remain in the water after treatment. The Safe Drinking Water Act mandate that these systems introduce an amount of chlorine to maintain a minimum of 0.2 ppm residual Free Chlorine in the pipes, based on results of regular testing. Where electrical power is abundant, ozone is a cost-effective method of treating water, since it is produced on demand and does not require transportation and storage of hazardous chemicals. Once it has decayed, it leaves no taste or odor in drinking water.
Although low levels of ozone have been advertised to be of some disinfectant use in residential homes, the concentration of ozone in dry air required to have a rapid, substantial effect on airborne pathogens exceeds safe levels recommended by the U.S. Occupational Safety and Health Administration and Environmental Protection Agency. Humidity control can vastly improve both the killing power of the ozone and the rate at which it decays back to oxygen (more humidity allows more effectiveness). Spore forms of most pathogens are very tolerant of atmospheric ozone in concentrations where asthma patients start to have issues.

Medical Ozone

With regards to the debate of the merits of ozone therapy, the promotional claims by some marketers of ozone generators that it is a miraculous cure for all disease including cancer and AIDS have given many people false hope and hurt the credibility of ozone therapy. Leading the opposing argument is the US Food and Drug Administration who state that ozone is a toxic gas with no known useful medical application in specific, adjunctive, or preventive therapy and in order for ozone to be effective as a germicide, it must be present in a concentration far greater than that which can be safely tolerated by man and animals. The FDA recently approved ozone’s use as a disinfectant in the food processing industry, however.
Neither the Journal of the American Medical Association (JAMA) nor the Geneva-based World Health Organization (WHO) have published any research reporting benefits of ozone use in medicine. However in international peer reviewed medical journals hundreds of articles have been published reporting positive outcomes of medical ozone research and application for a range of pathology. Most of these were published since 1990 and are accessible on medline, and they include pre-clinical studies, animal experiments, patient case histories, placebo-controlled blinded human trials and reviews. The authors are mostly from Italy, Poland, Russia, Germany, Cuba, Spain, Israel, Japan and United States of America, and they draw conclusions that conflict with the FDA. The literature in their native languages is more abundant
Gérard V. Sunnen has made claims that medical use of ozonating blood to kill viruses and bacteria in the blood shows a potential area for scientific research.


External Links