Effects of Ozone

The effect of ozone is complicated in so far as its effect is largely at or near the surface and is of greatest consequence in lightly stressed rubbers. Cracks are formed with an axis perpendicular to the applied stress and the number of cracks increases with the extent of stress. The greatest effect occurs when there are only a few cracks which grow in size without the interference of neighbouring cracks and this may lead to catastrophic failure. Under static conditions of service the use of hydrocarbon waxes which bloom to the surface because of their crystalline nature give some protection but where dynamic conditions are encountered the saturated hydrocarbon waxes are usually used in conjunction with an antiozonant. To date the most effective of these are secondary alkyl-aryl-p-phenylenediamines such as /V-isopropyl-jV-phenyl-p-phenylenediamine (IPPD). 

By mo ing from a one-hour to an eight-hour measurement, the standtird will better reflect the real-world effects of ozone on human health... 

Although in this chapter we have focused on the potential effects of increased UV-B radiation on the Antarctic marine ecosystem, our results also have bearing on efforts to describe the effects of UV radiation on global marine productivity. However, here again, considerable uncertainties still remain in assessing the effects of ozone depletion on global production. Several authors have predicted a... 

Due to the retractive forces in stretched mbber, the aldehyde and zwitterion fragments are separated at the molecular-relaxation rate. Therefore, the ozonides and peroxides form at sites remote from the initial cleavage, and underlying mbber chains are exposed to ozone. These unstable ozonides and polymeric peroxides cleave to a variety of oxygenated products, such as acids, esters, ketones, and aldehydes, and also expose new mbber chains to the effects of ozone. The net result is that when mbber chains are cleaved, they retract in the direction of the stress and expose underlying unsaturation. Continuation of this process results in the formation of the characteristic ozone cracks. It should be noted that in the case of butadiene mbbers a small amount of cross-linking occurs during ozonation. This is considered to be due to the reaction between the biradical of the carbonyl oxide and the double bonds of the butadiene mbber [47]. 

Effect of ozone pretreatment on low temperature CO oxidation catalysts... 

Titanium dioxide supported gold catalysts exhibit excellent activity for CO oxidation even at temperatures as low as 90 K [1]. The key is the high dispersion of the nanostructured gold particles over the semiconducting Ti02 support. The potential applications of ambient temperature CO oxidation catalysts include air purifier, gas sensor and fuel cell [2]. This work investigates the effects of ozone pretreatment on the performance of Au/Ti02 for CO oxidation. 

Henry, L.K. et al.. Effects of ozone and oxygen on the degradation of carotenoids in an aqueous model system, J. Agric. Food Chem., 48, 5008, 2000. 

Hatch, G.E., Slade, R, Crissman, K., Norwood, J. and Koren, H. (1989). Vitamin E concentrations in bronchoalveolat lavage fluid of humans, rats and guinea-pigs effect of ozone inhalation. Am. Rev. Resp. Dis. 140, A279. 

Matsumara, Y. (1970). The effects of ozone, nitrogen dioxide and sulphur dioxide on the experimentally induced allergic... 

That x-rays render various substances strongly thermo-luminescent has already been shown.1 The following experiments have been made to determine the subsequent effect of ozone upon such materials. 

Perez, A.G., Sanz, C., Rios, J.J., Olias, R. and Olias, J.M. (1999) Effects of ozone treatment on postharvest strawberry quality . Journal of Agricultural and Food Chemistry, 47, 1652-1656. 

Retardation of oxidative degeneration and the effects of ozone attack can be mitigated but not totally overcome by the use of chemicals which, unfortunately, in the case of the most effective types, carry the penalty of causing staining of the rubber compound or surfaces with which it comes into contact. 

Janie, B., et al., Modulatory effects of ozone on THP-1 cells in response to SP-A stimulation, Am. J. Physiol. Lung Cell Mol. Physiol. 288, 2, L317, 2005. 

Matsumura, Y., et al., The effects of ozone, nitrogen dioxide, and sulfur dioxide on experimentally induced allergic respiratory disorder in guinea pigs. IV. Effects on respiratory sensitivity to inhaled acetylcholine, Am. Rev. Respir. Dis. 105, 2, 262, 1972. 

Korai, H., Kiguchi, M., Hosoya, S., Suzuki, S., Hirano, Y. and Iwata, R. (2001). Improvements of fiberboard made from acetylated fibers by ozonation I effect of ozonation on mechanical properties. Journal of Wood Science, 47(1), 24—29. 

This report deals primarily with the origins and effects of ozone and other photochemical oxidants. It is limited, more or less, to the problem of urban pollution and to such closely related topics as natural background in the earth s boundary layer. No consideration is given to the stratospheric ozone layer and the effects produced by supersonic transport (sst) emission or halocarbons. 

Toxicologic research (Chapter 8) on the effects of ozone in laboratory animals has demonstrated that exposure to airborne ozone at less than 1 ppm for a few hours produces numerous changes in cell and organ structure and function. The lowest concentrations that produce these changes differ somewhat among different species of laboratory animals and with the effect under observation. However, several functional and morphologic indexes of response to ozone are altered with exposures to concentrations of about 0.2-0.5 ppm over periods ranging from a few minutes to several weeks. 

The sites of action and effects of ozone and other photochemical oxidants are described in Chapters 8 and 9. Recent work with primates has suggested that ozone is absorbed along the entire respiratory tract, penetrates more into the peripheral nonciliated airways, and causes more lesions in the respiratory bronchioles and alveolar ducts as the inhaled ozone concentration increases from 0.2 to 0.8 ppm. The most common and most severe tissue damage was observed in the respiratory bronchioles. The ciliated cells in the terminal bronchioles and the Type 1 cells in the epithelial layer of the proximal alveoli of rats were the... 

Fairchild and Graham, Stokinger et and Stokinger showed that the toxic effect of ozone in experimental animals is cumulative. They found that the effective dose depends on the product of ozone concentration and exposure duration for short-term single exposures. 

Bates, D., and M. Hazucha. The short-term effects of ozone on the human lung, pp. 507-540. In National Research Council. Assembly of Life Sciences. Proceedings of the Conference on Health Effects of Air Pollutants, October 3-5, 1973. 

In a study of the mechanism whereby BordeteUa pertussis vaccine increased acute ozone toxicity in rats, Thompson ascribed the effects to /3-adrenergic blockade, and not to an immune-mediated response. It was further noted that both atropine and reserpine reduced mortality, whidi suggested that the acute lethal effects of ozone were due to shock and circulatory collapse, rather than pulmonary edema. 

The idea that Ozone toxicity is expressed through the formation of reactive free-radical intermediates was originally derived from studies that noted the similarity of the effects of ozone to those of radiation. Earlier studies... 

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