Ozone health effects

The main environmental issue concerned with VOCs is their ability to form low-level ozone and smog through free radical air oxidation processes. The EPA has published a list detailing a number of adverse health effects, which are now thought to originate from the presence of VOCs in the environment, including ... 

In a clean troposphere, ozone would react with NO molecules, resulting in no net generation of ozone. However, in a dirty atmosphere, excess ozone is generated, thereby resulting in the formation of an oxidant which can lead to health effects, an especially hazardous condition for children and the elders who suffer from asthma and other respiratory challenges. 

The most important health effects, in terms of economic damages that can be assigned monetary values, are premature mortality and increased incidence of chronic heart and lung disease. The air pollutants that have shown the strongest association with premature mortality and heart and lung disease are PM and airborne lead. PM has also been associated with hospital admissions, respiratory infections, and asthma attacks. Ozone has also been associated with mortality, hospital admissions, asthma attacks and respiratory restricted activity days (RADs), days on which a person cuts back on his or her normal activities, but does not necessarily miss work or stay in bed. S02 and NOx do not have such significant direct effects, though they do have... 

Convincing new information on the health effects of oxidant exposure has emerged from controlled studies on humans, from which tentative dose-response curves have been constructed. These data are reviewed in Chapter 9, with the types of experimental facilities now available for such measurements. The new data show reduced pulmonary function in healthy smokers and nonsmokers after exposure to ozone at 0.37 ppm and higher for 2 h. The federal standard is 0.08 ppm for a I-h exposure.) Other gases and aerosols found in an urban atmosphere were not present in these experiments. 

The use of ozonizers for deodorizing indoor air has been discussed and evaluated with respect to potential health hazards. In a normal 40-m room, an ozone concentration of 0.1 ppm is established after 3.5 h of operation of one of these devices. Evidence on health effects was cited to support the conclusion that inhalation of the quantities of ozone produced by these air conditioners should be avoided and that certainly no beneficial effects should be attributed to ozone inhalation. 

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. 

Hackney, J. D., W. S. Unn, D. C. Uw. S. K. Karuza, H. Greenberg, R. D. Buckley, and E. E. Pedersen. Experimental studies on human health effects of air pollutants. III. Two-hour exposure to ozone alone and in combiiuition with other pollutant gases. Arch. Environ. Health 30 385-390, 1975. 

During controlled exposures of human subjects to specific compounds like ozone, the concentrations of suspended particles and trace gases must be known and minimized to ensure that health effects can be attributed solely to ozone. The air purification units for the environmental chambers are designed to remove most of the particles and pollutant gases from the ambient air. Prefilters and efficient absolute filters are used to remove 99% of the particles with diameters of 0.3 nin... 

The data base on health effects of photochemical oxidants and ozone was reviewed by the Subcommittee on Ozone and Other Photochemical Oxidants in a report prepared in September 1974 for the Committee on Public Works, U.S. Senate.The following discussion repeats some of the material in that report, to exemplify the need for further work, including controlled human studies. 

The newer experimental studies described above - - - show that significant adverse health effects occur in humans at ozone concentrations of 0.37 ppm and higher. Some limited studies show... 

Closing volume measurement, 29S-96 Colorimetric analysis for air monhoriqg, 262-64,27S to measure nitrogen oxides, 269 Community Health Effects Surveillance Studies (chess), 9,432 Concentration. See Ozone otmcentration Feroi aoetyliiitrate concentration Photochemical-oxidant concentration... 

Difunctional oxygenated organic compounds health effects of, 4 volatility of, 86 Diolefins, 57-58,60 aerosols from, 4, 70-72,83, 88.675 in automotive exhahst, 101 DNA (deoxyribonudeic add), effect of ozone exposure on, 351-52, 363 Dose-response relationship, for exposure to ozone... 

The interplay of HO, peroxy radicals, VOCs, and NO , species has substantial implications for tropospheric air quality. For instance, VOCs, NO , , and sunlight result in poor visibility from ozone and aerosol formation, together denoted as photochemical smog, which can lead to adverse health effects in sensitive individuals. Normally, we think of minimizing either class of compounds as beneficial to the atmosphere. However, minimizing VOC emissions only impacts ozone concentration in high-NO , areas. Moreover, in VOC-sensitive areas, reductions in NO , may lead to the overproduction of ozone. We can examine a simplified scheme for ozone production ... 

As discussed in detail in Chapters 6 and 16, organic compounds play a key role in the formation of ozone, particles, and other species of interest. While some of the individual species are of concern from the point of view of health effects (e.g., the carcinogens benzene and 1,3-butadiene), for most VOC it is because of their... 

Measured total column ozone has fallen between about 1970 and 1994. Ultraviolet irradiation increases at the surface of the earth due to ozone depletion should peak at about 15% in midlatitudes. The incidence of harmful health effects of UV radiation can be expected to rise, eventually, at midlatitudes. Public health action is still necessary to reduce sun exposure, increase protection against the sun, and develop clear policies on the action that should be taken on early detection and treatment of skin cancers (Armstrong, 1997). 

You also increase the adsorbable organic chlorine (AOC1), which is difficult to remove, even by ozone and by bank filtration. Thus, quite a bit of unidentified polar compounds is introduced into drinking water, which you can measure with AOC1 and which could have some health effect, and that is the reason why we avoid chlorination even before bank filtration. 

In order to evaluate the toxicity of ozonation byproducts, the health effects of specific, unidentified substances (byproducts) need to be determined for each target organism (human, animals, fish, etc). The often observed lack of substantial information on toxicity can in part be attributed to the lack of appropriate testing methods. Since identifying all the substances which compose the TOC of a ground-, drinking- or waste water can rarely be... 

The chemistry of ozone in aqueous solutions and the health effects are complex. It is clear that ozone reacts with water products in the water supply to form numerous disinfection byproducts. However, the general pattern that emerges from most studies is that the reaction byproducts of ozonation appear to be less toxic than those produced by chlorination. 

Decreases in nitrogen oxide emissions are also expected to have positive health effects by reducing the nitrate component of inhalable particulates and reducing the nitrogen oxides available to react with volatile organic compounds (VOCs) and form ozone. Ozone impacts on human health include a number of morbidity and mortality risks associated with lung disorders. 

---