Ozone control strategy

Simpson, D., Biogenic Emissions in Europe. 2 Implications for Ozone Control Strategies, J. Geophys. Res., 100, 22891-22906... 

Sistla, G N. Zhou, W. Hao, J.-Y. Ku, S. T. Rao, R. Bornstein, F. Freedman, and P. Thunis, Effects of Uncertainties in Meteorological Inputs on Urban Airshed Model Predictions and Ozone Control Strategies, Atmos. Environ., 30, 2011-2025 (1996). 

Winner, D. A., G. R. Cass, and R. A. Harley, Effect of Alternative Boundary Conditions on Predicted Ozone Control Strategy Performance A Case Study in the Los Angeles Area, Atmos. Environ., 29, 3451-3464 (1995). 

Wolff, G. T., and P. E. Korsog, Ozone Control Strategies Based on the Ratio of Volatile Organic Compounds to Nitrogen Oxides, J. Air Waste Manage. Assoc., 42, 1173-1177 (1992). 

Ellison, W., Butcher, T. A., Carbonara. J. C.. and Heaphy, J.P., 1994, Heat Recovery and Pollution Cleanup from Low Grade Fuels, Conference on Ozone Control Strategies for the Next Decade (Century), Air and Waste Management Association, San Francisco, CA, April 11-12. 

Although the naturally occurring concentration of ozone at the earth s surface is low, the distribution has been altered by the emission of pollutants, primarily by automobiles but also from industrial sources which lead to the formation of ozone. The strategy for controlling ambient ozone concentrations arising from automobile exhaust emissions is based on the control of hydrocarbons, CO, and NO via catalytic converters. As a result, peak ozone levels in Los Angeles, for instance, have decreased from 0.58 ppm in 1970 to 0.33 ppm in 1990, despite a 66% increase in the number of vehicles. 

The most complete data on ozone and other oxidant concentrations have been obtained for the Los Angeles air basin, because of the severity of the problem there. Further measurements are needed in the central and eastern areas of the United States, to broaden the foundations of a national control strategy. Such studies should be designed with specific goals in mind, and not carried out as routine monitoring exercises. 

Indeed, these reactions play an important role in the Antarctic ozone hole and they have important implications for control strategies, particularly of the bromi-nated compounds. For example, Danilin et al. (1996) examined the effects of ClO -BrO coupling on the cumulative loss of O-, in the Antarctic ozone hole from August 1 until the time of maximum ozone depletion. Increased bromine increased the rate of ozone loss under the denitrified conditions assumed in the calculations by converting CIO to Cl, primarily via reactions (31b) and (31c) (followed by photolysis of BrCl). Danilin et al. (1996) estimate that the efficiency of ozone destruction per bromine atom (a) is 33-55 times that per chlorine atom (the bromine enhancement factor ) under these conditions in the center of the Antarctic polar vortex, a 60 calculated as a global average over all latitudes, seasons, and altitudes (WMO, 1999). 

Because one of the major impacts of increased UV at the earth s surface is expected to be an increase in skin cancer, several countries now include UV forecasts as part of their weather reports (e.g., see Kerr, 1994), and estimates of skin cancer increases due to ozone depletion have been made. Figure 13.20, for example, shows the estimated number of excess cases of skin cancers for the United States and for northwestern Europe if no controls had been imposed on CFCs and halons and those expected with the Copenhagen Amendments (Slaper et al., 1996). Clearly, there is expected to be a major impact of the control strategies on the incidence of skin cancer, although the number of excess cases will still be about 33,000 per year in the United States and 14,000 per year in northwestern Europe at the projected worst-case year of 2050. 

It is clear from the data presented in this chapter that the effects of control strategies developed for CFCs and halons are already measurable. Although loss of stratospheric ozone with accompanying increases in ultraviolet radiation in some locations have clearly occurred, the tropospheric concentrations of CFCs are not increasing nearly as fast as in the past. Indeed, the concentrations of CFC-11 and CFC-113 appear to have peaked and have started to decline. The equivalent effective stratospheric chlorine concentrations are predicted to have peaked about 1997 and to return to levels found around 1980 at about the year 2050 (World Meteorological Organization, 1995). The significance of the 1980 level is that these levels resulted in detectable Antarctic ozone depletion. 

While the tropospheric concentrations of CFCs and halons are not increasing as rapidly in the past due to controls outlined in the Montreal Protocol and subsequent amendments, those of the CFC replacements are increasing. However, due to their different structures and reactivities, the ozone depletion potentials associated with these compounds are significantly less that those of the compounds they replace. This truly represents a success story in terms of application of atmospheric chemistry to the development of effective control strategies. 

Air Pollution Control Strategies and Risk Assessments for Tropospheric Ozone and Associated Photochemical Oxidants, Acids, Particles, and Hazardous Air Pollutants... 

Understanding the chemical and physical processes discussed throughout this book is key to the development of cost-effective and health-protective air pollution control strategies. Application of atmospheric chemistry to reducing stratospheric ozone depletion was discussed in Chapter 13. Here we focus on its key role in strategies for controlling tropospheric pollutants, including ozone, acids, particles, and hazardous air pollutants. 

Developing control strategies for ozone is very different than for relatively unreactive species such as CO. In the latter case, the concentrations in air are a direct result of the emissions, and all things being equal, a reduction in emissions is expected to bring about an approximately proportional reduction in concentrations in ambient air. However, because O, is formed by chemical reactions in air, it does not necessarily respond in a proportional manner to reductions in the precursor emissions. Indeed, as we shall see, one can predict, using urban airshed or simple box models, that under some conditions, ozone levels at a particular... 

The kinetic modeling nomenclature arises from the incorporation of chemical kinetic submodels in EKMA. The empirical term comes from the use of observed 03 peaks in combination with the model-predicted ozone isopleths to develop control strategy options. Thus, the approach historically was to use the model to develop a series of ozone isopleths using conditions specific for that area. The second highest hourly observed 03 concentration and the measured... 

The most direct approach to assessing the effectiveness of a control strategy or strategies would at first glance appear to be an examination of the relationship between reductions in emissions and measured changes in air quality. As discussed in detail in Rethinking the Ozone Problem in Urban and Regional Air Pollution (National Research Council, 1991), this unfortunately has not been possible for a variety of reasons. For example, as discussed earlier, pollutant concentrations... 

It is interesting that over the same period in many other regions of the United States and in Europe and Japan, ozone levels did not appear to change as dramatically (National Research Council, 1991 Lindsay et al., 1989 Rao et al., 1992, 1994, 1995, 1996 Zurbenko et al., 1995 Fiore et al., 1998 Oltmans et al., 1998). The major difference in control strategies in California compared to the U.S. federal approach has been an emphasis on both NO, and VOC control, rather than primarily on VOC as has been the case at the federal level. For example, Table 16.3 shows the more stringent control of both NO, and VOC from motor vehicles in California beginning in the mid-1970s. Since 1980, however, VOC emission standards in California have been comparable to the federal standards while the allowed NO, emissions have been smaller by a factor of two or more. 

Duncan, B. N., and W. L. Chameides, Effects of Urban Emission Control Strategies on the Export of Ozone and Ozone Precursors from the Urban Atmosphere to the Troposphere, J. Geophys. Res., 103, 28159-28179 (1998). 

MacGregor, L and H. Westberg, The Effect of NMOC and Ozone Aloft on Modeled Urban Ozone Production and Control Strategies, J. Air Waste Manage. Assoc., 40, 1372-1377 (1990). 

Sillman S. (1993) Tropospheric ozone the debate over control strategies. Ann. Rev. Energy Environ. 18, 31-56. 

Strategies for the control of photochemical oxidants contain information not only on the extent of both hydrocarbons and NO, controls but their separate locations. Optimisation by simulated annealing has been applied to the investigation of optimal strategies for ozone control, involving the simultaneous abatement of hydrocarbons and NO, emissions in concert. This application involves the following stages ... 

The section 185B study concludes that, based on the latest scientific evidence, the ozone precursor control effort should focus on NOx controls in many areas and that the analysis of NO benefits is best conducted through photochemical grid modeling. This apparent shift, explains the study, coincides with improved data bases and modeling techniques that provide the analytical means to evaluate the effectiveness of ozone precursor control strategies. 

If EPA grants a petition, these Federal NO, requirements will no longer apply. However, States remain free to impose NO, restrictions on other bases. For example. States may choose in certain circumstances to reduce NO, emissions for purposes of ozone maintenance planning, visibility protection, PM-10 control strategy, acid deposition program or other environmental protection. 

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