Ozone impact

Lowi, A. and W.P.L. Carter (1990), A method lor evaluating the atmosphere ozone impact of actual vehicle emissions . SAE paper No. 90-0710, International congress and exposition, Detroit, MI. 

Lloyd, A.C., Atkinson, R., Lurmann, F.W., and Nitta, B. Modeling potential ozone impacts from natural hydrocarbons -1. Development and testing of a chemical mechanism for the NOx-air photooxidations of isoprene and a-pinene under ambient conditions, Atmos. Environ., 17(10) 1931-1950, 1983. 

LT026 Gonzalez-Coloma, A., C. S. Wisdom, and P. W. Rundel. Ozone impact on the antioxidant nordihydroguaiaretic acid content in the external leaf resin of Larrea tridentata. Biochem Syst Ecol... 

Brasseur, G. P., J. T. Kiehl, J.-F. Muller, T. Schneider, C. Granier, X. Tie, and D. Hauglustaine, Past and Future Changes in Global Tropospheric Ozone Impact on Radiative Forcing, Geophys. Res. Lett, 25, 3807-3810 (1998). 

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. 

Many different types of volatile organic compounds (VOCs) are emitted into the atmosphere, where they can affect photochemical ozone formation and other measures of air quality. Because they can react in the atmospheres at different rates and with different mechanisms, the different types of VOCs can vary significantly in their effects on air quality. The effect of a VOC on ozone formation in a particular environment can be measured by its incremental reactivity , which is defined as the amount of additional ozone formed when a small amount of the VOC is added to the environment, divided by the amount added. Although this can be measured in environmental chamber experiments, incremental reactivities in such experiment cannot be assumed to be the same as incremental reactivities in the atmosphere (Carter and Atkinson, 1989 Carter et al, 1995). This is because it is not currently practical to duplicate in an experiment all the environmental factors that affect relative reactivities and, even if it were, the results would only be applicable to a single type of environment. The only practical means to assess atmospheric reactivity, and how it varies among different environments, is to estimate its atmospheric ozone impacts using airshed models. 

The two large open circles on Figure 1 show the ROG and NOx levels chosen to serve as the base case in the incremental reactivity experiments that are currently underway in this chamber to assess ozone impacts of various different types of VOCs (Carter, 2004c). The 25-30 ppb NOx levels were chosen to be representative of pollution episodes of interest in California, based on input provided by the staff of the California Air Resources Board, which is funding most of the current reactivity studies. The ROG/NOx ratios were chosen to represent two sets of conditions of NOx availability relevant to VOC reactivity. The lower ROG/NOx ratio was chosen to represent the relatively higher NOx conditions of maximum incremental reactivity (MIR) where ozone is most sensitive to VOCs, to approximate the conditions used to derive the widely-used MIR ozone reactivity scale (Carter, 1994). The higher ROG/NOx ratio was chosen to be one-half that yielding maximum ozone levels, and is used to represent conditions where ozone is NOx-limited, but not so NOx-limited that VOC reactivity is irrelevant. These are referred to in the subsequent discussion as the MIR and MOIR/2 base eases, respeetively. 

Carter, W. P. L. Main information page for Evaluation of atmospheric ozone impacts of selected coatings VOC emissions and Environmental chamber studies of VOC species in architectural coatings and mobile source emissions , http //www.certucr.edu/ carter/coatings. Last modified April 17. (2004c)... 

Two methods are generally employed to quantify the role pollutants play in forming ozone experimental and eomputational. Both types of estimation approaehes have their limitations. In the case of physical experiments, it is difficult to fully simulate ambient conditions, so the results do not have general applicability. In the case of computational approaches, uncertainties and approximations in the model for airshed conditions, in its formulation, and in the chemical mechanism cause uncertainties in the predicted ozone impacts. For these reasons, modeling predictions and experimental measurements are used together. 

The program s Phase I consists of (a) measuring emissions for a number of fuels and vehicles (b) modelling to predict the ozone impact from these emissions and (c) conducting an economic analysis for the foel/vehicle options to provide a range of potential costs to reach the air quality... 

Pleijel H. Ozone impact on Swedish cereals [dissertation]. Goteborg (Sweden) Goteborg University, 1994. 

Navakoudis E, LUtz C, Langebartels C, Ltitz-Meindl U, Kotzabasis K (2003) Ozone impact on the photosynthetic apparatus and the protective role of polyamines. Biochim Biophys Acta 1621 160-169... 

Ozone can be destroyed thermally, by electron impact, by reaction with oxygen atoms, and by reaction with electronically and vibrationaHy excited oxygen molecules (90). Rate constants for these reactions are given ia References 11 and 93. Processes involving ions such as 0/, 0/, 0 , 0 , and 0/ are of minor importance. The reaction O3 + 0( P) — 2 O2, is exothermic and can contribute significantly to heat evolution. Efftcientiy cooled ozone generators with typical short residence times (seconds) can operate near ambient temperature where thermal decomposition is small. 

Environmental Impact of Ambient Ozone. Ozone can be toxic to plants, animals, and fish. The lethal dose, LD q, for albino mice is 3.8 ppmv for a 4-h exposure (156) the 96-h LC q for striped bass, channel catfish, and rainbow trout is 80, 30, and 9.3 ppb, respectively. Small, natural, and anthropogenic atmospheric ozone concentrations can increase the weathering and aging of materials such as plastics, paint, textiles, and mbber. For example, mbber is degraded by reaction of ozone with carbon—carbon double bonds of the mbber polymer, requiring the addition of aromatic amines as ozone scavengers (see Antioxidants Antiozonants). An ozone decomposing polymer (noXon) has been developed that destroys ozone in air or water (157). 

Tide 1 of the CAAA of 1990 focuses on utiHty units located in ozone nonattainment regions of the United States, which include approximately 100 different areas where national standards for ground-level ozone (O ) are exceeded. More than 900 utiHty boilers are located within the nonattainment zones, including 90 units impacted by Phase I of Tide 4. These boilers represent approximately 400,000 MW of installed capacity and 60% of the country s UtiHty boilers. 

Although it does not physically explain the nature of the removal process, deposition velocity has been used to account for removal due to impaction with vegetation near the surface or for chemical reactions with the surface. McMahon and Denison (12) gave many deposition velocities in their review paper. Examples (in cm s ) are sulfur dioxide, 0.5-1.2 ozone, 0.1-2.0 iodine, 0.7-2.8 and carbon dioxide, negligible. 

The emission inventory and the initial and boundary conditions of pollutant concentrations have a large impact on the ozone concentrations calculated by photochemical models. 

Gases or vapours that are water soluble or miscible or that are only soluble or highly reactive in other agents Absorption with multiple surface contact by atomizing liquid with spray nozzle or jet impaction Crabtree ozone analyser or midget venturi scrubber Water, acid, or alkali 5-25 60-100 Venturi scrubber satisfactory if dust is present Atomizer absorber will plug... 

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