Quantification of solvent emissions on ozone formation

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. 

Given the limitations of physical experiments to simulate atmospheric conditions, computer models have been developed to assess the impact of emissions on ozone. These models, called airshed models, are computerized representations of the atmospheric processes responsible for air pollution, and are core to air quality management. They have been applied in two fashions to assess how solvents affect ozone. One approach is to conduct a number of simulations with varying levels of solvent emissions. The second approach is to evaluate individual compounds and then calculate the incremental reactivity of solvent mix-t res. 9.2i  

While the types of simulations conducted by Derwent and Pearson are important to understanding the net effect of solvent emissions on ozone, there is an unanswered associated and important question, that being which specific solvents have the greatest impacts. 

This question is critical to assessing if one solvent leads to significantly more ozone formation than a viable substitute (or vice versa). 

To evaluate the contribution of individual organic compounds to ozone formation, the use of incremental reactivities (IR) was proposed, defined as the change in ozone caused by a change in the emissions of a VOC in an air pollution episode. To remove the dependence on the amount of VOC added, incremental reactivity is defined by equation [17.4.11] as the limit as the amount of VOC added approaches zero, i.e., as the derivative of ozone with respect to VOC  

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