Maximum incremental reactivity factor

Table 4. Maximum incremental reactivity factor for some selected exhaust gas components.

Maximum incremental reactivity factor (g ozone per g component)... 

The order of the compounds determined by the magnitude of the mass emissions is not intended to reflect the relative influence of these compounds on atmospheric chemistry, greenhouse effect, or other atmospheric phenomena. To illustrate this point, compare in table I-C-5 the orders of importance of the top 31 species in mass emissions in table I-C-2 as estimated from a consideration of criteria other than mass emissions. We list the normalized relative values for molecular emissions (proportional to mass emissions/molecular weight), relative rate of attack by OH radicals (proportional to molecular emissions x oh), the relative rate of ozone generation as estimated for a polluted urban atmosphere (proportional to mass emissions x MIR, the maximum incremental reactivity factor Carter, 1998), and the relative number of CO2 molecules that atmospheric oxidation of this species will ultimately generate (proportional to molecular emissions x number of C-atoms molecule" ). The latter comparison... 

McNair, L. A., A. G. Russell, M. T. Odnian, B. E. Croes, and L. Kao, Airshed Model Evaluation of Reactivity Adjustment Factors Calculated with the Maximum Incremental Reactivity Scale for Transitional-Low Emission Vehicles, J. Air Waste Manage. Assoc., 44, 900-907 (1994). 

As a fourth step, discussion continues for the introduction of emission limits for other exhaust gas components, and for particulate matter of diesel powered vehicles. For example, there has been discussion in the USA and some European countries on separate - additional - emission limits for carbon dioxide, benzene and/or aldehydes. In the USA there is a project to consider an additional ozone-formation factor to be allocated to the tailpipe emission of passenger cars. This is because each exhaust gas component has a different potential to contribute to atmospheric ozone formation. This potential is quantified according to the theory of Carter by the maximum incremental reactivity (MIR) factor, expressed as grams of... 

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