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Basics of Reactivity. March 1, 2001 Dongmin Luo Research Division California Air Resources Board. Ozone Problem. Ozone is an ambient ground level pollutant of health concern Significant reductions have been achieved in ambient ozone levels
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Basics of Reactivity March 1, 2001 Dongmin Luo Research Division California Air Resources Board
Ozone Problem • Ozone is an ambient ground level pollutant of health concern • Significant reductions have been achieved in ambient ozone levels • However, many urban areas in CA still exceed ozone air quality standards • Additional control strategies are needed
Ozone Formation • Ozone is formed from reactions of VOCs and NOx in sunlight • Very low levels of ozone are formed if VOCs are absent • No ozone is formed if NOx is absent • Many types of VOCs promote ozone formation
Ozone Control • NOx control • VOC control • Mass-based • Reactivity-based
VOC Reactivity • Thousands of VOCs present in the atmosphere • VOCs differ in their effects on ozone formation e.g., 1 g ethane = 0.31 g ozone 1 g ethylene = 9.1 g ozone alkenes > aromatics > alkanes • Reactivity-based control strategy recognizes the differing reactivities
Measures of Reactivity • Ozone formation rate • NO2 formation rate • VOC loss rate • KOH rate constant
Ozone Reactivity • Incremental Reactivity • Maximum Incremental Reactivity (MIR) • Maximum Ozone Incremental Reactivity (MOIR) • Equal Benefit Incremental Reactivity (EBIR) • Relative Reactivity
Incremental Reactivity • MIR is the most appropriate for regulatory purpose • MIR in California regulation • LEV/CF regulation • Aerosol coatings regulation