A MONTE-CARLO SIMULATION OF THE OZONE ATTAINMENT PROCESS

A Monte-Carlo simulation of the approach to attainment of the National Ambient Air Quality Standard for ozone has been performed for the Cal ifornia Bay Area Air Quality Management District. Four compliance test s together with different design values are used in the simulation. Th e results show that the present compliance test requiring a zero-perce nt chance of violation and the design value represented by the fourth highest value in three years makes both the standard and the control r equirement much more stringent than generally assumed. In fact, to att ain the standard on a long-term basis would require annual means and a nnual second-highest values that are close to those of the rural backg round ozone. The simulation also shows that by taking into account the fluctuation of ozone concentrations in the compliance test, such as a t test, and by using a design value consistent with the test, a stand ard defined in terms of the three-year mean of the annual second-highe st values not only is more consistent with the currently-perceived str ingency of the present standard, but may also be attainable with a mor e reasonable control requirement.