SEPA TECHNICAL PLAN TO ADDRESS VEHICLE POLLUTION
Generally ，the goal of a motor vehicle pollution control program is to reduceemissions from motor vehicles in-use to the degree necessary to achieve healthyair quality as rapidly as possible or ，failing that for reasons of impracticality，to the practical limits of effective technological，economic，and social feasibility.Achievement of this goal generally requires a comprehensive strategy encompassingemissions standards for new vehicles，clean fuels，and programs designed to assurethat vehicles are maintained in a manner that minimizes their emissions.Finally，to complete this comprehensive strategy ，an effective program for traffic anddemand management that limits the demand for and use of all vehicles must be formulated.Ideally ，to be politically feasible ，these emission reduction goals should beachieved in the least costly manner.Figure 1illustrates the elements of a comprehensivevehicle pollution control strategy.
Standards for permissible levels of exhaust and evaporative emissions from motorvehicles should be based on a realistic assessment of costs and benefits keepingin view the technical and administrative feasibility of proposed countermeasures.Technological approaches to achieve the desired emission standards may include fittingnew vehicles with emission control devices，such as catalytic converters or particulatetraps ，requiring such devices to be retrofitted to existing vehicles，and modifying
