摘要：Reducing nitrogen oxide (NOx) emissions in the eastern United States has become the focus ofefforts to meet ozone air quality goals and will be useful for reducing particulate matter (PM)concentrations in the future. This paper addresses many aspects of the debate over the appropriateapproach for obtaining reductions in NOxemissions from point sources beyond those called for in theClean Air Act Amendments of 1990. Data on NOxcontrol technologies and their associated costs,spatial models linking NOxemissions and air quality, and benefit estimates of the health effects ofchanges in ozone and PM concentrations are combined to allow an analysis of alternative policies inthirteen states in the eastern United States. The first part of the study examines the cost and otherconsequences of a command-and-control approach embodied in the Environmental ProtectionAgency's (EPA) NOxSIP call, which envisions large reductions in NOxfrom electric utilities andother point sources. These results are compared to the alternative policy of ton-for-ton NOxemissions trading, similar to that proposed by the EPA for utilities. We find that emission reductiontargets can be met at roughly 50% cost savings under a trading program when there are notransaction costs.The paper examines a number of alternative economic incentive policies that have the potential toimprove upon the utility NOxtrading plan proposed by EPA, including incorporation of other pointsources in the trading program, incorporation of ancillary PM benefits to ozone reductions in thetrading program, and trading on the basis of ozone exposures that incorporates the spatial impact ofemissions on ozone levels. For the latter analysis, we examine spatially differentiated permit systemsfor reducing ozone exposures under different and uncertain meteorological conditions, including anempirical analysis of the trade-off between the reliability (or degree of certainty) of meeting ozoneexposure reduction targets and the cost of NOxcontrol. Finally, several policies that combine costsand health benefits from both ozone and PM reductions are compared to command-and-control andsingle-pollutant trading policies. The first of these is a full multipollutant trading system thatachieves a health benefit goal, with the interpollutant trading ratios governed by the ratio of unithealth benefits of ozone and PM. Then, a model that maximizes aggregate benefits from both ozoneand PM exposure reductions net of the costs of NOxcontrols is estimated.EPA's program appears to be reasonably cost-effective compared to all of the other more complextrading programs we examined. It may even be considered an optimal policy that maximizes netaggregate benefits if the high estimate of benefits is used in which mortality risk is linked to ozoneexposure. Without this controversial assumption, however, we find that EPA's NOxreduction targetis far too large.
