Prices vs Quantities with Multiple Pollutants

We examine the choice of policy instrument price, quantity, or a mix of the two when two pollutants are regulated and firms’ abatement costs are private information. A key parameter that affects this choice is the technological externality between the abatement efforts involved, i.e., whether they are substitutes or complements. If they are complements, a mix policy instrument with a tax on one pollutant and a quota on the other is sometime preferable, even if the pollutants are identical in terms of benefits and costs of abatement. Yet, if they are substitutes, the mix policy is dominated by taxes or quotas.<p>