This figure illustrates the policy trade-offs for a region where the MB curve (thick solid line) is relatively low. The horizontal axis indicates the abatement path toward cleaner air (left). The curves show the ideal, least-cost abatement path (thin solid line ideal MAC frontier) and two potential inefficient, high-cost paths (dotted lines). The labeled areas represent the static gaps between marginal benefits and costs at different pollution levels. Area C represents the state with net social benefits. Areas A and B schematically illustrate the state where, if a society adopts an inefficient, high-cost path, its high marginal costs (dotted lines) far exceed the marginal benefits (thick solid line). This highlights the critical need for low-MB regions to prioritize low-cost interventions, as inefficient policies risk marginal costs substantially exceeding marginal benefits.