(b) A district may use an alternative emission reduction strategy which achieves less than an average of 5 percent per year reduction in districtwide emissions if the district demonstrates to the state board, and the state board concurs in, either of the following:

1. (1) That the alternative emission reduction strategy is equal to or more effective than districtwide emission reductions in improving air quality.
2. (2) That despite the inclusion of every feasible measure in the plan, and an expeditious adoption schedule, the district is unable to achieve at least a 5-percent annual reduction in districtwide emissions.