This section includes relevant Policy Documents which might be helpful for the user’s own assessment of the applicability of cleaner bus, truck, and fuels options. These assessments should be placed in the broader policy context, take into account other available air quality options and specific local economic and environmental conditions. The crucial question of these assessments is how to phase in the adoption of cleaner technology cost-effectively, and what non-technical policies are essential to maximize chances of successful implementation of technology-based policies.