It is hoped that by understanding the full array of options to reduce emissions, elected officials will appreciate the importance of transportation conformity as a tool that serves the twin goals of clean air and improved mobility. The key transportation-related pollutants are ozone, carbon monoxide, and particulates. A region can be designated as a nonattainment or maintenance area for one or more pollutants and can have different classifications based upon the severity of violations for each pollutant. Transportation officials are responsible for finding ways to reduce emissions from on-road mobile sources. Stationary sources are relatively large, fixed sources of pollution, such as manufacturing facilities or power plants.
Area sources consist of other fixed, but smaller facilities, such as gas stations or dry cleaners.
Mobile sources include on-road sources of pollution, such as cars and trucks, and are linked to the highway and transportation infrastructure. For each source category, the SIP assigns emission reduction targets. Challenges for Transportation Officials Transportation decision makers face two distinct challenges. First, they must work with State air quality officials to assess trade-offs between mobile and stationary source emission reduction programs and adopt a specific set of SIP strategies which enable them to demonstrate that the reductions needed to reach attainment can be achieved. Strategies vary in cost, effectiveness, and ease of implementation, and a host of factors need to be considered in deciding which strategies to select.