Multi-pollutant benefits of on-road motor vehicle control strategies

Focus Area

Air Quality


Air Quality






1-2 years

Research Idea Scope

While there are a number of published studies that provide information to state and local agencies about the potential emission reduction benefits of control strategies that are designed to reduce either criteria air pollutant, greenhouse gas, or air toxic compound emissions, stakeholders still identify this area as one where practitioners do not have consistent methods and tools for analysis. In 2001, FHWA published a guide to 19 air quality analysis tools, but that guide is now largely out-of-date since tools have evolved and many are no longer supported. The 2006 FHWA report, Multi-Pollutant Emission Benefits of Transportation Strategies, provides examples of calculation procedures that can be used for a full range of air quality strategies, but practitioners would need to operationalize these procedures in a tool, and emission factors are outdated. The NCHRP 25-25, Task 59 report entitled “Evaluate the Interactions between Transportation-Related Particulate Matter, Ozone, Air Toxics, Climate Change, and Other Air-Pollutant Control Strategies” (2010) provides practitioners with information about the estimated multi-pollutant emission reductions and cost effectiveness of transportation-related control measures based on analyses performed in different cities and available in the literature. This Task 59 report is organized by (1) TDM strategies, (2) transportation system management strategies, and (3) vehicle and fuel technology strategies. However, this report only provides information on strategy benefits, rather than calculation procedures. In addition, some state and regional agencies have developed their own spreadsheet tools-often for the purpose of quantifying Congestion Mitigation and Air Quality Improvement Program (CMAQ) project benefits. For this new research project, it is recommended that the focus be on providing a set of analysis practices that practitioners can follow to use the analysis tools available at the state and urban area level to provide quantitative estimates of the emission changes for all of the pollutants in EPA’s MOVES model, plus non-CO2 greenhouse gases like nitrous oxide and methane, as well as the mobile source air toxics. The MSAT analysis should address how practitioners should use MOVES to estimate air toxics emissions for the years and vehicle types of interest. (Note that when the Task 59 report was prepared, the EPA MOVES model had not been released, so this study would be expected to address how the MOVES model can be used (or adapted) to provide consistent emissions assessments. It would also be expected to allow practitioners to incorporate MOVES updates into the provided calculation frameworks. ) This project is expected to provide descriptions of recent quantitative emission benefit quantification tools such as those sponsored recently by EPA’s Office of Transportation and Air Quality and FHWA. In instances where these tools focus just on either criteria pollutants or GHGs, this project would be expected to provide recommendations about how those tools could be extended to estimate emission reductions for the spectrum of pollutants/gases of interest to this project. While this research effort is not expected to produce new comprehensive models for control measure analysis, it is expected that the selected contractor will develop targeted spreadsheet level quantification tools that practitioners can use to produce quantitative assessments of selected options within a category, where existing tools are not currently available. This project is also expected to address new innovative mitigation measures that have been explored by regulatory agencies in recent years. This subject area is expected to be a priority for state and local transportation agencies and air pollution control agencies as they develop new control plans when EPA revises the ozone NAAQS to a level that is expected to be in the range of 60 to 70 ppb (from the current 75 ppb NAAQS) and states and cities develop or refine climate action plans to meet future year targets for transportation sector greenhouse gas emission reductions. In addition, there are a number of PM-2.5 nonattainment areas that are considering transportation sector control options in their attainment planning.

Urgency and Payoff

Given the economic challenges of the past several years, federal and state support for environmental control programs (as well as other programs) is under severe pressure. Therefore, funds for improving air quality must be used very judiciously; multi-pollutant control strategies offer the opportunity to more systematically and efficiently address air quality challenges. Key benefits of multi-pollutant strategies include: 1) They help eliminate the need to study the impacts of each pollutant separately since none of the pollutants exist in the atmosphere separately; and 2) They help the regulatory community design more cost effective control strategies that advance multiple goals. In addition, multi-pollutant approaches assist agencies in meeting “streamlining” goals to ease implementation of environmental requirements. The need to streamline environmental reviews has been of increasing interest recently as a method to help support the economic recovery. This research needs to be completed and available to states and MPOs before the states have to begin developing state implementation plans in response to the expected lowering of the ozone standard to a level between 60 and 70 parts per billion.

Suggested By

Joe Zietsman on behalf of TRB ADC 20 Research subcommittee TRB Air Quality ADC 20 Committee

[email protected]