Additional Resources Save and Share How to Build a Retrofit Project Step 1: Determine Target Emissions Step 2: Identify Candidate Equipment and Technology Options Step 3: Assess Cost Effectiveness Step 4: Emission Credits Step 5: Consider Implementation Issues

 

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Step 1: Determine Target Emissions

A first step to developing a program is to determine which pollutants are targeted for emission reductions. In most cases, retrofit strategies will target primarily nitrogen oxides (NO_x) and/or particulate matter (PM) emissions, although some retrofits also reduce volatile organic compounds (VOCs) and carbon monoxide (CO). NO_x emissions, along with VOCs, are a key precursor to ground-level ozone and many nonattainment areas are required to substantially reduce NO_x emissions in order to attain the National Ambient Air Quality Standards (NAAQS). Reducing PM emissions is also a high priority in many regions.

For on-road emissions, each State Implementation Plan (SIP) includes a motor vehicle emissions budget that explicitly sets a limit for on-road emissions of each specific pollutant (i.e., NO_x, CO, PM). This budget applies to certain future years (analysis years) and transportation agencies must demonstrate that they can meet these emissions limits in each year required in the SIP and for each pollutant that exceeds the NAAQS. By reviewing these budgets, one can determine which pollutants need to be reduced, when the reductions are needed, and how much of a reduction is needed in order to attain the NAAQS. Many MPOs need to demonstrate NOx and PM reduction in the next 0-5 years, so diesel retrofits may be an ideal solution in these areas.

For off-road emissions (e.g., construction equipment, marine vessels, locomotives, etc.), the SIP will show the level of emissions reductions needed for each major pollutant type and must identify specifically how and when those emission reductions will be achieved. The SIP must include enforceable commitments to making these reductions. So, by reviewing the SIP and the motor vehicle emissions budgets, you can determine which emissions sources need to be addressed, which pollutants need to be reduced, when reductions are needed, and the state's (or nonattainment area's) proposed strategies.