Federal Highway Administration Air Quality Performance Measures
Fiscal Year (FY) 2003

FHWA Natural and Human Environment Goal: To protect and enhance the natural environment and communities affected by highway transportation.

In support of this goal, FHWA is committed to enhancing the community and social benefits of highway transportation, and improving the quality of the natural environment by reducing highway-related pollution and by protecting and enhancing ecosystems. Two air quality indicators currently measure our performance in meeting this strategic goal and objective:

• Reducing on-road mobile source emission by 20 percent in 10 years.
• Improving each year the percentage of nonattainment and maintenance areas that are meeting their mobile source emissions budgets.

1.   On-Road Mobile Source Emissions

Background

The EPA tracks trend associated with the criteria pollutants, and provides national emissions estimates by pollutant and source¹. FHWA uses this data to supply the performance indicators required to measure the reduction of on-road mobile source emissions. One limitation in using this report is that there is generally a 2-year time lag for the emission data. Further, FHWA and EPA were also in negotiations to revise the emissions model that was used to develop the 2001 data at the time this report was prepared. Therefore, data for fiscal years 2001, 2002 and 2003 are not available at this time, and the latest report contains only 2000 emissions.

Results for FY 2000

In 2000, on-road transportation sources accounted for 44 percent of carbon monoxide (CO) emissions, 33 percent of nitrogen oxides (NOx) emissions, 25 percent of volatile organic compounds (VOC) emissions, and 1 percent of particulate matter (PM-10) emissions². To establish the trend of on-road mobile source emissions, the annual emissions level is developed by taking the sum of estimated total estimated annual tonnage of on-road mobile source emissions of CO, NOx, VOC, and PM-10.

In order to develop the trend of on-road mobile source emissions, 1996 was selected as the baseline since it was the year with the most recently available data when the FHWA Strategic Plan was developed in 1998. The 1996 baseline is 69.1 million short tons of on-road mobile source emissions. To achieve the goal as set forth in the Strategic Plan, a target of a 1 percent reduction was established for 1997 and 1998, and a target of 2 percent reductions were established for each year thereafter. In 2000, the data shows that in 1997 there was a 1.53 percent reduction in on-road mobile sources from 1996, in 1998 there was an additional 1.57 percent reduction, in 1999 there was an additional 4.27 percent reduction, and in 2000 there was an additional 2.97 percent reduction. The sum total reduction of on-road mobile source emissions from the 1996 levels is 10.34 percent. These reductions exceed the target. Exhibits 1 and 2 illustrate the on-road mobile source emissions data from 1990 to 2000.

Exhibit 2: On-Road Mobile Source Emissions (1989-2000)

2.   Percent of Nonattainment and Maintenance Areas Meeting Mobile Source Emissions Budgets

Background

The second air quality indicator is a measure of the number of nonattainment and maintenance areas (including both urban and rural areas) which meet their on-road mobile source emissions budgets to the number of areas with adequate or approved on-road mobile source emissions budgets in their State Implementation Plans (SIPs). Designated areas without established on-road mobile source emissions budgets are not included in this report. An area may be designated for more than one criteria pollutant; in such areas, each budget is counted in the total. Designated areas that include multiple States are only counted once for purposes of this report. In calculating the percentages, the denominator is the number of nonattainment and maintenance areas that have emissions budgets. The numerator is the number of nonattainment and maintenance areas that are meeting their mobile source emissions budgets. In essence, the numerator is the number of areas with budgets that have demonstrated conformity. The ratio for the current year is then compared with previous years to determine if there has been improvement.

The FHWA division offices annually collect the data for this indicator at a snapshot in time each year, and by area and pollutant. July 1 has been chosen as the day of the snapshot each year. Nonattainment and maintenance areas throughout the year may have experienced a change in their conformity status. However, due to the nature of the transportation conformity process, as well as the data collection process and reporting period. This report only represents their status on July 1. Further, the EPA may designate or redesignate areas throughout the year. The total number of areas with emissions budgets therefore is not constant over the report years.

Results for FY 2003

As is illustrated in Exhibits 3 and 4, while a high percentage of nonattainment and maintenance areas demonstrated that they were meeting their emission goals in fiscal year 2003, it is down from 2002. As of July 1, 2003, 90 out of 93 (96.7 percent) ozone areas, 49 out of 53 (92.4) CO areas, and 29 out of 31 (93.5 percent) PM-10 areas designated as nonattainment or maintenance had met their on-road mobile source emissions budgets. In 2002, 98.0 percent of ozone, 100 percent of CO, and 96.3 percent of PM-10 nonattainment and maintenance areas met their emissions budgets. This year a lower percentage of areas met their on-road mobile source emissions budgets in all categories. An analysis of the areas not meeting their mobile source emissions budgets reveals that the largest contributor to the reduction in areas attaining their on-road mobile source emissions budgets were SIP-related problems (accounting for 4 lapses, representing 3 nonattainment areas) - specifically related to the required use of new vehicle emissions factor model. Another 2 of the lapses (representing 1 area - different pollutant) were for a failure to meet the plan update deadline. Another 3 lapses (representing the same area - 3 pollutants) is an area that has long been in lapse for reasons not related to transportation. It is important to note however that in each of these areas, FHWA worked closely with State and local officials and other Federal partners to reestablish conformity to minimize projects delays.

Exhibit 4: Areas Meeting On-Road Mobile Source Emission Goal (FY 1996-2001)
click image for text version
*Data is incomplete for 1999; only 40 States provided information.

Summary

The indicators demonstrate that the on-road mobile source emissions are on track for achieving a 20 percent reduction over the strategic 10-year period (1998-2007). The percentage of nonattainment and maintenance areas meeting their mobile source emissions budget have varied over time due to the "snapshot" nature of the measurement, however, the overall trend is generally favorable.

¹EPA National Emissions Inventory, Average Annual Emissions: All Criteria Pollutants, Years Included 1980, 1985, 1989-2000. Available: http://www.epa.gov/ttn/chief/trends/trends00/trends2000.pdf.

²1 percent of PM-10 emissions does not include fugitive dust.