FHWA Air Quality Performance Measures
Fiscal Year 2001

FHWA Human and Natural 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

EPA annually releases a report¹ documenting air pollution trends in the United States. EPA tracks trends associated with the criteria pollutants, and provides national emissions estimates by pollutant and source. We use 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 two-year time lag for the emission data. Therefore, data for fiscal years 2000 and 2001 are not available at this time, and the latest report contains only 1999 emissions.

In 1999, on-road transportation sources accounted for 51% of carbon monoxide (CO) emissions, 34% of nitrogen oxides (NOx) emissions, 29 % of volatile organic compounds (VOC) emissions, and 1% 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 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% reduction was establish for 1997 and 1998, and a target of 2% reductions were established for each year thereafter. In 1999, the data shows that in 1997 there was a 1.53% reduction in on-road mobile sources from 1996, in 1998 there was an additional 1.57% reduction, and in 1999 there was an additional 3.99% reduction equaling a 7.09% reduction of on-road mobile source emissions from the 1996 levels. These reductions exceed our target. Exhibits 1 and 2 summarize the on-road mobile source emissions data from 1989 to 1999.

* 1996 was selected as the baseline year to measure performance of the Strategic Plan.

Environmental Protection Agency (EPA) revised the emissions methodology used in calculating these estimates. The adjustments have led to changes in previously reported emissions estimates. Estimates used in this report reflect the current EPA methodology.

Source: EPA National Air Quality and Emissions Trends Report, 1999. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, NC. March 2001.

Exhibit 2
On-Road Mobile Source Emissions (1989-1999)

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

The FHWA Division Offices annually collect the information pertinent to the documentation of this air quality indicator. Performance is measured by a simple ratio; the number of nonattainment and maintenance 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). 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 year to see if there has been improvement.

The data for this indicator is collected 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. Due to the nature of the transportation conformity process, as well as the data collection process and reporting time frame, the results only represent a single point in time. Nonattainment and maintenance areas throughout the year may have experienced a change in their conformity status. However, this report only represents their status on July 1.

* Data is incomplete for 1999; only 40 States provided information.

As can be seen in Exhibit 3, a very high percentage of nonattainment and maintenance areas demonstrated that they were meeting their emission goals in fiscal year 2001. As of July 1, 2001, 97 out of 100 (97.0%) ozone areas, 43 out of 43 (100.0%) carbon monoxide (CO) areas, and 17 out of 18 (94.4%) particulate matter (PM-10) areas designated as nonattainment or maintenance had met their on-road mobile source emissions budgets. In 2000, 97.8% of ozone, 95.7% of CO, and 100% of PM-10 nonattainment and maintenance areas met their emissions budgets. As can be seen, a higher percentage of carbon monoxide areas met their emissions budgets in fiscal year 2001 compared with fiscal year 2000, while only a slightly lower percentage of ozone areas and a lower percentage PM-10 areas met their emissions budgets. It should be noted that the total number of nonattainment and maintenance areas with emissions budgets that were not meeting their emissions budgets on July 1 was the same in fiscal year 2000 and fiscal year 2001 (four areas).

Exhibit 4
Areas Meeting On-Road Mobile Source Emissions Goals
Fiscal Years 1996-2001

* Data is incomplete for 1999; only 40 States provided information.

¹EPA National Air Quality and Emissions Trends Report, 1999. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, NC. March 2001.

²1% of particulate matter (PM-10) emissions does not include fugitive dust.