Table XVII: Major Analysis Assumptions

Federal Motor Vehicle Control Program Assumed to be on
schedule and to be Effective at this Altitude (AP-42)

Automotive Inspection/Maintenance not Assumed

City of Boulder not Included in Analysis Concentrations
Calculated

Ozone from Set of Reactions Derived for Los Angeles, Calif-
ornia

Highway and DRCOG Traffic and Population Inputs are Appro-
priate

No Small Scale Localized Analysis will be Performed

Phase II Vapor Recovery Strategy not Assumed

Emission Inventory The development of the emissions data for
the various pollutants for the appropriate averaging times con-
stituted the majority of time spent on this effort. The primary
sources of pollutants were considered for both the stationary
and transportation classifications. Tables XVIII and XIX outline
the emission source contributions for each pollutant. Table XVIII
illustrates the daily contributions for the two pollutants which
have short term standards and Table XIX addresses the annual con-
tributions for the two pollutants which have long term standards.

The source contributions for carbon monoxide in Table XVIII illustrate that automotive usage is the major factor associated with CO emissions. Hydrocarbon emission contributions show numerous source categories and yet the major contributors to hydrocarbon emissions in Denver are transportation sources.

The source contributions for particulates in Table XIX are interesting. Almost one half of the particulate contribution is attributed to dust and sand emissions from automotive travel on paved roads. The total contribution derived from automotive useage is greater than 55%. Construction activities and point sources account for much of the remainder.

Nitrogen dioxide contributions (Table XIX) are split evenly between automotive and point source emissions.

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Results

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The attainment status for ambient air quality standards in Denver by 1985 is summarized in Table XX. The non-attainment status refers to that situation where ambient air quality standards are currently being exceeded and will continue to be exceeded in 1985. The maintenance status refers to that situation where ambient air quality standards are not currently being exceeded, but will be exceeded in the year 1985. Standards for four pollutants of concern will be violated in 1985 in Denver.

The spatial area of violations was determined for each pollutant for each study year as shown in Table XXI. Decreasing areas of violation are evident for carbon monoxide and ozone, while it is projected that violation of standards for particulates and nitrogen dioxide will extend over a greater area. Except for a decrease is ozone, the 1980 air quality situation has more square miles of violations of the ambient air quality standards than for 1975. The significant downward trend noted for carbon monoxide from 1980 to 1985 is directly attributable to the FMVC program (automotive emission standards).

The

Isopleth maps depicting contours of projected air pollution concentrations for the year 1985 are shown in Figures 13 through 16. Figure 13 depicts the worst-case 8-hour carbon monoxide picture. highest concentrations occur in the core city area with hot spots noted on certain major highways.

The worst case one-hour ozone concentrations, shown in Figure 14, portray a different case. The maximum values for ozone occur in the suburban areas rather than in the core city. Although the maximum values appear in the western suburban area in Figure 15, it is felt that the maximum can occur in other perimeter suburban areas as well.

The particulate contour map in Figure 16 illustrates the annual concentrations projected for the year 1985. The entire area is in violation of the State standard with the maximum values occurring in the core city bisected north to south by the Platte River and the I-25 Freeway. The maximum area extends north beyond the Denver city limits into Adams County.

Figure 16 illustrates the annual nitrogen dioxide concentration. The results are similar in scale to those of particulates with maximum values occurring in the core city area with extrusions into Adams County. The hot spot situated to the east of the principal maximum is a consequence of Stapleton Airport nitrogen dioxide emissions.

Summary

Both the 1-hour standard of 35 parts per million (ppm) and the 8-hour standard of 9 ppm for carbon monoxide will be violated in the Denver metropolitan area in 1980 and 1985. Actual carbon monoxide levels are expected to remain about the same until 1980, then decrease by nearly half from 1980 to 1985, largely because of the proposed Federal motor vehicle emissions control program which will require 1977 and later model year automobiles to meet Federal emissions standards at the point of sale.

Levels of ozone will continue to violate the standard of .08 ppm in 1980 and 1985, but measured levels of the pollutant are projected to decline, primarily after 1980.

Particulate levels in 1980 and 1985 will violate both the annual standard for particulates of 45 micrograms per cubic meter and the 24-hour standard of 150 micrograms per cubic meter. The particulate standard is violated now, but actual amounts of particulate matter in the air will be greater in future years.