Background Information

Carbon monoxide (CO) is a poisonous gas that damages the central nervous system and, in high enough concentrations, causes death. It is a colorless, odorless, tasteless gas that enters the body through the lungs, where it is absorbed by the bloodstream and combines with the hemoglobin that supplies oxygen to all organs of the body. Since CO combines with hemoglobin more readily than oxygen does, the body is deprived of its oxygen supply. The result is a weakened heart and a reduced blood supply to the rest of the body. The severity of carbon monoxide-induced health effects depends on the concentration being inhaled and the length of time a person is exposed.

Carbon monoxide occurs naturally in the air from such processes as forest fires and decomposing methane gas. Natural concentrations range from 0.05 to 0.15 parts per million (ppm). This range is very small compared to concentrations found in most cities, which contain about 100 times as much CO. In urban areas, CO is produced primarily by motor vehicles, whose emissions increase carbon monoxide concentrations during morning and evening rush hours.

The Environmental Protection Agency has developed a standard for CO concentrations. Averaged over an eight-hour period, concentrations may not exceed 9 ppm more than once per year in a given location. Denver and Boulder, Colorado, as well as other U.S. cities have reduced their CO concentration levels by reducing emissions from automobiles, wood burning stoves, and fireplaces, and industry.

In this activity's procedure, you will complete three time series plots. A time series is a plot of time against some other variable. You will use data collected on January 1, 1989, in the cities of Denver and Boulder, Colorado. When plotting Denver data points, use the labeled graphs shown under the title, "Denver Carbon Monoxide Time Series" (Figure 8.1). When plotting Boulder data points, use the labeled graphs shown under the title, "Boulder Carbon Monoxide Time Series" (Figure 8.2).

In both the Denver and Boulder time series plots, Plot 1 (top) shows time versus CO concentration. Plot 2 (middle) shows time versus wind speed in knots. Plot 3 (bottom) shows time versus wind direction in degrees. In Plot 3, wind direction is indicated by the azimuth direction in degrees, as well as in cardinal directions for north, south, east, and west. Azimuth is the direction measured clockwise from the north through 360o. To better understand the meaning of azimuth direction, examine the diagrams of "Azimuth and Cardinal Directions" next to Plot 3 (bottom) on both Figure 8.1 and 8.2.

The data for plotting in Figures 8.1 and 8.2 is available in Table 8.1, and was provided by the Colorado Air Pollution Control Division Daily Pollutant Standard Index Report.

Table 8.1. Observed CO Level, Wind Speed, and Wind Direction for the Cities of Denver and Boulder, Colorado - January 1, 1989.
(CO in ppm - Wind Speed in Knots - Wind Direction (From) in Degrees)
Print at 92% for use in this Activity.

Notes





Procedure

  1. On Plot 1 of the Denver Carbon Monoxide Time Series (Figure 8.1), draw a horizontal line at 9 ppm that extends from hour zero to hour 24. Label this line "Recommended Maximum CO Level."

    Figure 8.1. Denver Carbon Monoxide Time Series
    Print at 92% for use in this Activity.

  2. Repeat the procedure in Step 1 for Plot 1 of the Boulder Carbon Monoxide Time Series (Figure 8.2).

    Figure 8.2. Boulder Carbon Monoxide Time Series
    Print at 92% for use in this Activity.

  3. Using data provided in Table 8.1, plot the curves on the grids provided in Figure 8.1 for the CO level in ppm (Plot 1), wind speed in knots (Plot 2), and wind direction (Plot 3) for Denver.

  4. Repeat the procedure in Step 3 for Boulder (Figure 8.2).




Questions

  1. For how many hours did the CO level equal or exceed the recommended maximum level...

    In Denver? ______________
    In Boulder? ______________


  2. What are the maximum and minimum wind speeds for Denver?

    Maximum = ___________________
    Minimum = ___________________


  3. What are the maximum and minimum wind speeds for Boulder?

    Maximum = ___________________
    Minimum = ___________________


  4. What is the range (subtract the minimum from the maximum) for the wind speed...

    In Denver? ______________
    In Boulder? ______________


  5. From what direction did the wind blow most often...

    In Denver? ______________
    In Boulder? ______________


  6. What relationship is there between CO level and wind speed...

    For Denver? ______________
    For Boulder? ______________


  7. At what time of the day was the CO maximum...

    For Denver? ______________

    Why is this unusual? (Hint: New Year's Day)

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

  8. Using a dashed line (-----------), draw a curve on the Denver graph (Figure 8.1) that would illustrate the CO level on a typical work day.

  9. As shown in the diagram to the right, the city of Denver is located in the South Platte River Valley. Near Denver, the South Platte River flows roughly from south-southwest to north- northeast. Boulder Creek, approximately 30 miles north of Denver, flows out of the mountains and through Boulder roughly from west to east. To the west of both cities are the foothills of the Rocky Mountains. How does the topography affect the wind direction in both locations? Question 9 Diagram


    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________

    _____________________________________________________________________________


Figure 8.3. Questions Sheet
Print at 92% for use in this Activity.




Conclusions

Review the problem stated in the workstation screen graphic
at the top of this web page and write your conclusions here.



Figure 8.4. Conclusions Sheet
Print at 92% for use in this Activity.