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March 1998

UCAR-DU-Boulder project: E-mission accomplished


The atmospheric output of 670 vehicles was sampled on 26 and 27 January at the Mesa and Foothills Labs, respectively, as part of a collaboration with the University of Denver and the city of Boulder. DU's Gary Bishop brought the roadside emissions sampler created by colleague Don Stedman and used it to evaluate ML- and FL-bound vehicles during the commute hours of 7:00 to 10:00 a.m. Samples were taken two-thirds of the way up the mesa road and on Mitchell Lane near FL. (See the December-January issue of Staff Notes Monthly for more details on the sampling procedures.)

DU's Gary Bishop at work on the mesa road (below) and in his Winnebago/lab (left). (Photos by Carlye Calvin.)

Monday morning at the mesa, Bishop got usable readings on 280 vehicles. He then identified 17 vehicles with carbon monoxide emissions measuring 2.5% or more (of total weight, minus water vapor and extra air) to qualify for a "poor" rating and a $25 rebate coupon toward emissions-related repairs. Bishop found several vehicles in that group measuring 4% or higher. The average CO level for all vehicles climbing the hill on Monday morning (including visitors, school buses, and service vehicles) was 0.6%. True to prior research, the 6% of vehicles in the poor category were contributing about 50% of the CO pollution on the mesa road.

Tuesday at Foothills, Bishop gathered 390 usable readings and picked out 15 vehicles (3.8% of the total) in the "poor" category. The overall CO average for Foothills commuters was 0.58%.

All the NCAR shuttle vans were in the "good" category, as were the service vehicles visiting the two sites. Some vintage cars did better than some late models, but in general, emissions quality "scales with [vehicle] age, and age scales with salary," according to Bishop. The comparison to data collected at Interstate 25 in Denver (see table) shows many similarities to the Boulder data, says Bishop. "One would expect the UCAR/NCAR data sets to show slightly higher emissions because they contain some vehicles which were in a cold-start mode." Vehicles that haven't been driven at least a mile since being started will typically produce higher-than-normal CO emissions.

The weather cooperated with the project, providing cool morning temperatures around the freezing mark. While Monday had some gusts, winds were relatively mild on both days. (High winds, snow, or severe cold render the on-the-fly testing invalid.)

Staffing the information table at ML over the lunch hour were Bishop, Ron Ruth (ATD), Pat Harris (FSS), Julie Herman from the city of Boulder's Office of Environmental Affairs, and Hetty Versteege from the Boulder Energy Conservation Center. On Tuesday at FL, Bishop and Ron were joined by Leonard Sitongia (HAO) and Kimberly Bruckner of BECC.

At the information tables, Bishop used a detector with its top removed to explain how the measurements are taken. Staff asked questions and tried to remember their license plate numbers to see if they were on the "baddies" list. There were plenty of cheers and sighs of relief from those not on the list. Several people whose vehicles made the list were surprised, since they had passed the state's emissions test recently. This gave Bishop the opportunity to explain the higher standards he used and the benefits of frequent testing for vehicles hovering around the "poor" level. •ZG and BH

As of late February, a few vouchers had yet to be claimed. Check with your site receptionist (ML or FL) or go to UCAR/DU/Boulder Emissions Project to see if your vehicle qualifies.

The results

Location Mesa Foothills Denver, 6th/I-25 (1/97)

Number of vehicles 289 393 46,120
Mean % CO 0.69 0.59 0.51
Median % CO 0.2 0.15 0.1
Percent of fleet with less than 1% CO 83% 88% 87%
Percent of CO emissions contributed by the dirtiest 10% of fleet 62% 67% 67%
Average % CO emissions of dirtiest 10% of fleet 4.4% 4.1% 3.4%


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Edited by Bob Henson, bhenson@ucar.edu

Prepared for the Web by Jacque Marshall