A sample study of Denver-area drivers indicates almost all are aware of air-quality advisories and voluntary driving restrictions during high-pollution days in the fall and winter, but the advisories have no significant effect on commuters聮 transportation habits.
University of Colorado at Boulder geography department Assistant Professor Peter Blanken and undergraduates Jennifer Dillon and Genevieve Wismann mailed a 14-question, anonymous survey to 1,000 randomly selected vehicle owners regarding their driving habits and how they responded to high-pollution advisories. Five hundred surveys were mailed to Westminster residents and 500 were sent to Boulder residents.
The CU-Boulder research team had hypothesized the air quality advisories had no effect on voluntary driving restrictions due to lack of awareness and understanding, a lack of alternative means of travel or lack of concern. But 94 percent of the 281 people that completed and returned the surveys said they were aware of what the high-pollution advisories meant and 93 percent heard the posting via the media at least once a day prior to work.
"We were somewhat surprised to find that people were fully aware of the air pollution advisories, were hearing them through the media at appropriate times and understanding them," said Blanken, also a faculty member in CU-Boulder聮s Environmental Studies Program. "But the results also indicate that cars are very dear to our culture. Clearly the message is getting out, but it is not affecting behavior."
Of the respondents, 79 percent said they regularly commuted to work and 5 percent said they sometimes commuted. Seventy-five percent of commuters lived within 10 miles of their work, and three-quarters of those people commuted alone in their cars. Although 32 percent of commuters in the study lived within 2.5 miles of their jobs, only 11 percent walked or bicycled to work, according to the survey.
Because of the Denver area聮s high vehicle use, high altitude, relatively clear skies and frequent winter temperature inversions, the Colorado Department of Public Health issues daily air quality advisories during the high-pollution season from Nov. 1 to March 31. The advisories are issued in an attempt to cut down air pollution by using voluntary driving restrictions and a mandatory wood-burning ban.
The advisories are issued at 4 p.m. each day, disseminated predominately by television, radio and newspapers and are valid for 24 hours. Red advisory days indicate poor or worsening air quality, a mandatory ban on wood burning and voluntary driving restrictions. Blue advisories indicate good air quality and no wood burning or driving restrictions. During the 1999-2000 high-pollution season, there were 48 red and 102 blue advisory days.
Of single-occupant commuters, 76 percent said they never changed their means of transportation based on pollution advisories, according to the study. And 12 percent of single-occupant commuters said they changed their mode of transportation under red advisories only if it was convenient. Many responders reported they had no alternate means of transportation or that methods such as public transit were too inconvenient.
The CU-Boulder study was recently accepted for publication in the journal Atmospheric Environment. Published in Manchester, England, Atmospheric Environment is an international atmospheric science journal published 30 times per year.
The two co-authors of the study, Dillon and Wismann, were able to participate in the study through CU-Boulder聮s Undergraduate Research Opportunities Program, or UROP. UROP students work directly with faculty or researchers on particular research projects, receiving stipends averaging about $750 per semester each. Since 1986, about 4,000 undergraduates have received more than $3 million from CU-Boulder through UROP.
Of the 53 percent of survey respondents who said they burned wood, 86 percent reported they abided by the mandatory wood-burning ban on red advisory days. The authors hypothesized the high compliance was due to the ban being mandatory, easy to enforce and because noncompliance was accompanied by a monetary fine.
Less than 1 percent of the respondents felt the advisories were effective in reducing automobile pollution. The total distance traveled by Denver area motorists was roughly 48 million miles daily in 1996, 55 million miles daily in 1999 and is projected to reach 70 million miles daily by 2020, said Blanken.
One respondent commented that voluntary driving restrictions "have no teeth," a view shared by Blanken. The CU researchers suggested possible alternatives to mitigate the problem such as subsidizing public transit passes, improving public transit schedules and routes, improving bicycle and walking paths and providing tax rebates for fuel-efficient cars.