Abstract
Many air quality management districts throughout the country conduct public education programs during the summer ozone season to encourage members of the public to reduce their driving on days forecast to violate ozone air quality standards. The research study developed a relatively simple and low-cost method for quantifying the travel and emission impacts of these programs, often called "Spare the Air" in California. The study developed survey methods that included both a long, detailed questionnaire and a short, simple one. Through these questionnaires, the study collected comprehensive travel data of a random sample of the general population and of individuals who said they responded to the Spare the Air (STA) message. The data, collected during two summer ozone seasons in Sacramento, allowed researchers to compare the travel behavior of the same individuals on both STA and regular (non-STA) summer days and of STA participants and nonparticipants. The study found a statistically significant difference between self-reported vehicle trip reductions and measured vehicle trip changes due to STA programs among STA participants. A correction factor was derived based on this research finding. By applying the correction factor to a simple and less costly survey, similar to the simple questionnaire used in this study, air districts will be able to adjust future self-reported vehicle trip reductions and extrapolate them to the entire regional population of drivers within an acceptable margin of error.
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