Air Quality Forecasting For the Spare the Air Program in Sacramento, California: Summary of Four Years of Ozone Forecasting. (Formerly Paper 16.6)

In 1997, the U.S. Environmental Protection Agency (EPA) revised the National Ambient Air Quality Standard (NAAQS) for ozone to reflect more recent health-effects studies that suggest that respiratory damage can occur at lower concentrations. Under the more-stringent revised standard, more regions will exceed the NAAQS for ozone. Thus, more local and state air quality agencies will need to forecast ozone to alert the public of unhealthy air.

This paper describes the ozone-forecasting program developed for the Sacramento metropolitan region in California and evaluates its operational performance. In particular, we discuss the techniques used to forecast ozone, including the use of regression, decision trees, rules of the thumb, and phenomenological forecasting techniques. Also presented are performance metrics to evaluate forecast accuracy, precision, and false alarm rates. Lessons learned from this four-year ozone-forecasting program and recommendations for other programs are discussed.