Recent Developments in California and the U.S. Bart Croes Air Resources Board Sacramento, California 6 March, 1996

Outline F Ambient Air Techniques F Fuel-Based Inventories F Tunnel/Roadway Studies F Aloft Measurement Studies F Remote Sensing Studies F Recommendations

Ambient Air Techniques F Ratios F Source Reconciliation –semi-volatile PAHs F GRACE/SAFER –Derives source profiles –Requires large VOC dataset

GRACE/SAFER F Graphical Ratio Analysis for Composition Estimates –Define limits of species ratios F Source Apportionment by Factors with Explicit Restrictions –Multivariate receptor model –GRACE and nonnegative source compositions F Henry et al. (1994) –1990 Atlanta Ozone Precursor Study –62% tailpipe exhaust –15% whole gasoline evaporation – 4% headspace vapor

Fuel-Based Inventories F Requirements –Fuel sales, relative fuel economies –CO/CO 2 and HC/CO 2 measurements –VOC/CO and NOx/CO correlations F Limitations –Stabilized exhaust only –Regional inventory only F Singer and Harley (1996) –CO agrees with MVEI 7G –58% of CO from cars and trucks > 10 years

Tunnel/Roadway Studies F Caldecott Tunnel (San Francisco) –Effects of oxygenated gasoline –Effects of reformulated gasoline F PM10/PM2.5 Studies –University of California at Davis –University of California at Riverside –Highways not a PM source

Aloft Measurement Studies F Tower/Tethered Balloon –Walnut Grove television tower single ozone analyzersingle ozone analyzer Teflon lines at 5 levels to 500 mTeflon lines at 5 levels to 500 m F Manned Balloon –U.S. Air Force 250 kg payload250 kg payload ozone, NOx, VOC samplingozone, NOx, VOC sampling F Aircraft –SCOS97-NARSTO 4 aircraft4 aircraft ozone, NOx, NOy, CO, VOC samplingozone, NOx, NOy, CO, VOC sampling

Remote Sensing Studies F Roadway –Remote Sensing Device –CO, “HC”, NOx F Area Source –University of California at Davis F Volume Source –Duke Forest, North Carolina –Texas petroleum refinery

Recommendations F Release tracer gas(es) F Measure CO and CO 2 F Evaluate source profiles with GRACE/SAFER F Timing of emissions is a critical factor in ozone formation