Recent Developments in Recent Developments in California and the U.S.California and the U.S.

Bart Croes

Air Resources Board

Sacramento, California

6 March, 19966 March, 1996

OutlineOutline

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

Ambient Air TechniquesAmbient Air Techniques

Ratios Source Reconciliation

– semi-volatile PAHs GRACE/SAFER

– Derives source profiles– Requires large VOC dataset

GRACE/SAFERGRACE/SAFER Graphical Ratio Analysis for Composition Estimates

– Define limits of species ratios

Source Apportionment by Factors with Explicit Restrictions– Multivariate receptor model– GRACE and nonnegative source compositions

Henry et al. (1994)– 1990 Atlanta Ozone Precursor Study– 62% tailpipe exhaust– 15% whole gasoline evaporation– 4% headspace vapor

Fuel-Based InventoriesFuel-Based Inventories

Requirements– Fuel sales, relative fuel economies

– CO/CO2 and HC/CO2 measurements

– VOC/CO and NOx/CO correlations

Limitations– Stabilized exhaust only

– Regional inventory only

Singer and Harley (1996)– CO agrees with MVEI 7G

– 58% of CO from cars and trucks > 10 years

Tunnel/Roadway StudiesTunnel/Roadway Studies

Caldecott Tunnel (San Francisco)– Effects of oxygenated gasoline– Effects of reformulated gasoline

PM10/PM2.5 Studies– University of California at Davis– University of California at Riverside– Highways not a PM source

Aloft Measurement StudiesAloft Measurement Studies 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

Manned Balloon– U.S. Air Force

• 250 kg payload250 kg payload• ozone, NOx, VOC samplingozone, NOx, VOC sampling

Aircraft– SCOS97-NARSTO

• 4 aircraft4 aircraft• ozone, NOx, NOy, CO, VOC samplingozone, NOx, NOy, CO, VOC sampling

Remote Sensing StudiesRemote Sensing Studies

Roadway– Remote Sensing Device– CO, “HC”, NOx

Area Source– University of California at Davis

Volume Source– Duke Forest, North Carolina– Texas petroleum refinery

RecommendationsRecommendations

Release tracer gas(es) Measure CO and CO2

Evaluate source profiles with GRACE/SAFER

Timing of emissions is a critical factor in ozone formation