Measurements of automobile exhaust using the LasIR tunable diode laser spectrometer system

Remote sensing measurements of CO to CO 2 ratios, and hence the CO emissions from on-road vehicles are being made in Houston and Dallas metropolitan areas in the state of Texas. A near infrared tunable diode laser absorption spectrometer system integrated with License Plate Recognition, speed and acceleration measurement systems, as been used to monitor over 345,000 vehicles in the first six months at the end of 1998 and beginning of 1999. About 1.5% of the vehicles were found to be gross emitters (emitting more than 6% CO) and about 12% of the vehicles were determined to be high emitters (emitting between 2% and 6% CO). Some 73% of the vehicles emitted less than 1% CO. Five percent of the vehicles generated approximately 26% of the CO emissions. The next fifteen percent of the vehicles generated another 34% of the CO emissions. The fraction of high emitters had a small linear increase with the age of the vehicle up to 1990 model year and a relatively rapid increase for older vehicles.