Multi-year remote-sensing measurements of gasoline light-duty vehicle emissions on a freeway ramp

On-road optical remote-sensing measurements of gasoline light-duty vehicle (LDV) emissions - CO, HC, NO - were conducted on a freeway ramp in Gothenbu rg, Sweden, in 1991, 1995 and 1998. Based on almost 30,000 emission measure ments, the results show that both catalyst cars and non-catalyst cars emiss ions deteriorate over time, but also that the emission performance of new T WC-cars has improved significantly in recent years. Furthermore, it was fou nd that fleet age rather than model year determines the rate of emission de terioration for TWC-cars for both CO and NO. The study demonstrates that re mote sensing may constitute a powerful tool to evaluate real-world LDV emis sions; however, daily held calibration procedures need to be developed in o rder to assure that the evolution in fleet average emissions can be accurat ely measured. (C) 2000 Elsevier Science Ltd. All rights reserved.