IDENTIFICATION OF HIGH-EMITTING CATALYST CARS ON THE ROAD BY MEANS OFREMOTE-SENSING

Repeated remote sensing measurements were carried out at a site outsid e Stockholm, Sweden, in 1995, to investigate the ability of a remote s ensor to identify catalyst cars on the road with excess emissions. Ten catalyst cars were selected from the measurements for a chassis dynam ometer and service/repair study. The results show that average remote sensor CO readings based on repeat measurements can be used to fairly accurately predict CO and HC emissions, but not NOx emissions, from ca talyst cars over a full driving cycle. Furthermore, it was demonstrate d that low-cost service and repair of high-emitting catalyst cars may reduce CO and HC emissions by more than 90% and fuel consumption by up to 20%, whereas NOx emissions tended to increase. The study indicates that the fraction of catalyst cars with excess FTP emissions in Swede n in 1995 was about 10% as regards CO and about 3% as regards HC, and that the 'super-emitter' fraction was about 0.5%. Despite the small fr actions, these categories may account for a significant share of catal yst cars' overall CO and HC emissions.