Re-evaluating effectiveness of vehicle emission control programmes targeting high-emitters

Estimating emission distribution within a vehicle fleet is critical for air pollution control. Previous studies reported that more than half of total fleet emissions were produced by only the highest 10% emitters, making repairing or deregistering a small percentage of high-emitters the most cost-effective measure to control vehicle emissions. With diesel emissions data from chassis dynamometer testing and on-road remote sensing, we show that such a strategy may be oversimplified. Accurate estimates of emissions distribution in a vehicle fleet can help air pollution control. With diesel emissions data from chassis dynamometer tests and on-road remote sensing, this study shows that previous results about a skewed distribution towards the highest 10% emitters may not be correct.