A Critical Review of the Effectiveness of I/M Programs for Monitoring PM Emissions from Heavy Duty Vehicles

Abstract

Heavy-duty vehicles (HDV) are estimated to contribute up to 36% of particulate matter (PM) emissions in urban areas. In response, many agencies have established HDV inspection and maintenance (I/M) programs designed to target and repair vehicles with excess emissions. In this review, we conduct an international comparison of legislative context and HDV I/M program characteristics across Europe, North America, and Australia. The results of this analysis show that HDV-I/M programs vary greatly in terms of the ways in which testing is organized, for example, roadside versus periodic testing, whether the fleet is self-tested, and how nonfleet and age exemptions are handled. We also show how the I/M test criteria have changed little in the last 15 years while regulations for new heavy-duty diesel engine emissions have become increasingly stringent. In the U.S., HDV engine PM emissions limits were reduced by a factor of 26 between 1997 and 2007. Most I/M programs have continued to test according to EPA (and often with state legislative confirmation) guidance procedures having cut-points established in 1992. An analysis of data from Washington State show that only a minority of post-1997 vehicles actually exceeds the detection levels of the free-acceleration smoke-opacity test procedures, with the result that malfunctions of these vehicles may not actually be detected. From our review, it is clear that even with the potential adoption of new technologies and a more systematic and efficient framework for HDV-I/M, more research must be conducted in the efficacies of periodic versus roadside testing (and location selection), the use of evaluation methods like fail rates and opacity distributions, and finally, in development of better methods for identifying excess emissions with sensors and duty cycles.

Hierarchical Ceramic Foams with 3D Interconnected Network Architecture for Superior High-Temperature Particulate Matter Capture

“…1−3 PM can easily penetrate into human respiratory track; therefore, long-term exposure to PM pollution will lead to many health problems. 4,5 To tackle this issue, porous and fibrous membranes have been successfully proposed and widely used to capture these high-temperature PMs. 6−8 Nevertheless, these materials still possess critical challenges such as low efficiency, large pressure drop, poor thermal stability, and high production cost, which critically hinder their widespread applications.…”

“…High-temperature particulate matter (PM), mostly emitted from coal-fired industries, such as power plants, metallurgic industries, and biomass gasification plants, has become a major environmental problem. − PM can easily penetrate into human respiratory track; therefore, long-term exposure to PM pollution will lead to many health problems. , To tackle this issue, porous and fibrous membranes have been successfully proposed and widely used to capture these high-temperature PMs. − Nevertheless, these materials still possess critical challenges such as low efficiency, large pressure drop, poor thermal stability, and high production cost, which critically hinder their widespread applications. Therefore, it is essential to develop new filters for high-temperature PM.…”