Investigate the Durability of Diesel Engine Emissions Controls

This page last reviewed April 3, 2015


Introduction of new engine emissions standards for particulate matter (PM) and oxides of nitrogen (NOx) will result in a substantial decrease of these pollutants over the course of the next several years. This reduction is achieved by using devices such as diesel particulate filters (DPF) and selective catalytic reduction (SCR). Recently revised ARB fleet rules will lead to gradual introduction of newer engines on California highways and ports thereby reducing emissions from diesel engines.

The technology used to reduce PM and NOx in the newer trucks include DPF and SCR respectively. While various studies have been performed to assess the efficiency of these devices (some of which were funded by ARB), so far minimal data exists on the durability and deterioration of these devices. The primary reason for limited data includes fairly recent introduction of these devices along with challenges related to sampling thousands of trucks over a course of multiple years. The available data is also sparse in terms of PM measurement and has often utilized technologies that don’t measure PM directly. In essence, while the available data can provide emission changes, (to an extent), due to improvement in engine technology, it falls short in providing a good understanding of emission changes related to introduction of aftertreatment devices (for an extended period of time). Undertaking a project to measure pollutant concentrations in the real world is important as without fully functioning aftertreatment devices, these trucks could emit tens to hundreds of times higher emissions than a truck meeting certification standards. Potential aftertreatment failures and related emissions increases would reduce the air quality and health benefits of the new engine standards and also generate inaccurate emission inventories. Additionally, such a study may also provide clues about tampering/mal-maintenance of these devices that could cause increase in pollutant concentrations.

This project will build upon existing databases of on-road measurements (remote sensing, vehicle chase studies, etc.), to provide a comprehensive analysis of pollutant profiles over the course of several years. The sampling of heavy-duty fleet is being performed at the Port of Los Angeles and at a California Highway Patrol (CHP) inspection facility in Cottonwood, CA in 2013, 2015 and 2017. Data includes measurements of criteria pollutants, such as carbon monoxide, total hydrocarbons, NOx, and PM as well as nitrogen oxide, nitrogen dioxide, and black carbon at a minimum. Particle number and size distribution would be valuable additional measurements.


Peer-Reviewed Publications

Conference Presentations

  • Rachel Hottor-Raguindin et al. (2014). Heavy Duty Diesel Vehicle Emissions Collected Using the On-Road HDDV Monitoring System (OHMS). 24rd CRC On-Road Vehicle Emissions Workshop, March 30 – April 2, 2014, San Diego, CA. Slideshow (PDF, 1.57 MB)
  • Donald Stedman et al. (2015). HDDV Emissions Measurements as We Speak. 25th CRC On-Road Vehicle Emissions Workshop, March 22-25, 2015, Long Beach, CA. Poster (PDF, 769 kB)