To meet requirements for improved efficiency and reduced emissions, a large number of new vehicle fuels and technologies are being developed. Although there is opportunity for major progress, HEI is interested in identifying any potential unintended health consequences from such developments. HEI’s Communication 16, The Future of Vehicle Fuels and Technologies: Anticipating Health Benefits and Challenges, published by the Scientific Committee on Emerging Technologies (SCET) in 2011, provides a comprehensive perspective on these issues.
Internal combustion gasoline and diesel engines, improved for efficiency and emissions, are likely to continue to play a major role for at least the next 10 years in the transportation sector. HEI’s work has focused on several aspects of diesel and gasoline engines and their emissions.
In view of the hazards from exposure to emissions from diesel engines, EPA and regulatory agencies in other countries have promulgated stringent regulations during the last 10 years. In response, truck and automobile engine manufacturers have made significant improvements in the design of such engines and after-treatment systems. HEI undertook a major program, the Advanced Collaborative Emissions Study (ACES), with the goal of (a) detailed characterization of emissions from heavy-duty (truck and bus) diesel engines compliant with the EPA’s 2007 and 2010 regulations; and (b) assessment of health effects in rodents exposed to NTDE from a 2007-compliant engine. The reports of these studies have been published. Please refer to the ACES Executive Summary for links to all reports.
To address the some of the other questions and challenges identified in Communication 16, HEI has also investigated emissions, exposure, and health effects data on ultrafine particles (see Perspectives 3).
In addition, occasionally HEI has funded studies to evaluate exposures in real-world situations that provide information on emissions from the current vehicle fleet that can be compared to previous assessments of older fleets (see tunnel studies by Gertler and Grosjean, or on detailed measurement of ultrafine particles (see the study by Johnston). Currently, HEI is funding a study to measure pollutant levels at two tunnels (by Wang). Also, as the contribution of diesel emissions to ambient particulate matter goes down, the importance of other sources of particulate matter – such as brake and tire wear – increases; HEI is funding a study in the Boston area to investigate these issues (by Koutrakis).
Another issue discussed in Communication 16 relates to the deployment of gasoline direct injection (GDI) technology. GDI improves fuel efficiency, but such engines also emit increased amounts of particulate matter in the ultrafine range. To understand the potential impact of emissions from GDI engines, HEI anticipates holding a workshop during 2017 or 2018. Details will be posted at a later date.
The investigators are characterizing contributions to ambient particles released directly (tailpipe and non-tailpipe emissions) and indirectly (resuspended road dust). They will identify variables that may influence the emissions, using a mobile sampling platform to collect particle samples in the Greater Boston area.
This study is characterizing vehicle emission in two tunnels with different proportions of diesel and gasoline vehicles, measuring fleet average emission factors for a number of pollutants and comparing the results to previous tunnel studies.