Engine, aftertreatment, fuel quality and non-tailpipe achievements to lower gasoline vehicle PM emissions: Literature review and future prospects

• Published in: The Science of the total environment 2023-03, Vol.866, p.161225-161225, Article 161225
• Main Author: Maricq, M. Matti
• Format: Article
• Language: English
• Subjects: Brake & tire emissions; Gasoline vehicle; PM emissions; Soot; Transportation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.161225

Spark ignition gasoline vehicles comprise most light duty vehicles worldwide. These vehicles were not historically associated with PM emissions. This changed about 15 years ago when emissions regulations forced diesel engines to employ exhaust particulate filters and fuel economy requirements ushered in gasoline direct injection (GDI) technology. These shifts reversed the roles of gasoline and diesel vehicles, with GDI vehicles now regarded as the high PM emitters. Regulators worldwide responded with new or revised PM emissions standards. This review takes a comprehensive look at PM emissions from gasoline vehicles. It examines the technological advances that made it possible for GDI vehicles to meet even the most stringent tailpipe PM standards. These include fuel injection strategies and injector designs to limit fuel films in the engine cylinder that were pathways for soot formation and the development of gasoline particle filters to remove PM from engine exhaust. The review also examines non-exhaust PM emissions from brake, tire, and road wear, which have become the dominant sources of vehicle derived PM. Understanding the low levels of GDI tailpipe PM emissions that have been achieved and its contribution to total vehicle PM emissions is essential for the current debate about the future of internal combustion engines versus rapidly evolving battery electric vehicles. In this context, it does not make sense to consider BEVs as zero emitting vehicles. Rather, a more holistic framework is needed to compare the relative merits of various vehicle powertrains. [Display omitted] •Detailed analysis of engine technology advances that reduce PM emissions.•Assessment of gasoline particulate filter capability to achieve ultra-low PM emissions.•Examination of the particulate matter index and fuel effects on gasoline vehicle PM.•Analyses of brake, tire and road wear PM emissions.•Comparison of total vehicle PM emissions from gasoline versus battery electric vehicles.