Emission Measurement and Management in Road Vehicles

Road transport remains a major source of greenhouse gases and urban air pollutants, prompting continuous advances in both measurement techniques and management strategies. Emission measurement has evolved from standardised laboratory dynamometer cycles to on-road systems that capture real-world driving conditions, fuel use and pollutant release. Portable emission analysers, remote sensing and data-driven methods now enable high‐resolution tracking of carbon dioxide, nitrogen oxides and particulate matter across diverse vehicle types and operating environments. Management approaches integrate technological solutions—such as selective catalytic reduction, diesel particulate filters and electrification—with policy instruments including real-driving emissions protocols, low-emission zones and life-cycle carbon accounting. Together, these developments support more accurate inventories, targeted mitigation measures and harmonised regulations, thereby reducing health impacts, curbing climate forcing and informing sustainable transport planning worldwide.

Research from Nature Portfolio

Recent work has examined the hidden climate impacts of the international trade in used vehicles. Quantitative analysis of carbon dioxide and pollutant outputs from decommissioned cars exported from high-income regions to low- and middle-income destinations shows that regulatory gaps and poorer maintenance amplify on-road emissions by roughly 13–53 per cent compared with vehicles that are scrapped domestically or retained under local standards. These findings underscore the importance of incorporating cross-border stock turnover into national emissions inventories and highlight the need for harmonised end-of-life policies to deliver genuine air quality and climate benefits throughout a vehicle’s life cycle.

Emission Measurement and Management in Road Vehicles publication trend

The graph below shows the total number of articles in emission measurement and management in road vehicles across all publications each year (not limited to Nature Index journals).

Technical terms

Portable Emissions Measurement Systems (PEMS): On-board analysers that record exhaust pollutant concentrations and engine parameters while a vehicle is driven under real-world conditions.

Real-Driving Emissions (RDE) testing: A regulatory procedure mandating on-road measurements to complement laboratory type-approval tests, ensuring compliance under varied driving scenarios.

Biplot: A graphical representation that displays both variables and samples in a single plot, facilitating the analysis of multivariate data relationships.

Type approval test: Standardised laboratory protocols used to certify vehicle emission limits before market entry.

Nitrogen oxides (NOx): A group of reactive gases, principally nitric oxide and nitrogen dioxide, formed during combustion and contributing to air pollution and health impacts.

References

1. Offshoring emissions through used vehicle exports. Nature Climate Change (2024).
2. A combined framework of Biplots and Machine Learning for real-world driving volatility and emissions data interpretation. Sustainable Cities and Society (2023).
3. Framework for the assessment of PEMS (Portable Emissions Measurement Systems) uncertainty. Environmental Research (2018).
4. Strong Temperature Dependence for Light-Duty Diesel Vehicle NO x Emissions. Environmental Science and Technology (2019).