Bringing Real-World Vehicle Emissions Data into Emissions Models for Cleaner Air

Crane operator cab, with one man inside and two others standing right outside, as part of an in-use emissions and activity measurement study

Project Brief

The Challenge

As the Volkswagen emissions “cheating” scandal demonstrated, it is crucial to confirm that vehicles and their engines perform as cleanly and efficiently in the real world as they do in the laboratory. Only with this confirmation can agencies know that vehicle emissions standards are being met. Real-world vehicle monitoring is the most reliable way to do this.

ERG's Solution

ERG is a national leader in real-world emissions monitoring. We have supported the U.S. Environmental Protection Agency for more than a decade by conducting in-use emissions and activity measurement studies involving on-road light-duty vehicles, heavy-duty drayage trucks, and nonroad construction equipment. We routinely characterize tailpipe emissions, as well as emissions from subsystem sources such as evaporative hydrocarbon emissions and brake and tire-wear particulate matter emissions. For tailpipe emissions and vehicle activity characterization, our mobile source engineers use portable emissions measurement systems (PEMS) and activity monitoring systems (PAMS) to gather emissions and activity data from vehicles and non-road equipment as they are driven and used in representative operations. This captures effects that are difficult to simulate in the laboratory, such as driving patterns, wind and ambient temperature, road grade, and on-road engine loads from passengers, cargo, and trailers, among other factors. Our engineers rigorously review, validate, classify, and analyze these data, which subsequently feed national and regional emissions models, helping to make them more precise. In this way, the results of real-world vehicle monitoring studies give EPA, states, and other air quality agencies powerful planning tools to estimate regional emissions and develop strategies for achieving clean air goals.


U.S. Environmental Protection Agency