Oregon DEQ’s Non-road Diesel Emission Inventory

The Oregon Department of Environmental Quality (DEQ) has issued the final Oregon Nonroad Diesel Equipment Survey and Emissions Inventory, completed with the help of Eastern Research Group, Inc. (ERG); Good Company LLC; and Oak Leaf Environmental, Inc. The aim of this study was to generate Oregon-specific data of non-road equipment characteristics, such as: engine age, activity rate, fuel consumption, and geographic distribution.

A non-road vehicle is defined as any vehicle not designated for travel on major roadways, such as tractors, front end loaders, bulldozers, and cranes. Prior to this study, DEQ and other agencies relied heavily on the national default data supplied by the U.S. Environmental Protection Agency (EPA) because non-road vehicles are not tracked in a registration-based system as on-road vehicles are. 

One key finding from this study is that non-road vehicles in Oregon are, on average, older but are used less than what was previously believed. Reflecting the tighter engine emission standards over time, older equipment has a higher emission rate, in some cases ten times or more, and thus higher emissions. However, that factor coupled with less activity resulted in similar total statewide emissions of atmospheric fine particulate matter (PM) with a diameter of less than 2.5 micrometers. Drilling down the data, emissions varied at a county scale and for particular sectors (such as agriculture). 

Oregon is only the third state in the country to have contracted a study to better understand the impact of non-road equipment on air quality. The results from this study can enable us to better predict emissions from non-road engines when running a transportation emissions model, such as the EPA’s MOtor Vehicle Emission Simulator (MOVES). These Oregon-specific data can be used as input files in the MOVES model, allowing for more accurate and representative emission results. 

Fortunately for Air Sciences and its clients, Lyndsey Boyle, a recent Data Analyst hire, was an Emissions Inventory Specialist at Oregon DEQ, providing direct support for this study. Her background in diesel and transportation-related emissions and technical experience with EPA’s MOVES model adds additional expertise to our diverse team of air quality professionals.

For the full report and the presentation of the final report, please visit the Oregon DEQ website.

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