Renewable Diesel's Impact on Air Quality Examined

Ohio State professor to discuss findings on nitrogen oxide levels along California highways

Apr. 8, 2026 at 4:26am

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A highly structured abstract painting in soft earth tones, featuring sweeping geometric shapes, concentric circles, and precise botanical spirals, conceptually representing the complex interplay of renewable diesel, truck traffic, and nitrogen oxide emissions along California's transportation corridors.An abstract visualization of the environmental impacts as renewable diesel has become the dominant fuel source for California's highways.Davis Today

Gabriel Lade, an associate professor at Ohio State University, will present research on how the rise in renewable diesel use in California has impacted nitrogen oxide (NOx) pollution levels along the state's highway corridors. Lade's talk, "Does Renewable Diesel Clean the Air? Evidence from California Highways," will be part of a spring seminar series hosted by Penn State's Initiative for Energy and Environmental Economics and Policy.

Why it matters

As renewable diesel has grown to make up over two-thirds of California's diesel fuel pool in recent years, driven by state and federal policies, understanding the air quality impacts of this transition is crucial. Lade's research aims to quantify whether the increased use of renewable diesel has led to detectable changes in NOx pollution, which is a key contributor to smog and other air quality issues.

The details

Lade's research used traffic flow data and roadside air quality measurements, along with satellite nitrogen dioxide readings, from 2016 to 2024 to estimate the effects of rising renewable diesel adoption on NOx levels along major California highway corridors. By looking at variations in truck traffic during high-trucking hours and the statewide increase in renewable diesel's market share, the study found evidence that NOx pollution decreased as renewable diesel use grew, with the effects most pronounced during the period of highest adoption.

  • Lade's talk will take place on Wednesday, April 15, 2026 at noon.
  • The research analyzed data from 2016 through 2024.

The players

Gabriel Lade

An associate professor and C. William Swank Chair in Rural-Urban Policy at Ohio State University, who will be presenting research on the air quality impacts of renewable diesel use in California.

Initiative for Energy and Environmental Economics and Policy (EEEPI)

A University-wide initiative at Penn State that is hosting the spring seminar series where Lade will present his findings.

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What they’re saying

“Renewable diesel is a hydro-processed, drop-in replacement for petroleum diesel. In 2011, it accounted for less than 1% of California's diesel pool but in 2024, it increased to more than two-thirds of the pool, largely driven by the state's Low Carbon Fuel Standard and federal renewable fuel incentives.”

— Gabriel Lade, Associate Professor, Ohio State University

“Exploiting variation in truck traffic during high-trucking hours on major freight corridors interacted with the statewide rise in renewable diesel's market share, we find evidence that NOx pollution decreased as renewable diesel adoption increased. The effects appear concentrated in the period of highest adoption and are consistent with nonlinear impacts of large-scale fuel composition change.”

— Gabriel Lade, Associate Professor, Ohio State University

What’s next

Lade's findings on the air quality impacts of renewable diesel use will be of interest to policymakers, regulators, and the transportation industry as they continue to evaluate the role of alternative fuels in reducing emissions.

The takeaway

This research provides important insights into how large-scale shifts in fuel composition can lead to measurable improvements in local air quality, highlighting the potential benefits of renewable diesel as a cleaner alternative to traditional petroleum-based diesel.