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Sunday, May 4 - Tuesday, May 6, 2025 at the Austin Marriott Downtown Hotel in Austin, Texas.

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Home > Air Pollution

Diesel Exhaust

Diesel engines are a key part of the world’s transportation and industrial infrastructure, especially in heavy-duty applications. Despite the durability and efficiency of diesel engines, there have long been concerns about the environmental and human health impacts of diesel engine emissions, which include fine particulate matter (PM2.5), nitrogen oxides (NOx), and hydrocarbons (including some carcinogens). As part of its founding mission, HEI research has evaluated exposure and health effects in the ever-changing landscape of diesel engine emissions.

Heavy-duty truck

HEI reviews related to health effects of diesel emissions have included

  • Assessments of the carcinogenicity of diesel exhaust (HEI 1995, HEI 1999; HEI Diesel Epidemiology Panel 2015)
  • A report by HEI’s Special Committee on Emerging Technologies (SCET) that described how new fuels and engine technologies would likely affect emissions, air quality, and potential health effects (Communication 16),
  • A systematic review and meta-analysis of epidemiological studies on long-term health effects from exposure to traffic-related air pollution (HEI 2022)

HEI has also funded and published research documenting emissions benefits of newer diesel technologies, including the following:

  • A study documenting the substantial improvements that can result from using emissions control technologies, including diesel particulate filters and selective catalytic reduction for heavy-duty diesel engines (Advanced Collaborative Emissions Study [ACES])
  • A study on the effectiveness of goods movement actions in California to improve air quality and health outcomes (Meng et al. 2021)

As of 2022, more than a third of the fleet of trucks and buses on the road did not have the newest technologies to reduce PM and NOx emissions. As the fuels and technology powering our transportation continue to evolve, HEI has assembled a panel of highly respected scientists to evaluate how replacing the oldest diesel engines in operation in the United States with cleaner technologies could reduce emissions to benefit air quality and human health.

For more information, please contact Allison Patton at HEI.

    HEI Panel on Heavy Duty Diesel Fleet Turnover
    Marianne Hatzopoulou
    Marianne Hatzopoulou, Ph.D., Professor, Civil and Mineral Engineering, University of Toronto; Canada Research Chair in Transport Decarbonization and Air Quality
    Kanok Boriboonsomsin, Ph.D., P.E. Research Engineer and Associate Director at CE-CERT, UC Riverside
    jane lin
    Jane Lin, Ph.D., Professor, University of Illinois Chicago
    Deb Niemeier
    Deb Niemeier, P.E., Ph.D., NAE Clark Distinguished Chair in Energy and Sustainability and Professor, University of Maryland
    Tara Ramani
    Tara Ramani, Ph.D., P.E. Research Engineer and Division Head - Air Quality, Energy, and Health and Deputy Director - Center for Advancing Research in Transportation Emissions, Energy and Health, Texas A&M Transportation Institute
    Christopher Tessum
    Christopher Tessum, Ph.D., Assistant Professor, University of Illinois at Urbana−Champaign