There is growing interest in the use of biodiesel to replace petroleum diesel fuel. Biodiesel has been suggested to pose less risk to human health and the environment. While there is a considerable body of evidence on the negative health effects of petroleum diesel exhaust exposures, there has been little research examining the effects switching to biodiesel may have on worker health and the local environment. In recent years, multiple tailpipe emissions studies have indicated biodiesel use reduces emissions of carbon monoxide, particulate matter, and total hydrocarbons; however it remains unclear if emissions reductions measured at the vehicle tailpipe in a laboratory setting will translate to exposure reductions of particulate matter and other pollutants under conditions of real-world operation. In 2008 U.S. biodiesel production volume expected to approach 600 million gallons. This increase in production has occurred despite a paucity of human exposure and health effects research.

    Recent research in our laboratory demonstrated 20% biodiesel/80% petroleum diesel (B20) use reduced airborne fine particulate matter (PM2.5) exposure concentrations by approximately 60%. Exposure to fine particulate matter is well associated with acute and chronic cardiopulmonary effects, so this observed reduction in particulate matter exposures by use of biodiesel is promising. Conversely, B20 use demonstrated a 370% increase in organic carbon concentrations. However, the chemical nature of these organics has not yet been characterized. Comparative study of the organic fraction of diesel exhaust and exhaust from varying biodiesel/petroleum diesel blends is limited at this time, but will be a focus in this project.       

Although PAH's (polycyclic aromatic hydrocarbons) in biodiesel particulate matter would be expected to be lower (due to lack of aromatic content in pure biodiesel), there is wide variation in PAH levels depending on the feedstock. Changes in particle size and morphology are also critically important to understand biodiesel's overall impact on public health, as decreased mass concentration but smaller particle diameter/increased surface area would be undesirable characteristics. An additional novel aspect of this research is its focus on locally produced biodiesel made from waste yellow and brown grease feedstocks. Most biodiesel tailpipe emissions research has been performed on soy based feedstocks; waste grease emissions are relatively unstudied, yet becoming increasingly popular as companies seek to maximize non-food sources of fuel. It is believed that this is one of the first studies to examine exposure profiles resulting from use of waste grease –based biodiesel.

This project characterizes diesel/biodiesel occupational and environmental exposure profiles in an application utilizing heavy-duty nonroad diesel engines, with a focus on fine and quasi-ultrafine particulate matter exposure. Measurement of 'real world' exposures provides valuable data to evaluate potential health risks to workers and the local public, and is often a weak link in the risk assessment process. We will specifically investigate the hypothesis that controlling the blend percentage of biodiesel (B20 - B50) will result in significant reductions in total PM2.5 mass; significant differences in particle morphology; and significant decreases in highly toxic organic carbon species (PAH's & nitro-PAH's).

Drawing interest from students from a variety of disciplines, the COBRE biodiesel project engages students directly in the research process.

2009-2010 Student Researchers

• Kyle Barnett (Safety Studies)
• Alissa Couturier (Safety Studies)
• Greg Goupil (Safety Studies)
• Ryan Hall (Safety Studies)
• Ben Lazich (Safety Studies)
• Peter Kersker (Safety Studies)
• Dan O'Brien (Safety Studies)
• Anthony Santa Fe (Safety Studies)
• Dustin Sciacca (Environmental Studies)
• Mel Sweeney (Environmental Studies)

2010-2011 Student Researchers

• Alison Dreyfus (Math/Physics)
• Megan Ferm (Chemistry)

2011-2012 Student Researchers

• Taylor Barnes (Environmental Studies)
• Joe Frechette (Safety Studies)
• Drew Grandmont (Safety Studies, Environmental Studies & Philosophy)
• Jeff Pelkey (Safety Studies, Environmental Studies)
• Kristin Bissonette (Chemistry, Biology)
• Sam Guimaraes (Individualized major, Toxicology)
• Connor Tyrrell (Environmental Studies)

Traviss, N., Thelen, B.A., Ingalls, J. and Treadwell, M. 2010. Biodiesel vs. Diesel: A pilot study examining exhaust exposures for employees at a rural municipal facility. Journal of Air and Waste Management 60: 1026-1033.

Traviss, N., Thelen, B.A., Ingalls, J, Treadwell, M. 2011. Evaluation of the impact of biodiesel on occupational and environmental exposure profiles. Journal of Air Quality and Atmospheric Health. Available via: Online first DOI: 10.1007/s11869-011-0141-8.