Research Projects

Project at a Glance

Project Status: complete

Title: Construction of a DOAS instrument for installation at CARB for the low level measurement of SO2 to investigate the relation between SO2 and sulfate

Principal Investigator / Author(s): Durbin, Thomas

Contractor: UC Riverside

Contract Number: 10-312

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels


Sulfur is an important component of combustion and lubricant-derived particles. Sulfate levels in vehicle exhaust particulates can be readily measured, but it is important to understand the relative contribution between combustion and oil-derived particles and conversion rates of sulfur dioxide (SO2) to sulfate. Current instruments are not capable of measuring the very low sulfur dioxide concentrations typical of new vehicles. The objective of this research is to construct, test, and provide to ARB laboratories a differential optical absorption spectrometer (DOAS) that can measure down to 10 ppbV in real time and determine a mass balance between SO2 and sulfate. Training for ARB's technical staff will also be provided as part of this program so they can run this state of the-art instrument independently. This instrument will open testing possibilities for ARB to understand the workings of advanced catalyzed aftertreatment systems and their interactions with the fuel/lube systems, and the potential of those systems to attenuate or produce sulfate PM. This understanding will help ARB understand the impacts of current emission control policies and guide the development of policies to obtain further reductions.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

Stay involved, sign up with ARB's Research Email Listserver