Test bed studies require Chemistry of Indoor Environment researchers to be able to make important indoor chemistry measurements quickly and at low cost. Unfortunately, there are no good low-cost sensors for volatile organic compounds (VOCs). This grant funds an effort to build one. It’s an important effort. Many VOCs are harmful to human health and even those that aren’t can react with oxidants, eventually leading to new particle and aerosol formation. Over the next three years, Jesse Kroll—Associate Professor of Civil and Environmental Engineering and Associate Professor of Chemical Engineering at the Massachusetts Institute of Technology—will attempt to develop a low-cost monitor for measurements of volatile organic compounds in the indoor environment. The work plan has two major parts: the construction, characterization, and optimization of the VOC monitor, and the use of several such monitors in real indoor environments, providing both a proof-of-concept and initial measurements of indoor VOC levels. The primary output of this project will be the monitor and associated algorithms as well as the associated research results. Descriptions of the optimized monitor design and calibration algorithms will be disseminated broadly via the peer-reviewed, open-access literature and conference presentations. At least one graduate student will be trained.