Project Summary Through this SBIR project, we aim to develop new methods and technologies for monitoring personal exposure to polycyclic aromatic hydrocarbons (PAHs). Because PAHs cause DNA damage that may initiate cancer, these compounds pose considerable risk to human health. Chronic exposure to PAHs in the workplace has been associated with increased risk of cancer for firefighters, road construction workers, roofers and vehicle operators. To identify and assess worker exposure to airborne PAHs, industrial hygienists utilize sorbent tubes. However, this method has significant disadvantages including high-cost, burdensome sampling and handling, low accuracy and delayed reporting due to required analysis by an external laboratory. Thus, there exist an unmet need for new methods for monitoring exposure to PAHs. This project aims to develop simple, low-cost, wearable dosimeters sampling badges that provide real-time and accurate monitoring of exposure to airborne PAHs. This work builds on exciting preliminary results that demonstrate that films of liquid crystals (LC) exhibit an abrupt optical transition when exposed to PAHs, but not when exposed to other gaseous chemicals. In Phase I, we will use hypothesis-based testing to develop a better understanding of materials and design considerations to guide the development of LC-based dosimeters for measuring exposure to PAHs. We aim to (i) understand the material properties that influence the response of LC films to PAHs with the goal of optimizing sensitivity, and (ii) identify dosimeter configurations that enable quantitative measurements of the concentration of PAHs in air. The outcomes of this work will provide design principles for fabricating dosimeter sampling badges for quantitative characterization of exposure to PAHs in the workplace. More broadly, the tools and methods developed through these efforts will enable new assessments on worker exposures to PAHs, and this new knowledge may lead to actions that reduce occupational cancer and other adverse health outcomes, and create safer workplaces. Thus, the goals of this SBIR project are well alight with the NIOSH Priority Goals for Extramural Research for 2019-2023.