The goal of this project is to develop novel sensing chemistry to rapidly assess the ability of freshly collected atmospheric aerosols to cause oxidative stress in biological systems. We propose to design and validate of a novel sensor for oxidative load that combines advantageous aspects of microfluidics with a new aerosol collection system. We hypothesize that measurement of direct and indirect oxidative load from freshly collected aerosol particles can be achieved using a microfluidic sensor coupled to an aerosol particle collector. Our approach is to replace traditional measurement instrumentation (filter collection with chromatography/spectroscopy) that is bulky, expensive, and slow with sensing systems utilizing microfluidics that are compact, fast, and inexpensive. Microfluidics provides the ability to carry out the chemical reactions necessary to determine oxidative load without repeated manual steps and provide the analytics to measure the resulting signals using microliter solution volumes. This reduction in solution volume allows a dramatic reduction in sampling and analysis time while still generating a measurable signal. The small size of the microfluidic system will also allow a portable sensor to be created, with the potential for personalized exposure assessment. At the same time we measure the reactivity of these aerosols, we will use on-line aerosol mass spectrometry to provide additional information on the relationship between oxidative load and the composition, size, and age of atmospheric aerosol. The aims of this project are: Specific Aim 1: Design, build, and test a microfluidic sensor coupled to a particle collector for measurement of aerosol oxidative load. In this design-focused aim, we will create the new sensing chemistry required for measurement of direct and indirect oxidative load. We will also evaluate analytic limits of detection and quantification under controlled laboratory conditions. Specific Aim 2: Measure the direct and indirect oxidative loads of freshly collected atmospheric aerosols. In the second aim we will test our central hypothesis, the ability to measure oxidative load of freshly deposited aerosol particles. We will also evaluate aspects of method sensitivity and specificity using alternative, off-line chemical analyses. PUBLIC HEALTH RELEVANCE: An emerging hypothesis states that aerosols cause a majority of their harmful effects by eliciting cellular oxidative stress. Consequently, there is a need for advancement in the field of oxidative stress measurement related to environmental agents. A novel on-line monitoring tool that provides a more physiologically relevant measure of air pollution properties that correlate with human disease will support benchside, sub-clinical, nd population-level studies that seek to associate oxidative air pollution with human disease. Thus, this instrumentation will help researchers and policymakers better understand the sources and mechanisms by which air pollution induces adverse health outcomes in both healthy and at-risk populations.