DISCOVER-AQ is a NASA led Earth Venture Mission which occurred over a 4 year period (2011-2014). The study aimed at improving the use of satellites in air quality characterization. During the last two field campaigns in Houston, TX (September 2013) and Denver, CO (July to August 2014), emerging, low-cost sensor technologies were evaluated alongside other equipment to measure air quality. As communities and individuals have become very interested in these new technologies, citizen scientists were recruited to help collect ground-based air quality measurements using low-cost sensors.