We have a couple of projects underway evaluating the sensitivity of ozone “smog” to its two main ingredients: NO_x and VOCs. Past work in our group has used satellite data for this problem in China [Jin and Holloway, 2014], and reported on past work using this metric for decision-making in the state of Colorado [Witman et al., 2014]. Now, we are applying this metric across cities in the U.S., and find that the bigger the city, the more sensitive it is to VOC emissions. We are using this satellite data ratio to evaluate the skill of a widely used air quality model run by our collaborators at the Lake Michigan Air Director’s Consortium (LADCO). We are also investigating the way NO₂ changes throughout the data across the U.S., comparing ground-based monitors with two different NO₂ satellite retrievals (OMI and GOME-2).