Clearing the Kitchen Air angetop cooking produces, among other things, water vapor, grease, smoke, and cooking odors. In addition, gas ranges produce nitrogen dioxide, carbon monoxide, and carbon dioxide. Left in the house, these gases pose health risks, while moisture poses the usual risk to the house itself. For all these reasons, most new and remodeled kitchens these days have some sort of ventilation. But some of these units aren't up to the task before them, and fail to remove moisture and contaminants. Here at the University of Minnesota, we tested the two main types of kitchen exhaust systems, overhead range hoods and downdraft fans, to see how well they capture cooking contaminants. We used steam from boiling water to simulate the exhaust