To date over 750,000 homes have been weatherized in the U.S. Department of Energy's Weatherization Assistance program to help homeowners make their homes more energy efficient. Some of the energy efficient upgrades-such as sealing ducts and installing more efficient windows-reduce the levels of ventilation in homes, resulting in changes that could influence the size, composition, location, or diversity of microbial communities inside the home. Funds from this grant support a two-year pilot study by Largus Angenent, associate professor in of biological and environmental engineering at Cornell University to investigate and characterize how weatherization changes in indoor airborne microbiota of homes. Angenent will study fifteen homes in the Finger Lakes region of New York State, sampling the air both inside and outside a home immediately before it is weatherized, directly after weatherization is completed, and again six months later. Analysis of the collected samples will provide preliminary data that suggest how weatherization changes microbial communities and, depending on results, could form the basis for further data collection and research by the U.S. Department of Energy or some other federal agency.