Building energy consumption accounts for forty percent of energy consumed in the United States, but this energy consumption can be mitigated through building weatherization, which reduces the leakage flow of indoor air. This study aims to ascertain the effects of weatherization onto indoor air quality. The study measures key physical parameters associated with air quality, including particle number concentrations, particle mass concentrations, and indoor air radon levels, in five homes (three control homes, two case homes) in Ithaca, New York. The homes were sampled twice - pre-weatherization in the fall and winter of 2013, and post-weatherization in the spring of 2014. The results show that the weatherization process caused a decrease in the air exchange rate in the weatherized case homes, but the limited sample size makes it difficult to come to conclusions about indoor air quality trends.