Gentrification is associated with factors that negatively impact health outcomes among low-income households, but few studies have explored its correlation with disease rates. In this study, we assess the relationship between increased levels of gentrification and the rate ratio of asthma exacerbations in nine counties within the San Francisco Bay Area. We conducted an ecological study of gentrification levels and asthma exacerbations in nine San Francisco Bay Area counties. Measures of gentrification were calculated with the Freeman, et al. method, using data from the 2006-2015 American Community Survey to classify median income and educational attainment per census tract. The census tract-level population-level ageadjusted rate of emergency department (ED) visits for asthma was obtained from the CalEnvironScreen 3.0. The association between gentrification levels and asthma exacerbations was modeled with population weighted log-linear regression. An adjusted model with potential confounding variables from the CalEnviroScreen 3.0 were added to the adjusted model, including the percentage of adults with less than high school education (labeled as educational attainment), traffic emissions, particulate matter (PM 2.5), toxic factory emissions, diesel exhaust emissions, and pollution burden. The unadjusted rate ratio of ED visits for asthma when comparing gentrifying to stable neighborhoods was 1.29 (95% CI 1.27-1.31, p < 0.001) for the aggregate of all nine San Francisco Bay Area counties. After adjustment for educational attainment and five pollution measures, the rate ratio was 1.15 (95% CI 1.13-1.17, p < 0.001). Tests for effect modification between percentage racial composition and levels of gentrification found that gentrifying census tracts with higher racial segregation for Blacks, Hispanics, and Asians had lower adjusted rate ratios of ED visits for asthma (Blacks: 0.97, 95% CI 0.83-1.13, p = 0.7, Hispanics: 0.84, 95% CI 0.81-0.88, p < 0.001, Asians: 0.86, 95% CI 0.81-0.9, p < 0.001). Living in a gentrifying neighborhood was associated with an increased rate ratio of asthma in the nine county San Francisco Bay Area. Our results were consistent with prior studies suggesting a differential effect of gentrification on health outcomes by racial composition in the neighborhood. However, it is unclear whether this is a reflection Extended author information available on the last page of the article SN Soc Sci (2022) 2:3