Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the United States, with 16 million Americans currently suffering from difficult breathing. Power outages could be life-threatening for those relying on electricity. However, significant gaps remain in understanding the potential impact of power outages on COPD exacerbations.Question: How power outages affect COPD exacerbations.Using distributed lag nonlinear models controlling for time-varying confounders, we compared the hospitalization rate during power outage versus non-outage periods to determine the rate ratio (RR) for COPD and its subtypes at each of 0-6 lag days in New York State, 2001-2013. We conducted stratified analyses by socio-demographics, season and clinical severity, and investigated changes in numerous critical medical indicators including length of stay, hospital cost, the number of comorbidities and therapeutic procedures between the two periods.We observed the RR of COPD hospitalization following power outages ranged from 1.03 to 1.39 across lag days. The risk was strongest at lag0 and lag1 days and lasted significantly for 7 days. Associations were stronger for the subgroup with acute bronchitis (RR: 1.08 to 1.69) than for acute exacerbation cases (RR: 1.03 to 1.40). Compared with non-outage periods, the outage period was observed to be $4.67 thousand greater in hospital cost and 1.38 greater in the number of comorbidities per case. The average cost (or number of comorbidities) was elevated in all groups stratified by cost (or number of comorbidities). In contrast, changes in the average length of stay (-0.43 days) and the average number of therapeutic procedures (-0.09 procedures) were subtle.Power outages were associated with a significantly elevated rate of COPD hospitalization as well as greater costs and number of comorbidities. The average cost and number of comorbidities were elevated in all clinical severity groups.