We evaluated a full-face snorkel mask with an airway circuit filter to protect health care providers against airborne pathogens. First, a quantified N95 fit test was performed using aerosolized saline. Second, cardiorespiratory variables (heart rate, peripheral oxygen saturation, end-tidal carbon dioxide tension, and inspired fraction of carbon dioxide) were measured at rest and during moderate exercise. The modified mask passed the United States Occupational Safety and Health Administration (OSHA) N95 respirator (N95) fit test requirements with a fit factor of 142. Neither hypercapnia nor hypoxemia occurred. This modified mask has the potential to protect providers who care for patients with coronavirus disease 2019 (COVID-19).