Oxygen therapy is an essential treatment for patients with coronavirus disease 2019, although there is a risk of aerosolization of additional viral droplets occurring during this treatment that poses a danger to healthcare professionals. High‐flow oxygen through nasal cannula (HFNC) is a vital treatment bridging low‐flow oxygen therapy with tracheal intubation. Although many barrier devices (including devices without negative pressure in the barrier) have been reported in the literature, few barrier devices are suitable for HFNC and aerosol infection control procedures during HFNC have not yet been established. Hence, we built a single cough simulator model to examine the effectiveness of three protective measures (a semi‐closed barrier device, a personalized exhaust, and surgical masks) administered in isolation as well as in combination using particle counter measurements and laser sheet visualization. We found that the addition of a personalized exhaust to a semi‐closed barrier device reduced aerosol leakage during HFNC without negative pressure. This novel combination may thus reduce aerosol exposure during oxygen therapy, enhance the protection of healthcare workers, and likely reduce nosocomial infection risk.