After the outbreak of COVID-19, many dental clinics use dry fogging of hydrogen peroxide (H2O2) to disinfect the air and surfaces. Inhalation of highly concentrated solutions of H2O2 may cause severe respiratory problems. This study aimed to estimate the health risk assessments of inhalation exposure to dry fogging of H2O2 in a dental clinic. This cross-sectional, descriptive-analytical study was performed to determine the inhalation exposure and health risk of 9 dental clinic staff with H2O2 in six rooms. Occupational exposure to H2O2 was assessed using the OSHA VI-6 method and a personal pump with the flow rate of 500 mL/min connected to the midget fritted-glass impinger containing 15 mL of TiOSO4 collecting solution. The health effects of H2O2 exposure were assessed using a respiratory symptoms questionnaire. The health risk assessment of inhaled exposure to H2O2 was also performed using the method provided by the Singapore occupational health department. The mean respiratory exposure of clinic staff to H2O2 was ranged from 1.3 to 2.83 ppm for six rooms which was above the limits recommended by international organizations. Dyspnea (44.4%), cough (33.3%), and nasal burning (22.2%) were the most prevalent health problems. The results also showed a medium risk for endodontics and surgery, and lower risk for periodontics, restorative care, orthodontics, and prosthetics. The results of this study indicate that when using an automated hydrogen peroxide-vapor fogger, calculating the spraying time based on room volume and using the rooms after 30 min of fogging is very important and can greatly reduce the risk ranking.