Observation of nanoaerosol release from a hand dryer

Consumer exposure is one of exposures in the life cycle perspective to risk assessment. Many nanoproducts have been commercialized in the fields of health, electronics, home, food etc. Hand dryers are widely used at public rest rooms. In this study, we selected the hand dryer having a filter coated with silver nanoparticles as a popular electronic nanoproduct. A test chamber system was developed to detect nanoaerosols released from the test nanoproduct during the operation. The particle number concentration of the chamber background was confirmed to be <1 particles/cm3 by using a condensation particle counter with a detection limit of 10 nm. When the hand dryer was turn on for 1 min, the particle number concentration in the chamber was almost linearly increased up to the peak concentration (<20 particles/cm3). It was slowly decreased after the hand dryer was turn off. When the operation was extended to 10 min, similar release pattern of nanoaerosols was observed. Therefore, it was concluded that the nanoaerosols was emitted from the hand dryer during the operation. However, the amount of released nanoaerosols was negligible, compared to indoor nanoaerosol concentration (∼10,000 particles/cm3). Also, the released nanoaerosols could not be analyzed by filter sampling due to small quantity of mass.