Oh radical reduction and cell protection in the air by atomic hydrogen generated from atmospheric pressure plasma device

Summary form only given. Recently the presence of free radicals, in particular OH in indoor environments has received an increasing concern. It was reported that the OH radical initiates a complex series of reactions that generate still other radicals and ultimately produce species that can adversely affect human health in indoor environments. We have developed novel atmospheric pressure plasma device that generates atomic hydrogen to neutralize OH radical in indoor air. Device structure and formation of atomic hydrogen in the device have been reported in our previous paper. The purpose of this paper is to report the observation of OH radical reduction with the operation of this device by using spectroscopic and biological methods. Cell protection effects of the device from OH radicals in the air are reported. In the spectroscopic experiments, OH radicals were produced in the air by a dielectric barrier discharge. The laser-induced fluorescence (LIF) spectroscopy was employed for monitoring of the OH radical concentration. When the device was operated the OH-LIF intensity was remarkably reduced. In the biological experiments, we compared the cell death rate between cells exposed to reactive oxygen species with or without the device in operation. The operation of the device reduced the cell death caused by the OH radicals produced in the air by dielectric barrier discharge as well as the death induced by hydrogen peroxide produced enzymatically in the culture medium