Risk Assessment of Hydrogen Peroxide Low- Temperature Plasma Sterilization Using Different Monitoring Methods

Objective:This study aims to evaluate the application value of biological monitoring and different types of chemical indicator cards in batch monitoring of hydrogen peroxide low-temperature plasma sterilization.The goal is to standardize the selection of loading conditions for this sterilization method and avoid positive biological monitoring results.Methods:Physical monitoring,Class I chemical indicator card monitoring,Class IV chemical indicator card monitoring,and biological monitoring were used to monitor the hydrogen peroxide low-temperature plasma sterilization process.The sterilization effect on instruments inside the Johnson&Johnson 100S plasma sterilizer was monitored and the qualification of various monitoring methods was compared.Results:The comparison showed that when non-standard or adsorption-prone packaging materials were used,the interception rate of biological monitoring and Class IV chemical indicator cards was significantly higher than that of physical monitoring and Class I chemical indicator cards.These methods more intuitively and effectively detected sterilization failures.Conclusion:Biological monitoring and Class IV chemical indicator cards are safe,fast,accurate,and easy to interpret in hydrogen peroxide low-temperature plasma sterilization,especially for monitoring instruments inside packages.They provide a reliable basis for the release of sterilized instrument packages.Identifying the reasons for positive biological monitoring results in hydrogen peroxide low-temperature plasma sterilization and taking effective measures promptly can minimize associated risks.

Evolutionary processes and sources of high-nitrate haze episodes over Beijing,Spring

Rare and consecutive high-nitrate haze pollution episodes were observed in Beijing in spring2012. We present detailed characterization of the sources and evolutionary mechanisms of this haze pollution, and focus on an episode that occurred between 15 and 26 April. Submicron aerosol species were found to be substantially elevated during haze episodes, and nitrates showed the largest increase and occupation（average： 32.2%） in non-refractory submicron particles（NR-PM1）, which did not occur in other seasons as previously reported. The haze episode（HE） was divided into three sub-episodes, HEa, HEb, and HEc. During HEa and HEc, a shallow boundary layer, stagnant meteorological conditions, and high humidity favored the formation of high-nitrate concentrations, which were mainly produced by three different processes —daytime photochemical production, gas-particle partitioning, and nighttime heterogeneous reactions — and the decline in visibility was mainly induced by NR-PM1.However, unlike HEa and HEc, during HEb, the contribution of high nitrates was partly from the transport of haze from the southeast of Beijing — the transport pathway was observed at ~800–1000 m by aerosol Lidar —and the decline in visibility during HEb was primarily caused by PM（2.5）. Our results provide useful information for air quality improvement strategies in Beijing during Spring.