Filtration efficiency of N95 filtering facepiece respirators during multi-cycles of '8-hour simulated donning + disinfection'.

BACKGROUND: Aerosol-borne diseases such as COVID-19 may outbreak occasionally in various regions of the world, inevitably resulting in short-term shortage and corresponding reuse of disposable respirators. AIM: To investigate the effective disinfection methods, reusable duration and frequency of N95 respirators. METHODS: Based on the self-built respirator simulation test system, and under combinations of experimental conditions of three N95 respirators × 0-200 nm NaCl aerosols × three simulated breathing flow rates (15, 50 and 85 L/min) × two disinfection methods (dry heating and ultraviolet (UV) radiation), this study continuously measured the changes in filtration efficiency of all respirators during multi-cycles of '8-h simulated donning + disinfection' until the penetration reached ≥5%. FINDINGS: Multi-cycles of dry heating and UV radiation treatments on the reused (i.e., multiple 8-h donning) N95 respirators had a minimal effect (<0.5%) on the respirator filtration efficiency, and even at 85 L/min, all tested N95 respirators were able to maintain filtration efficiencies ≥95% for at least 30 h or four reuse cycles of '8-h donning + disinfection', while a lower breathing flow rate (15 L/min) plus the exhalation valve could further extend the N95 respirator's usability duration up to 140 h or 18 reuse cycles of '8-h donning + disinfection'. As the respirator wearing time extended, aerosol penetration slowly increased in a quadratic function with a negative second-order coefficient, and the penetration increment during each cycle of 8-h donning was less than 0.9%. CONCLUSION: Multi-cycles of N95 respirator reuse in combination with dry heating or UV irradiation disinfection are feasible.

Product Service System Design of Agricultural Products based on Distributed System

The impact on public emergencies such as COVID-19 has created a greater disconnect from producers and consumers, which has also put pressure on economic growth. Distributed systems can create sustainable development by connecting individual production units and sharing resources between them. Based on the investigation of agricultural products of Qihe County, the distributed system theory and product service system design method are applied to analyze the needs of consumers, producers and their stakeholders of local agricultural products. With the help of small-scale interconnected regional production units, a distributed subsystem based on the characteristics of its own agricultural products is established. Through the design of agricultural products brands, traceable agricultural products safety system and agricultural products online sales APP, the production and sales forms can be flexibly adjusted to increase online purchasing and offline experience forms. Finally, it solves the pain points of users, adds local cultural elements, improves the added value of agricultural products, enhances the income of farmers, improves the quality of life of urban residents, and promotes the sustainable development of economy, society and environment. © 2021 IEEE.

APHC: Auditable and Privacy Preserving Health QR Code Based on Blockchain

The outbreak of COVID-19 has brought great pain to people around the world. As the epidemic continuing, prevention and control measures become particularly important. Then, the health QR code has been designed to tracing and controlling the epidemic. Through the health code, the confirmed cases and close contacts will be traced quickly. However, the health code records a great deal of residents’ privacy information and if it is leaked, the consequences will be severe. Although some existing health code schemes preserve the privacy, but most of them either do not support fine-grained auditability or are centralized health code storage. Therefore, we propose an auditable and privacy-preserving health QR code scheme based on blockchain. © 2022, Springer Nature Switzerland AG.

Influence of conducive weather on ozone in the presence of reduced NOx emissions: A case study in Chicago during the 2020 lockdowns

This study analyzes the response of near-surface O3 in Chicago to the COVID-19 lockdowns using observational data at the surface and from satellite. Even though the lockdowns caused NOx emissions to decrease by 18%, Chicago still experienced 17 high-O3 (>70 ppb) days in 2020, and the mean O3 mixing ratio did not show a significant change in 2020 compared with 2015–2019. Ozone production in summer 2020 in Chicago was in the “transitional” regime (HCHO/NO2 column ratio = 2.9), and not sensitive to changes in NOx in either direction. The primary driver for Chicago's O3 exceedances in 2020 was the dry tropical (DT) weather, which was associated with hot, dry, and stagnant meteorological conditions. There were 15 DT days in 2020, which led to more efficient production and greater accumulation of O3. The results suggest that a dramatic one-year 18% NOx reduction can be overcome by conducive meteorology and that NOx and VOC controls need to be more substantial and wide-ranging. This study also highlights the important role of different climate regimes, and not solely temperature, on the formation of O3. © 2022 Turkish National Committee for Air Pollution Research and Control