Large-scale evaluation of microorganism inactivation by bipolar ionization and photocatalytic devices

COVID-19 Mitigation in a K-12 School Setting: A Case Study of Avenues: The World School in New York City

In this case study, we describe a well-resourced private school in New York City that implemented COVID-19 mitigation measures based on public health expert guidance and the lessons learned from this process. Avenues opened in New York City in 2012 and has since expanded, becoming Avenues: The World School, with campuses in São Paulo, Brazil; Shenzhen, China; the Silicon Valley, California; and online. It offers education at 16 grade levels: 2 early learning years, followed by a prekindergarten through grade 12. We describe the mitigation measures that Avenues implemented on its New York campus. We compare COVID-19 case prevalence at the school with COVID-19 case positivity in New York City, as reported by the New York State Department of Health. We also compare the school's indoor air quality to ambient indoor air quality measures reported in the literature. The school's mitigation measures successfully reduced the prevalence of COVID-19 among its students, staff, and faculty. The school also established a consistently high level of indoor air quality safety through various ventilation mechanisms, designed to reduce common indoor air pollutants. The school received positive parent and community feedback on the policies and procedures it established, with many parents commenting on the high level of trust and quality of communication established by the school. The successful reopening provides useful data for school closure and reopening standards to prepare for future pandemic and epidemic events.

Reducing Transmission of Airborne Respiratory Pathogens: A New Beginning as the COVID-19 Emergency Ends

BACKGROUND

In response to the COVID-19 pandemic, new evidence-based strategies have emerged for reducing transmission of respiratory infections through management of indoor air.

OBJECTIVES

This paper reviews critical advances that could reduce the burden of disease from inhaled pathogens and describes challenges in their implementation.

DISCUSSION

Proven strategies include assuring sufficient ventilation, air cleaning by filtration, and air disinfection by germicidal ultraviolet (UV) light. Layered intervention strategies are needed to maximize risk reduction. Case studies demonstrate how to implement these tools while also revealing barriers to implementation. Future needs include standards designed with infection resilience and equity in mind, buildings optimized for infection resilience among other drivers, new approaches and technologies to improve ventilation, scientific consensus on the amount of ventilation needed to achieve a desired level of risk, methods for evaluating new air-cleaning technologies, studies of their long-term health effects, workforce training on ventilation systems, easier access to federal funds, demonstration projects in schools, and communication with the public about the importance of indoor air quality and actions people can take to improve it. https://doi.org/10.1289/EHP13878.

Scoping review on the efficacy of filter and germicidal technologies for capture and inactivation of micro-organisms and viruses

The COVID-19 (SARS-CoV-2) pandemic increased the focus on preventing contamination with airborne pathogens (e.g. viruses, bacteria, and fungi) by reducing their concentration. Filtration, UV or ionization technologies could contribute to air purification of the indoor environment and inactivation of micro-organisms. The aim of this study was to identify the relevant literature and review the scientific evidence presented on the efficacy of filter and germicidal technologies (e.g. non-physical technologies) in air purification applications used to capture and inactivate micro-organisms and airborne viruses (e.g. SARS-CoV-2, rhinovirus, influenzavirus) in practice. A scoping review was performed to collect literature. Adopting exclusion criteria resulted in a final number of 75 studies to be included in this research. Discussion is presented on inactivation efficiencies of ultraviolet germicidal irradiation (UVGI) and ionization applications in laboratory studies and in practice. Specific attention is given to studies relating the use of UVGI and ionization to inactivation of the SARS-CoV-2 virus. Based on the consulted literature, no unambiguous conclusions can be drawn regarding the effectiveness of air purification technologies in practice. The documented and well-controlled laboratory studies do not adequately represent the practical situation in which the purifier systems are used.

Impact of test methodology on the efficacy of triethylene glycol (Grignard Pure) against bacteriophage MS2

The COVID-19 pandemic has raised interest in using chemical air treatments as part of a strategy to reduce the risk of disease transmission, but more information is needed to characterize their efficacy at scales translatable to applied settings and to develop standardized test methods for characterizing the performance of these products. Grignard Pure, a triethylene glycol (TEG) active ingredient air treatment, was evaluated using two different test protocols in a large bioaerosol test chamber and observed to inactivate bacteriophage MS2 in air (up to 99.9% at 90 min) and on surfaces (up to 99% at 90 min) at a concentration of approximately 1.2 - 1.5 mg/m3. Introducing bioaerosol into a TEG-charged chamber led to overall greater reductions compared to when TEG was introduced into a bioaerosol-charged chamber, although the differences in efficacy against airborne MS2 were only significant in the first 15 min. Time-matched control conditions (no TEG present) and replicate tests for each condition were essential for characterizing treatment efficacy. These findings suggest that chemical air treatments could be effective in reducing the air and surface concentrations of infectious pathogens in occupied spaces, although standard methods are needed for evaluating their efficacy and comparing results across studies. The potential health impacts of chronic exposure to chemicals should also be considered, but those were not evaluated here.

Effectiveness of a combined UV-C and ozone treatment in reducing healthcare-associated infections in hospital facilities

BACKGROUND

Hospital-acquired infections pose an ongoing threat to patient safety due to the presence of multi-drug-resistant organisms (MDROs) and other pathogens such as Clostridioides difficile which are dependent on thorough and effective cleaning and disinfection by personnel.

METHODS

This study evaluated the influence of UV-C air treatment: the air in the room was sanitized by UV-C and redirected into the room. In addition, ozone was released into the room to treat actual surfaces in low-risk areas such as hospital gyms, and high- to medium-risk areas such as hospital rooms. To this aim, a portable device designed for treating the environment air was tested against nine bacterial strains including Aspergillus spp. and Clostridioides spp.

RESULTS

The use of UV-C air treatment during daily operations and ozone treatment achieved at least a 2-log10 pathogen reduction except for Clostridioides spp.

CONCLUSION

Effective prevention of C. difficile normally requires the use of combined approaches that include chemical compounds and disinfection agents whose toxicity can be harmful not only to patients but also to healthcare personnel. Thus, the proposed no-touch device may be evaluated in future research to assess the needed requirements for its possible and full implementation in hospitals.

Efficient deactivation of aerosolized pathogens using a dielectric barrier discharge based cold-plasma detergent in environment device for good indoor air quality

Air pollution is one of the top 5 risks causing chronic diseases according to WHO and airborne transmitted pathogens infection is a huge challenge in the current era. Long living pathogens and small size aerosols are not effectively dealt with by the available indoor air purifiers. In this work, a dielectric barrier discharge (DBD) based portable cold-plasma detergent in environment device is reported and its disinfection efficiency has been analyzed in the indoor environment of sizes up to 3 × 2.4 × 2.4 m³. The deactivation efficiency of total microbial counts (TMCs) and total fungal counts (TFCs) is found to be more than 99% in 90 min of continuous operation of the device at the optimized parameters. The complete inactivation of MS2 phage and Escherichia coli bacteria with more than 5 log reduction (99.999%) has also been achieved in 30 min and 90 min of operation of the device in an enclosed environment. The device is able to produce negative ions predominantly dominated by natural plasma detergent along with positive ions in the environment similar to mother nature. The device comprises a coaxial DBD geometry plasma source with a specially designed wire mesh electrode of mild steel with a thickness of 1 mm. The need for feed gas, pellets and/or differential pressure has been eliminated from the DBD discharge source for efficient air purification. The existence of negative ions for more than 25 s on average is the key advantage, which can also deactivate long living pathogens and small size aerosols.

Direct and indirect healthcare and carbon savings with ACTIVE Particle ControlTM air-purification

Controlling airborne transmitted disease remains a challenge to clinicians, healthcare administrators, and engineers. Engineering measures are critical to any infection control program but can require extensive installation procedures, may be expensive to maintain, and may not always demonstrate clinical or financial benefit. We determined the financial and carbon benefits of an engineering solution to combat air pollutants and to control airborne transmitted disease. We determined the costs of healthcare associated infections (HAIs), and the costs of installation, maintenance, energy demands, and carbon impacts of an ACTIVE Particle ControlTM (APC) air-purification system. In a 20 month study with over 65,000 patient days the significant reductions in HAIs resulted in significant financial, energy, maintenance, and carbon savings from this engineering solution. Positive clinical and financial outcomes are possible with novel air-purification solutions such as APC.