Detection of SARS-CoV-2 in high-efficiency particulate air (HEPA) filters of low-cost air purifiers in community-based organizations.

This study aims to investigate the presence of SARS-CoV-2 in public spaces and assess the utility of inexpensive air purifiers equipped with high-efficiency particulate air (HEPA) filters for viral detection. Samples were collected from six community-based organizations in underserved minority neighborhoods in Northwest Miami, Florida, from February to May 2022. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect SARS-CoV-2 in air purifier filters and surface swabs. Among 32 filters tested, three yielded positive results, while no positive surface swabs were found. Notably, positive samples were obtained exclusively from child daycare centers. These findings highlight the potential for airborne transmission of SARS-CoV-2 in indoor air, particularly in child daycare centers. Moreover, the study demonstrates the effectiveness of readily available HEPA filters in detecting the virus. Improving indoor ventilation and implementing air filtration systems are crucial in reducing COVID-19 transmission where people gather. Air filtration systems incorporating HEPA filters offer a valuable approach to virus detection and reducing transmission risks. Future research should explore the applicability of this technology for early identification and mitigation of viral outbreaks.

Laminar airflow ventilation systems in orthopaedic operating room do not prevent surgical site infections: a systematic review and meta-analysis.

BACKGROUND: Laminar airflow (LAF) technologies minimize infectious microorganisms to enhance air quality and surgical site infections (SSIs). LAF lowers SSIs in some clinical studies but not others. This study analyzes laminar airflow ventilation's capacity to reduce orthopaedic surgery-related SSIs. METHODS: The PRISMA-compliant keywords were utilized to conduct a search for pertinent articles in various databases including PubMed, MEDLINE, CENTRAL, Web of Sciences, and the Cochrane databases. Observational studies, including retrospective, prospective, and cohort designs, satisfy the PICOS criteria for research methodology. The assessment of quality was conducted utilizing the Robvis software, while the meta-analysis was performed using the RevMan application. The study's results were assessed based on effect sizes of odds ratio (OR) and risk ratio (RR). RESULTS: From 2000 to 2022, 10 randomized controlled clinical trials with 10,06,587 orthopaedic surgery patients met the inclusion criteria. The primary outcomes were: (1) Risk of SSI, (2) Bacterial count in sampled air and (3) Reduction in SSIs. The overall pooled OR of all included studies was 1.70 (95% CI 1.10-2.64), and the overall pooled RR was 1.27 (95% CI 1.02-1.59) with p < 0.05. LAF is ineffective at preventing SSIs in orthopaedic procedures due to its high-risk ratio and odds ratio. CONCLUSIONS: The present meta-analysis has determined that the implementation of LAF systems does not result in a significant reduction in the incidence of surgical site infections (SSIs), bacterial count in the air, or SSIs occurrence in orthopaedic operating rooms. Consequently, the installation of said equipment in operating rooms has been found to be both expensive and inefficient.

Impact of supplementary air filtration on aerosols and particulate matter in a UK hospital ward: a case study.

BACKGROUND: Aerosol spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a major problem in hospitals, leading to an increase in supplementary high-efficiency particulate air filtration aimed at reducing nosocomial transmission. This article reports a natural experiment that occurred when an air cleaning unit (ACU) on a medicine for older people ward was switched off accidentally while being commissioned. AIM: To assess aerosol transport within the ward and determine whether the ACU reduced airborne particulate matter (PM) levels. METHODS: An ACU was placed in a ward comprising two six-bedded bays plus three single-bed isolation rooms which had previously experienced several outbreaks of coronavirus disease 2019. During commissioning, real-time measurements of key indoor air quality parameters (PM1-10, CO2, temperature and humidity) were collected from multiple sensors over 2 days. During this period, the ACU was switched off accidentally for approximately 7 h, allowing the impact of the intervention on PM to be assessed. FINDINGS: The ACU reduced the PM counts considerably (e.g. PM1 65.5-78.2%) throughout the ward (P<0.001 all sizes), with positive correlation found for all PM fractions and CO2 (r=0.343-0.817; all P<0.001). PM counts rose/fell simultaneously when the ACU was off, with correlation of PM signals from multiple locations (e.g. r=0.343-0.868; all P<0.001) for particulates <1 µm). CONCLUSION: Aerosols migrated rapidly between the various ward subcompartments, suggesting that social distancing alone cannot prevent nosocomial transmission of SARS-CoV-2 as this fails to mitigate longer-range (>2 m) transmission. The ACU reduced PM levels considerably throughout the ward space, indicating its potential as an effective intervention to reduce the risk posed by infectious airborne particles.

Patterns and Predictors of Air Cleaner Adherence Among Adults with COPD.

Rational: Poor indoor air quality has been associated with worse chronic obstructive pulmonary disease (COPD) morbidity. In-home portable air cleaners reduce indoor pollutants and could improve respiratory health. Factors associated with air cleaner adherence among adults with COPD remains unknown. Methods: In a 6-month trial of former smokers with COPD, participants (n=116) received active or sham portable air cleaners. Air cleaner adherence was measured by electronic monitors. Potential baseline predictors of adherence included individual factors (demographics, socioeconomic status, smoking history, psychological well-being), COPD disease severity, and housing characteristics. Time and season were also considered. Stepwise logistic regression and longitudinal fixed effect analysis were performed to assess independent predictors of adherence. Results: A total of 109 participants had an objective measure of adherence, and 76.1% used at least 1 air cleaner 80% of the time (defined a priori as adherent). Higher annual household income ≥$35,000 (odds ratio [OR]=4.4, 95% confidence interval [CI], 1.1-18.0) and use of heat pump/electricity (versus gas) for heating (OR=6.1, 95%CI, 1.7-22.4) were associated with higher odds of adherence. Further, poor quality of life (St George's Respiratory Questionnaire, per 10-point increase) and prior year exacerbations were associated with lower odds of adherence (OR=0.65, 95%CI, 0.4-1.0) and (OR=0.26, 95%CI, 0.1-0.9), respectively. Adherence was highest during the first month and lower during winter compared to other seasons. Conclusion: These findings suggest that cold weather season, use of gas for home heating, and lower annual income negatively impact adherence. Poor quality of life and worse disease control may also decrease adherence. Addressing factors associated with air cleaner adherence should be considered when designing future environmental studies.

Climatization systems for Brazilian dental teaching clinics: a narrative review in the context of the COVID-19 pandemic / Sistemas de climatização das clínicas de ensino odontológico brasileiras: uma revisão narrativa no contexto da pandemia da COVID-19

COVID-19 outbreackhas reaffirmed the need to maintain ventilation of dental environments properly. This study was carried out to encourage a reflective analysis of the risks of air contamination in Brazilian dental clinics. A narrative review of the literature was carried out on the recommendations of heating, ventilation and air conditioning (HVAC) systems in dental environments, considering the risks of air contamination in Brazilian dental teaching clinics. The literature research was conductedin the PubMedand Google Scholar databases and the main studiesthat evaluated the climatization systems and portable high efficiency particulate air filtration (HEPA)units in dental environments were included. Furthermore, it were analyzed the guidelines of the Centers for Disease Control and Prevention, the Brazilian National Health Surveillance Agency, the Brazilian Ministry of Health and important institutions of the different countries. After the initial research, a review of the guidelines and articles that assess the use of HEPA units to improve air cleanliness. This analysis was done by different groups of researchers. All documents mentioned that the air quality of the dental offices must follow the protocols in current legislation to ensure the safety of the environs. Theyreaffirmed that the COVID-19 pandemic makes it imperative that dental environments equipped with air conditioning have mechanical air renewal devices. An alternative for Brazilian dental teaching clinics equipped with mini-splits or window air conditioning could be the installation of exhaust fans and portable HEPA filter units to exchange air and reduce aerosols inside the environments (AU).

O surto de COVID-19 reafirmou a necessidade de manter adequadamente a ventilação dos ambientes odontológicos. Este estudo foi realizado para incentivar uma análise reflexiva sobre os riscos de contaminação do ar em clínicas de odontologia. Foi realizada uma revisão narrativa da literatura sobre as recomendações dos sistemas de aquecimento,ventilação e ar-condicionado (AVAC) em ambientes odontológicos, considerando os riscos de contaminação do ar nas clínicas de ensino odontológico brasileiras. A pesquisa bibliográfica foi realizada nas bases de dados PubMed e Google Acadêmico e foram incluídos os principais estudos que avaliaram os sistemas de climatização e unidades portáteis com filtragem de partículas de alta eficiência(HEPA)em ambientes odontológicos. Além disso, foram analisadas as diretrizes do Centro de Controle e Prevenção de Doenças, da Agência Nacional de Vigilância Sanitária, do Ministério da Saúde e de importantes instituições de diferentes países. Após a pesquisa inicial, foi realizada uma revisão das diretrizes e dos artigos que avaliaram o uso de unidades HEPA para melhorar a limpeza do ar. Essa análise foi feita por diferentes grupos de pesquisadores. Todos os documentos mencionaram que a qualidade do ar dos consultórios odontológicos deve seguir os protocolos da legislação vigente para garantir a segurança dos ambientes. Eles reafirmam que a pandemia da COVID-19 torna imprescindível que os ambientes odontológicos, equipados com ar-condicionado, tenham dispositivos mecânicos de renovação de ar. Uma alternativa para as clínicas de ensino odontológicas brasileiras equipadas comminisplitsou ar-condicionado de janela poderia ser a instalação de exaustores e unidades portáteis de filtro HEPA para fazer as trocas de ar e reduzir os aerossóis no interior dos ambientes (AU).

The effect of a mobile HEPA filter system on 'infectious' aerosols, sound and air velocity in the SenseLab.

High efficiency air filtration has been suggested to reduce airborne transmission of 'infectious' aerosols. In this study the 'air cleaning' effect as well as the effect on sound and air velocity (draught risk) of a mobile High-Efficiency Particulate Air (HEPA) filter system was tested for different settings and positions in the Experience room of the SenseLab. From both the noise assessments by a panel of subjects and sound monitoring it was concluded that the mobile HEPA filter system causes an unacceptable background sound level in the tested classroom setting (Experience room). With respect to the air velocity measurements and draught rating calculations, it was concluded that both depend on the position and the setting of the HEPA filter system as well as on the position and height of the measurements. For the removal of aerosols simulated by air-filled soap bubbles in front of the subject, the mobile HEPA filter system performed better as compared to the 'No ventilation' regime, for all settings and both positions, and for some settings, even better than all the tested mixing ventilation regimes. The use of a mobile HEPA filter system seems a good additional measure when only natural ventilation options are available. Future research should focus on rooms of different sizes or shapes, as this may also play a role in the filter's performance, noise and draught effects.

Air bio-contamination control in hospital environment by UV-C rays and HEPA filters in HVAC systems.

The contamination of air-handling units is a widespread phenomenon in buildings with air-conditioning systems, including hospitals. The germicide capacity of UV-C rays is known and, in the air-conditioning apparatuses, the UV-C lamps are generally located inside the air ducts. Aim of the paper is to evaluate the effectiveness of UV-C lamps when they are differently placed, i.e. in a position to directly irradiate the HEPA filters surface. We built ad hoc experimental air-conditioning systems, with HEPA filters and UV-C lamps in the two described positions. The results obtained demonstrate that, for disinfection purpose, the direct irradiation of the HEPA filters by UV-C provides better results than irradiation of the air stream and the effectiveness increases when lowering the relative humidity of the air. The survival curves of the tested microorganisms (fungi) show typical tail shaped curves (two steps survival curves). Additional tests using both HEPA filters alone, and HEPA filters plus UV lamps, have been performed measuring the air pressure drop between entrance and exit the HEPA filters and collecting air samples in order to obtain total microbial and fungal count. The results obtained suggest that, at least in experimental conditions described, the radiation on filter surface reduces significantly the microbial load and the pressure drop through the filter, compared to a situation of not-irradiated HEPA filters.

Fungal aerocontamination exposure risk for patients in 3 successive locations of a pediatric hematology unit department: Influence of air equipment and building structure on air quality.

BACKGROUND: Invasive fungal infections (IFIs) play an important role in the mortality of immunocompromised patients. The pediatric hematology department (PHD) at Besançon University Hospital has relocated 3 times: (1) from a building without an air filtration system (B1), (2) to a renovated building with low air pressure (B2), and (3) to a new building with high air pressure and high-efficiency particulate air filters (B3). This study aimed to investigate how these relocations influenced the fungal exposure risk for the PHD's patients. METHODS: Air samples were taken monthly in patient rooms and weekly in corridors. The detection of opportunistic fungi species was used to assess IFI risk. Data were analyzed using univariate and multivariate random-effects negative binomial regression. RESULTS: A total of 1,074 samples from 29 rooms over a 10-year period showed that renovation of an old building with a basic ventilation system did not lead to a significant improvement of air quality (P = .004, multivariate analysis). Among factors linked to higher risk of patient rooms mold contamination was fungal contamination of the corridors (P <.001). CONCLUSIONS: This study demonstrates that corridors can be used as reliable sentinel to prevent fungal contamination in patient rooms. Only relocation in building B3, equipped with laminar air flow, achieved adequate air quality.

Mobile ultra-clean unidirectional airflow screen reduces air contamination in a simulated setting for intra-vitreal injection.

The aim of this study is to determine whether the use of a mobile ultra-clean laminar airflow screen reduces the air-borne particle counts in the setting of a simulated procedure of an intra-vitreal injection. A mobile ultra-clean unidirectional airflow (UDF) screen was tested in a simulated procedure for intra-vitreal injections in a treatment room without mechanical ventilation. One UDF was passed over the instrument tray and the surgical area. The concentration of particles was measured in the background, over the instrument table, and next to the ocular area. The degree of protection was calculated at the instrument table and at the surgical site. Use of the UDF mobile screen reduced the mean particle concentration (particles > 0.3 microns) on the instrument table by a factor of at least 100.000 (p < 0.05), and over the patient's eye by at least a factor of 436 (p < 0.05), which in clinical practice translates into significantly reduced air contamination. Mobile UDF screen reduces the mean particle concentration substantially. The mobile UDF screen may therefore allow for a safer procedural environment for ambulatory care procedures such as intra-vitreal injections in treatment rooms.

Portable air cleaners should be at the forefront of the public health response to landscape fire smoke.

Landscape fires can produce large quantities of smoke that degrade air quality in both remote and urban communities. Smoke from these fires is a complex mixture of fine particulate matter and gases, exposure to which is associated with increased respiratory and cardiovascular morbidity and mortality. The public health response to short-lived smoke events typically advises people to remain indoors with windows and doors closed, but does not emphasize the use of portable air cleaners (PAC) to create private or public clean air shelters. High efficiency particulate air filters and electrostatic precipitators can lower indoor concentrations of fine particulate matter and improve respiratory and cardiovascular outcomes. We argue that PACs should be at the forefront of the public health response to landscape fire smoke events.

Assessment of the risk of infectious aerosols leaking to the environment from BSL-3 laboratory HEPA air filtration systems using model bacterial aerosols.

To assess the risk of infectious bacterial aerosols leaking to the environment, the filtration efficiency of a biosafety level 3 (BSL-3) laboratory high-efficiency particulate (HEPA) filter was investigated using the aerosolized bacteria Serratia marcescens. The aerosol size was measured using an Andersen sampler. Eight first stage HEPA filters (numbered 1-8) were distributed in contaminated labs and exhausts from each of the first stage HEPA filters were aggregated and filtered through one second stage HEPA filter before being released to the environment. In total, 8 first-stage and 1 second-stage HEPA filters from the BSL-3 air purification system were analyzed. No S. marcescens was detected in first stage filters 1, 2, 4, 5, 7 and 8 and the second stage HEPA filter. The filtration efficiencies against aerosolized S. marcescens were >99.9999%. First stage filter numbers 3 and 6 had filtration efficiencies of 99.9825% and 99.9906%, respectively. When filter number 3 was replaced by a new filter and the bracket for filter number 6 was sealed, no aerosolized S. marcescens was detected in the filtered air. Our work suggests that the BSL-3 laboratory HEPA filter air purification system is effective against bacterial aerosols, with little to no bacterial leakage into the environment.

Fungal pollution of indoor environments and its management.

Indoor environments play important roles in human health. The health hazards posed by polluted indoor environments include allergy, infections and toxicity. Life style changes have resulted in a shift from open air environments to air tight, energy efficient, environments, in which people spend a substantial portion of their time. Most indoor air pollution comes from the hazardous non biological agents and biological agents. Fungi are ubiquitous in distribution and are a serious threat to public health in indoor environments. In this communication, we have reviewed the current status on biotic indoor air pollution, role of fungi as biological contaminants and their impact on human health.