Transmission of infectious agents via aerosols is an ever-present concern in animal agriculture production settings, as the aerosol route to disease transmission can lead to difficult-to-control and costly diseases, such as porcine respiratory and reproductive syndrome virus and influenza A virus. It is increasingly necessary to implement control technologies to mitigate aerosol-based disease transmission. Here, we review currently utilized and prospective future aerosol control technologies to collect and potentially inactivate pathogens in aerosols, with an emphasis on technologies that can be incorporated into mechanically driven (forced air) ventilation systems to prevent aerosol-based disease spread from facility to facility. Broadly, we find that control technologies can be grouped into three categories: (1) currently implemented technologies; (2) scaled technologies used in industrial and medical settings; and (3) emerging technologies. Category (1) solely consists of fibrous filter media, which have been demonstrated to reduce the spread of PRRSV between swine production facilities. We review the mechanisms by which filters function and are rated (minimum efficiency reporting values). Category (2) consists of electrostatic precipitators (ESPs), used industrially to collect aerosol particles in higher flow rate systems, and ultraviolet C (UV-C) systems, used in medical settings to inactivate pathogens. Finally, category (3) consists of a variety of technologies, including ionization-based systems, microwaves, and those generating reactive oxygen species, often with the goal of pathogen inactivation in aerosols. As such technologies are typically first tested through varied means at the laboratory scale, we additionally review control technology testing techniques at various stages of development, from laboratory studies to field demonstration, and in doing so, suggest uniform testing and report standards are needed. Testing standards should consider the cost-benefit of implementing the technologies applicable to the livestock species of interest. Finally, we examine economic models for implementing aerosol control technologies, defining the collected infectious particles per unit energy demand.

Airborne pathogens not only lead to epidemics and pandemics, but are associated with morbidity and mortality. Administrative or managerial control, environmental control and use of personal protective equipments are the three components in airborne infection control. National and international guidelines for ideal airborne infection control (AIC) practices are available for more than a decade; however the implementation of these need to be looked into, challenges identified and addressed for effective prevention of airborne disease transmission. Commitment of multiple stakeholders from policy makers to patients, budget allocation and adequate fund flow, functioning AIC committees at multiple levels with an inbuilt reporting and monitoring mechanism, adaptation of the AIC practices at various health care levels, supportive supervision, training and ongoing education for health care providers, behaviour change communication to patients to adapt the practices at health care facility level, by health care personnel and patients will facilitate health system preparedness for handling any emergencies, but will also help in reducing the burden of persisting airborne diseases such as tuberculosis. Operational research in this least focused area will also help to identify and address the challenges.

Airborne infection control (AIC) is a less focused aspect of tuberculosis (TB) prevention. We describe AIC practices in primary health care centres, awareness and practices of AIC among health care providers (HCPs) and TB patients. We implemented a package of interventions to improve awareness and practices among them and assessed its impact.
The study used a quasi-experimental study design. A semi-structured checklist was used for health facility assessment and a self-administered questionnaire of HCPs. Pre- and postintervention assessments were made in urban primary health centers (UPHCs), HCPs, and patients. Interventions included sharing facility-specific recommendations, AIC plans and guidelines, HCP training, and patient education. Statistical difference between the two time periods was assessed using the Chi-square test.
A total of 23 and 25 UPHCs were included for pre- and postintervention assessments. All 25 centers participated in interventions. Open areas were >20% of ground area in all facilities. No AIC committee was present in any of the facilities at both pre- and postintervention. Of all HCPs, 7% (23/337) versus 65% (202/310) had undergone AIC training. Good awareness improved from 24% (81/337) to 71% (220/310) after intervention (P < 0.001). Appropriate cough hygiene was known to 20% (51/262) versus 58% (152/263) patients at two assessments (P < 0.001).
Comprehensive intervention, including supportive supervision of health centers, training of HCPs, and patient education, can improve AIC practices.

Introduction The indoor air in hospitals could play a significant role in the transmission of a wide array of infections, especially in respiratory intensive care units, pulmonary outpatient departments, and other areas. Unprotected coughing and sneezing may facilitate the release of aerosols and contaminate the indoor environment. The majority of infections transmitted through these modes include viral diseases, including tuberculosis (TB), influenza, and measles, among several others. Moreover, the possibility of direct and indirect transmission of microbes by air has been underestimated in hospital settings, especially in developing countries. This study therefore was carried out to assess the burden of microbes in the air of selected wards in a tertiary care hospital and evaluate the occupational risk of some infections among healthcare workers (HCWs). Methods This study was carried out between September 2019 and February 2021 at a tertiary care teaching hospital in South India. A total of 30 symptomatic healthcare workers (HCWs) were included in the study and were screened for present and past tuberculosis (TB) as well as other lower respiratory tract infections. A tuberculin skin test, chest X-ray, and sputum acid-fast staining were performed on all the HCWs who were negative for other bacterial infections and were symptomatic. The study was conducted in coordination with the pulmonology department. Active monitoring of air was performed by microbiological air sampler in the respiratory intensive care unit (RICU) and other high-risk areas including the pulmonology outpatient department (OPD), the radiology OPD, and the microbiology department.  Results Sputum for tuberculous bacteria was positive in four (16.6%) HCWs. The chest X-ray showed radiological findings suggestive of TB in five (20.8%) HCWs. Three (12.5%) HCWs who were screened for extrapulmonary TB revealed one (33.3%) was positive for TB of the hip joint. Among the HCWs, eight (33%) returned positive tuberculin tests. Assessment of the hospital air in the RICU revealed the bacterial count (288 CFU/m3) exceeded the normal limit (≤50 CFU/m3). The COVID-19 isolation ward showed the lowest bacterial count (06 CFU/m3) and no fungi. The predominant bacterial isolates were gram-positive cocci in clusters (Methicillin-sensitive Staphylococcus aureus). After proper disinfection and correction of ventilation techniques, the resampling results noted microbial colonies under normal limits. Conclusion A high burden of TB was noted among the HCWs. The airborne infection control strategies are essential to minimize the risk of nosocomial infections and occupational TB risk to HCWs. Most microbes are transmitted through the airborne route and therefore it is extremely important to take measures to control the transmission of such pathogens in hospital settings.

Hospitalized persons with suspected pulmonary tuberculosis (PTB) are placed in airborne isolation to prevent nosocomial infection, as recommended by the Centers for Disease Control and Prevention (CDC). There is significant evidence that clinicians overuse this resource due to an abundance of caution when confronted with a patient with possible PTB. Many researchers have developed predictive tools based on clinical and radiographic data to assist clinicians in deciding which patients to place in respiratory isolation. We assessed the isolation practices for an urban hospital serving a large immigrant population and then retrospectively applied seven previously derived prediction models of isolation of PTB to our population. Our current clinical practice results in 76% of patients with PTB being placed in isolation on admission. However, 208 patients without PTB were placed in isolation unnecessarily for a total of 584 days. Four models had sensitivities greater than 90%, and two models had sensitivities of 100%. The use of these models would have potentially saved more than 150 days of patient isolation per year.

In emergencies like the COVID-19 pandemic, the reuse or reprocessing of filtering facepiece respirators (FFRs) may be required to mitigate exposure risk. Research gap: Only a few studies evaluated decontamination effectiveness against SARS-CoV-2 that are practical for low-resource settings. This study aimed to determine the effectiveness of a relatively inexpensive ultraviolet germicidal irradiation chamber to decontaminate FFRs contaminated with SARS-CoV-2. A custom-designed UVGI chamber was constructed to determine the ability to decontaminate seven FFR models including N95s, KN95, and FFP2s inoculated with SARS-CoV-2. Vflex was excluded due to design folds/pleats and UVGI shadowing inside the chamber. Structural and functional integrity tolerated by each FFR model on repeated decontamination cycles was assessed. Twenty-seven participants were fit-tested over 30 cycles for each model and passed if the fit factor was ≥100. Of the FFR models included for testing, only the KN95 model failed filtration. The 3M™ 3M 1860 and Halyard™ duckbill 46727 (formerly Kimberly Clark) models performed better on fit testing than other models for both pre-and-post decontaminations. Fewer participants (0.3 and 0.7%, respectively) passed fit testing for Makrite 9500 N95 and Greenline 5200 FFP2 and only two for the KN95 model post decontamination. Fit testing appeared to be more affected by donning & doffing, as some passed with adjustment and repeat fit testing. A ≥ 3 log reduction of SARS-CoV-2 was achieved for worn-in FFRs namely Greenline 5200 FFP2. Conclusion: The study showed that not all FFRs tested could withstand 30 cycles of UVGI decontamination without diminishing filtration efficiency or facial fit. In addition, SARS-CoV-2 log reduction varied across the FFRs, implying that the decontamination efficacy largely depends on the decontamination protocol and selection of FFRs. We demonstrated the effectiveness of a low-cost and scalable decontamination method for SARS-CoV-2 and the effect on fit testing using people instead of manikins. It is recognized that extensive experimental evidence for the reuse of decontaminated FFRs is lacking, and thus this study would be relevant and of interest in crisis-capacity settings, particularly in low-resource facilities.

Introduction Postoperative infections represent a substantial burden to patients and healthcare systems. To improve patient care and reduce healthcare expenditures, interventions to reduce surgical infections must be employed. The crystalline C-band ultraviolet (UV-C) air filtration technology (Aerobiotix Inc., Miamisburg, OH, USA) has been designed to reduce airborne bioburden through high-quality filtration and germicidal irradiation. The purpose of this study was to assess the ability of a novel UV-C air filtration device to reduce airborne particle counts and contamination of surgical instrument trays in an operating room (OR) setting. Materials and methods Thirty sterile instrument trays were opened in a positive-air-flow OR. The trays were randomly assigned to one of two groups (UV-C or control, n=15 per group). In the UV-C group, the UV-C filtration device was used and in the control, it was not. All trays were opened with the use of a sterile technique and left exposed in the OR for four hours. Air was sampled by a particle counter to measure the numbers of 5µm and 10µm particles. Culture specimens were obtained from the trays to assess for bacterial contamination. Outcome data were collected at 30-minute intervals for the duration of the four-hour study period. Results Use of the UV-C device resulted in statistically significant reductions in the numbers of 5µm (average of 64.9% reduction when compared with the control, p<0.001) and 10µm (average of 65.7% reduction when compared with the control, p<0.001)-sized particles detectable in the OR. There was no significant difference in the overall rates of contamination (33.3% in the control group vs. 26.7% in the UV-C group, p=1.0) or the time to contamination (mean survival of 114 minutes in the control group vs. 105 minutes in the UV-C group, p=0.72) of surgical instrument trays with the use of the UV-C device. Conclusions The results demonstrate that the UV-C filtration device can successfully reduce airborne bioburden in standard ORs, suggesting that it may have the potential to reduce the risk for wound and hardware infections. Further clinical trials are necessary to better determine the effect of this air filtration system on postoperative infection rates.

BACKGROUND: Dilution ventilation by enhancing fresh air intake has been prescribed to reduce airborne infection spread during the COVID-19 pandemic. This is all the more important in assembly spaces like auditoriums. Premier technology institutes have large campuses with large auditoriums for academic and cultural events in India. These institutes serve as role models for society, where gatherings are essential, but there is also the possibility of transmission of all airborne respiratory infections, including tuberculosis, into the community. The fresh air taken in should also be filtered for pollution to prevent other lung issues.
OBJECTIVE: Fresh air intake and filtration have been studied in order to understand whether the outside air supplied indoors is filtered for PM2.5, which is a major ambient polluter in India. Settings and design/methods: In this study, the Right to Information Act of 2005 has been used to obtain first-hand information from the institutes with respect to the heating, ventilation, and air conditioning (HVAC) systems in their auditoriums. Twelve of the 19 institutes fall in cities with non-attainment of ambient air quality standards.
RESULTS: Eleven out of all those had recently integrated fresh air supply, and six replied in the negative. Only one out of all of them had appropriate filters.
CONCLUSIONS: This study highlights the need for a possible trade-off between the use of air conditioners for thermal comfort + assumed protection against PM2.5, which is the switching off of air conditioners and manually opening up windows and using fans for ventilation. Indian HVAC design for gathering spaces, especially educational institutes, needs to factor in fresh air for dilution ventilation as well as PM2.5 filtration.

Background Airports are hubs of diverse human interactions. During pandemics, they may serve as centers for the spread of airborne infection. Appropriate methods for the prevention of the spread of airborne infections must be integrated into the air conditioning systems of airports. Along with ultraviolet germicidal irradiation and other sanitization methods, dilution ventilation can be the easiest and most available method for the prevention of airborne infection, which means the intake of outside air into the indoors, which flushes out the aerosolized droplets containing pathogens. Though this process has been adopted by multiple buildings in reaction to the pandemic, it may present the challenge of intake of high concentration of suspended particulate matter in the intake air, a major air pollutant in developing countries, which may enter through the air conditioning systems. Appropriate filtration is necessary so that along with dilution ventilation for airborne disease prevention, the risk of suspended particulate matter of diameter 2.5 micron or PM2.5 induced lung issues is also reduced. Methodology The Right to Information Act, 2005, was used to file applications for information on the details of the air conditioning systems in Indian airports. The 58 airports in the study were also listed according to the list of cities that fall under the criteria for non-attainment of good air quality standards. Results Out of 58 airports considered, 27 fell in the \'non-attainment\' of good air quality list. On appraisal of filter systems, it was found that 23 had an intake of fresh air but only five had filters with a minimum efficiency reporting value (MERV) of 10 and above in their air conditioning systems, as is recommended for filtration of suspended particulate matter. Conclusion It can be concluded that most airports did not have the appropriate filter required for filtering PM2.5, which is a major pollutant in Indian cities. In light of coronavirus disease 2019, where dilution ventilation through the intake of outdoor air is suggested, it may also lead to the entry of air with high particulate matter into the indoors.

Background Hospital waiting areas are overlooked from the airborne infection control viewpoint as they are not classified as critical for infection control. This is the area where undiagnosed and potentially infected patients gather with susceptible and vulnerable patients, and there is no mechanism to segregate the two, especially when the potentially infected visitors/patients themselves are unaware of the infection or may be asymptomatic. It is important to know whether hospitals in Delhi, a populated, low-resource setting having community transmission/occurrence of airborne diseases such as tuberculosis, consider waiting areas as critical. Hence, this study aims to determine whether hospitals in Delhi consider waiting areas as critical areas from the airborne infection control viewpoint. Methodology The Right to Information Act, 2005, was used to request information from 11 hospitals included in this study. Results After compiling the results, it was found that five out of the 11 hospitals did not consider waiting areas as critical from the infection spread point of view. Two of the 11 hospitals acknowledged the criticality of waiting areas but did not include the same in the list of critical areas. Only three out of the 11 considered waiting areas as critical and included these in the list of critical areas in a hospital. Conclusions This study provided evidence that most hospitals in Delhi do not include waiting areas in the list of critical areas in a hospital.