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

Investigation of air dispersal during a rhinovirus outbreak in a pediatric intensive care unit

BACKGROUND

While airborne transmission of rhinovirus is recognized in indoor settings, its role in hospital transmission remains unclear.

METHODS

We investigated an outbreak of rhinovirus in a pediatric intensive care unit (PICU) to assess air dispersal. We collected clinical, environmental, and air samples, and staff's surgical masks for viral load and phylogenetic analysis. Hand hygiene compliance and the number of air changes per hour in the PICU were measured. A case-control analysis was performed to identify nosocomial rhinovirus risk factors.

RESULTS

Between March 31, 2023, and April 2, 2023, three patients acquired rhinovirus in a cubicle (air changes per hour: 14) of 12-bed PICU. A portable air-cleaning unit was placed promptly. Air samples (72,000 L in 6 hours) from the cohort area, and outer surfaces of staff's masks (n = 8), were rhinovirus RNA-negative. Hand hygiene compliance showed no significant differences (31/34, 91.2% vs 33/37, 89.2%, P = 1) before and during outbreak. Only 1 environmental sample (3.8%) was positive (1.86 × 103 copies/mL). Case-control and next-generation sequencing analysis implicated an infected staff member as the source.

CONCLUSIONS

Our findings suggest that air dispersal of rhinovirus was not documented in the well-ventilated PICU during the outbreak. Further research is needed to better understand the dynamics of rhinovirus transmission in health care settings.

COVID-19 in Workplace Settings: Lessons Learned for Occupational Medicine in the UK

This paper addresses lessons learned from the COVID-19 pandemic from a UK Occupational Medicine perspective to permit comparison with other national accounts. In spite of good prior research and statute, the necessary resources to protect workers' health were seriously lacking when the pandemic struck. Weak public health guidance, which did not recognise dominant airborne transmission, was applied to workplaces, leaving workers and others unprotected, especially in respect to Respiratory Protective Equipment (RPE). The Health and Safety Executive (HSE) as regulator was lacking, for example, in not producing guidance to protect HealthCare Workers (HCW) who were amongst the most at risk. The UK COVID-19 Public Inquiry should address shortcomings such as these, but recommendations must be accompanied by robust means to ensure appropriate implementation. These should range from substantial measures to improve indoor air quality, to a permanent pandemic management organization with adequate resources. The enforcing authority has to be obliged to publish more specific workplace guidance than the public health authorities. Occupational medicine as a discipline needs to be better prepared, and hence to assert its responsibility towards high standards of workers' health protection. Future research has to include investigating the best means of mitigation against airborne infection and the management of post-acute covid sequelae.

Indoor CO2 monitoring in a surgical intensive care unit under visitation restrictions during the COVID-19 pandemic

Background

Indoor CO₂ concentration is an important metric of indoor air quality (IAQ). The dynamic temporal pattern of CO₂ levels in intensive care units (ICUs), where healthcare providers experience high cognitive load and occupant numbers are frequently changing, has not been comprehensively characterized.

Objective

We attempted to describe the dynamic change in CO₂ levels in the ICU using an Internet of Things-based (IoT-based) monitoring system. Specifically, given that the COVID-19 pandemic makes hospital visitation restrictions necessary worldwide, this study aimed to appraise the impact of visitation restrictions on CO₂ levels in the ICU.

Methods

Since February 2020, an IoT-based intelligent indoor environment monitoring system has been implemented in a 24-bed university hospital ICU, which is symmetrically divided into areas A and B. One sensor was placed at the workstation of each area for continuous monitoring. The data of CO₂ and other pollutants (e.g., PM2.5) measured under standard and restricted visitation policies during the COVID-19 pandemic were retrieved for analysis. Additionally, the CO₂ levels were compared between workdays and non-working days and between areas A and B.

Results

The median CO₂ level (interquartile range [IQR]) was 616 (524-682) ppm, and only 979 (0.34%) data points obtained in area A during standard visitation were ≥ 1,000 ppm. The CO₂ concentrations were significantly lower during restricted visitation (median [IQR]: 576 [556-596] ppm) than during standard visitation (628 [602-663] ppm; p < 0.001). The PM2.5 concentrations were significantly lower during restricted visitation (median [IQR]: 1 [0-1] μg/m³) than during standard visitation (2 [1-3] μg/m³; p < 0.001). The daily CO₂ and PM2.5 levels were relatively low at night and elevated as the occupant number increased during clinical handover and visitation. The CO₂ concentrations were significantly higher in area A (median [IQR]: 681 [653-712] ppm) than in area B (524 [504-547] ppm; p < 0.001). The CO₂ concentrations were significantly lower on non-working days (median [IQR]: 606 [587-671] ppm) than on workdays (583 [573-600] ppm; p < 0.001).

Conclusion

Our study suggests that visitation restrictions during the COVID-19 pandemic may affect CO₂ levels in the ICU. Implantation of the IoT-based IAQ sensing network system may facilitate the monitoring of indoor CO₂ levels.