Evaluating transmission risk in unique workplaces: pilot study of a Victorian prison

by | Mar 30, 2022 | Blogs, Theme 2: Transmission modelling | 0 comments

As part of Theme 2 of PROTECT, researchers at the Universities of Cambridge and Strathclyde have been investigating ventilation in prisons and the impact this could have on transmission in these high-risk settings.  In this blog, Cristina Rodriguez Rivero and Sara Mohamed discuss the project.

Prisons are epicentres for infectious diseases due to the existing prevalence of infections, higher levels of infection risk factors, the unavoidability of close contact in often overcrowded, poorly ventilated, and unsanitary facilities, and poor healthcare access relative to the broader community. Contagions can be transmitted between prisoners, staff and visitors, between prisons through transfers and staff cross-deployment, and through contact with the wider community. Accordingly, prisons and other custodial settings represent an integral part of the public health response to COVID-19, as explosive outbreaks can overwhelm prison healthcare services and put additional demand on overburdened specialist facilities in the community.

Given prisoners live in close proximity under poor ventilation conditions, risk levels for transmission via inhaled respiratory particles are higher. Additionally, prisoners and staff generally have more comorbidities and are in worse overall health than the general population. Many scholars have appealed for the revision of prison guidelines regarding infection control on the grounds that most prisoners will eventually be released back into their community, where they can further spread infectious diseases. Although this is especially true for the COVID-19 context, despite the substantial media attention on screening in the UK, the burden of asymptomatic transmission and the extent of airborne transmission in closed settings remain uncertain.

In response to the need for revised guidelines, PROTECT researchers from the University of Strathclyde and the University of Cambridge are collaborating with the Ministry of Justice to assess how ventilation levels in prisons affect the spread of respiratory particles in the various areas of these complex spaces, and understand where and how ventilation monitoring can occur in prisons.

The work will ultimately be comprised of three phases and it focuses on both prison buildings of Victorian architecture style and new-builds (post-1992). The former type composes a third of the estate of HM Prison Services. They were built around the 1870s and 1880s, when ventilation understanding was poor and the implementation of effective ventilation methods was not considered in their design. Therefore, investigating how ventilation flows behave and how communal and individual spaces connect is vital to understanding associated risk of transmission and to inform policy on how to mitigate this risk.

We summarise here the tests carried out for the first phase, a pilot study, which has comprised collation of data for air quality and airflow distributions. The experimental work for this pilot study was done in the decommissioned prison of HMP Reading, where environmental and CO2 monitors were installed, and artificial smoke tracing tests were conducted. Environmental and CO2 measurements allow the collation and monitoring of various parameters defining the air quality, while the gas tracing tests allow the visualisation of the movement of air within the various tested spaces of the prison.

With the data obtained from these tests, the research group has estimated ventilation rates due to the contribution of different processes, such as leakage-, buoyancy- and wind-driven flows and has identified various sources of connectivity of spaces, and optimal locations for monitors, among other information. Further studies will be carried out in similar buildings in the following phases, which will also involve detailed longitudinal monitoring of CO2 and environmental conditions over two to three weeks to capture temporal, spatial and seasonal variations. The data will be collated and analysed to identify the importance of ventilation and environmental conditions on airborne pathways and transmission risk in prison settings.

No studies had yet investigated ventilation monitoring in a UK prison setting or in the COVID-19 context. As such, this study will provide novel insights into how environmental monitoring can be applied in such settings to reduce transmission of the COVID-19 virus. The research could also have implications for other academic areas, including epidemiology, public health management and criminology.

For more information, please contact the authors: mcr51@cam.ac.uk and/or sara.mohamed@strath.ac.uk.


Recent Comments

    Google Analytics Stats

    generated by GADWP