Guidance

AIRBODS WP3 Field Studies - Work Statement 

Updated 8 September 2021

Dr Liora Malki-Epshtein (WP Lead), UCL

Prof Malcolm Cook, (PI, AIRBODS consortium), Loughborough University

This document has been written following consultation with the AIRBODS research team. 

Proposed programme of work

Objectives

Our primary objective is to examine the risk of airborne transmission indoors, based on environmental data.  We aim to evaluate the risk by investigating how venues operate in practice in terms of ventilation and crowd management, to assess potential sources or scenarios leading to increased exposure to airborne infectious diseases (including, but not limited to Covid-19) and the relative risk of infection associated with this exposure. Finally, we aim to propose mitigation measures to reduce the risk of transmission at events due to factors related to the venue layout and factors related to the event organisation.

The team agrees that indoor venues, or indoor spaces integrated into outdoor venues, are those where there is a higher risk of “airborne” (via aerosols) transmission and exposure due to poor ventilation and accumulation of the virus in exhaled breath in the air. There is also interest in monitoring a small number of outdoor venues. Firstly, to assess the outdoor airborne transmission due to audience exposure whilst seated or standing and secondly, because outdoor venues always include many indoor spaces that should be assessed, such as ticketing, waiting areas, refreshments, toilets and other facilities. 

We will monitor CO~2~, temperature and relative humidity in the occupied spaces to understand air movement and ventilation performance during pilot events. We will also carry out microbiological swabbing and investigate crowd behaviour at the chosen sites. We will use this data to determine a Relative Exposure Index (REI) for each venue. This is not an absolute measure of the risk of transmission, but a measure of exposure at the event, relative to a benchmark case of working in an office space for several hours in a day. In the short term, the study will only investigate the environmental conditions as a result of the intended operation of the pilot events; we will not undertake parametric studies as part of this phase of the work. The intention is to continue our relationship with the venue and events operators so that a more informative, longitudinal study can be undertaken. 

Methods

The first priority is to carry out active monitoring at live events as they occur (measurements carried out by the research team on site during the event) and passive monitoring (measurement devices placed in advance around the venue, for several weeks of data collection during a number of events), and to report rapidly on associated risks and mitigations. However, to support our project research goals and improve the knowledge base in the field of airborne transmission, we would be keen to return to the venues to conduct follow up studies after the events. 

For each venue monitored we will analyse existing HVAC systems and risk assessments deployed by the venue operator, and we will collect data on physical parameters related to airborne transmission: CO~2~ (as a proxy for exhaled breath and poor ventilation), temperature, and relative humidity. This will be done at high resolution at key points throughout the domain to gain an understanding of air movement and ventilation performance during pilot operations (pilot studies as determined by the venue operator in collaboration with DCMS). The results of the measurements will immediately identify any potential higher risk settings, locations or activities, and will provide input into the REI which will be generalisable and used to produce guidelines in understanding and assessing risk in other scenarios/venues. 

The REI:  We use a mathematical model and a statistical framework to estimate uncertainty (how far estimated values might be from the true value) in the number of SARS-CoV-2 genome copies deposited in the respiratory tract of a susceptible person over time in a well-mixed indoor space. By relating the predicted median for a reference scenario, such as an 8-hour day in a 20 person office, to the scenario for a venue/event of interest, an REI is established as a function of space volume, viral emission rate, exposure time, occupant respiratory activity, and room ventilation. This reduces the need to understand the infection dose probability. An REI>1 indicates that the scenario for the location of interest is more risky than the reference scenario, and an REI<1 indicates that the scenario is less risky. We do not use a single number for each input parameter to our model. Instead we use a confidence interval for each input, where the two numbers indicate a range of inputs of which we are 95% confident of occurring.

The results of the measurements will also be used to inform and validate computational modelling of ventilation and of detailed airflows (via first order models and Computational Fluid Dynamics, respectively). The modelling will be carried out as part of project AIRBODS and will not be completed within the timeframe of the Events Research Programme, but will draw upon its results to inform the research community to improve future design and operations.

Although our main focus is air, we will also carry out microbiological swabbing and analysis. Microbiological samples will be collected from high-touch points within the venues. The samples will be examined for general bacterial contamination, to assess the level of cleanliness, as well as for the presence of SARS-CoV-2 (although it is very unlikely the virus will be detected on site as levels in the community are very low and pre-event asymptomatic testing will reduce the likelihood even further). Air samples will also be tested for microbiological content, to complement the air quality data in selected areas within venues where occupancy levels (the number of participants present in a single space) are higher. Relating both microbiology and CO~2~ to viral loads is not possible at present but this environmental data will contribute towards building a more complete picture of exhaled breath in the environment. 

We will also investigate crowd behaviour at the London based sites to analyse the underlying parameters relating to occupancy in various spaces. Through video analysis, we will quantify: 1) occupancy in different spaces of interest 2) people’s movement/aerobic levels, 3) interpersonal distances and interactions, and 4) compliance of face mask wearing. These results will inform the REI.  The video analysis will use deep learning algorithms and tracking techniques. Ethics approval has been obtained via UCL and the researcher responsible has extensive experience of these from his background in transport research and on Covid project VIRAL. 

Venues of interest

The list of venues we will work with in Phase one:

1. The Crucible, Sheffield – the World snooker championships, 17/4 - 3/5 

2. The O2 arena, London - The Brit awards, 11/5 

3. Wembley arena, London - The FA semi-final cup, Carabao cup and FA final cup, 17 - 25/4 – 15/5

4. Circus nightclub, Liverpool – 30/4 - 1/5  

5. ACC Business event, Liverpool – 28/4

Arrangements with venues

We understand that DCMS will lead on obtaining necessary agreements from venues to allow us to work on site. Venues would be responsible for H&S whilst our team is on site.  We will agree a plan of how to deal with sensitive data if such arises. Public comms protocols will be agreed with the venue and DCMS (via the Science Board) before their release and so will arrangements for further publication of the technical details. 

Venues and organisers will be required to provide us, as soon as possible, with detailed information about their site and their planning, to facilitate a fast discovery and planning process. These requirements are outlined in the appendix below. 

Large venues will be expected to allow us to install equipment to remain on site for a few weeks, as well as facilitate our live monitoring during events with a small number of the research team attending on site. We may request access to the site over a few days in order to set out our equipment. We require practical help from venues in terms of logistics of the field studies, such as storage space, parking, named contact people and assistance with fixing equipment inside the venue. 

Requirements for information from Venues

Drawings of the site will be needed before the first live event to help us plan the locations of our instruments. Other information may be obtained soon after to inform the REI model. 

This will include drawings of the site (ideally as built floor plans and elevations) as built mechanical ventilation schematics and specifications if available, building log books, other relevant information from the operation and maintenance manual and any environmental studies previously conducted or Building Information Data (BIM) if these are available. We request that they share with us their risk assessments and in particular their Covid related risk assessments and operational plans. We will also require information on typical dwell time and occupancy in each zone of the building during the events being proposed, for example how long people remain at the venue, how much time they spend in the bar or ticketing hall, etc (we understand that this information may need to come from the organisers rather than the venue operators). 

Detailed technical data required from venues (draft):

			notes
As Built drawings	Floor plans	Architectural	to estimate space volume
As Built drawings	Sections	Architectural	to estimate space volume
As Built drawings	Elevations	Architectural	to estimate space volume
As Built drawings	Air tightness line drawings	Architectural	To see if there may be air leakage between zones
	Marked up plan drawing showing typical dwell time for occupants in each zone during proposed event.		For RRI estimation
	The dwell time might be different for different groups, eg staff and spectators.
	Indicate typical activity eg seated, standing, how much talking/singing eg 25% time talking
As Built drawings	Ventilation schematics	Mechanical	To assess airflow per zone
	Marked up ventilation schematics with typical airflow per zone		To assess airflow per zone
As Built	Mechanical specification	Mechanical	To understand design intent
As Built drawings	Lighting schematics	Electrical	To assess heat loads
As Built	Electrical specification	Electrical	To understand design intent
	BBC lighting and camera layout schematics	BBC	To assess heat loads
	M&E Building log book	M&E	To understand design intent
	Access to Operation and Maintenance manual	Client/Main contractor	To understand design intent
	Access to BIM model	Client/Main contractor	Could help with modelling