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Find out how to mitigate against aerosol transmission.

Covid-19 can be spread by people breathing in contaminated droplets. Evidence suggests that these are most likely to accumulate in poorly ventilated enclosed spaces where an infected person has visited. The University has put in measures to reduce risk by identifying areas that are potentially poorly ventilated and implementing arrangements to reduce risk. We have also made alterations to our mechanically ventilated buildings to actively improve air quality.

The following guidance sets out what we have done to reduce risks associated with aerosols and the steps that you can take locally to mitigate any residual risks.

Planning office spaces

We have developed normal occupancy figures for all offices. These are based on providing an appropriate amount of floorspace, per person, per room. Our space allocation takes account of any furniture and storage, as well as the space required to move around. This approach provides a natural element of distancing. The number of people normally working at any one time in that space reflects the number of people who should routinely work in a space; this should not generally be exceeded. It does not include people who may visit spaces for short duration meetings (meetings under 1 hour). We have produced separate guidance to outline the principles for holding meetings in office or hybrid spaces (link to meetings guidance).

Wherever possible, close contact face-to-face working should be avoided; side-by-side or back-to-back working should be preferred. If face to face contact is unavoidable, such as at reception desks, you may want to consider whether screens between workers or workstations can be provided. You might also want to consider whether other solutions, such as digital delivery of some services, might be preferable.

Planning teaching spaces - centrally and departmentally managed

  1. The University has identified that mechanically ventilated spaces are within SAGE ventilation guidance on Covid transmission risk and can return to pre-COVID capacities. However, hand hygiene and cleaning routines still need to be in place.
  2. Many of our naturally ventilated teaching spaces can also return to pre-COVID capacities. However, in order to provide continued reassurance, it has been agreed that:
    1. Flat room layouts will be planned with a 2m zone between the Lecturer and the first row of desks. . This rule has been applied in room layouts for central timetabling.
    2. A distance of 850 mm will be kept between rows of desks, where possible. This will result in a centre desk - centre desk distance of at least 1300mm. Keep chairs in a desk row 600mm apart. This will provide more space per occupant than previously existed in these spaces and also forms the basis of principles used to create the central timetable.
    3. Windows should be kept open. In colder months, wherever possible, use vents, partially open windows or high-level windows to balance ventilation with thermal comfort. Having windows even slightly open will provide ventilation which is better than having no ventilation at all.
    4. Where practical, rooms should be aired between lectures or activities. This can be achieved by opening windows between lectures to purge the room. Ideally, purging should be for at least 10 minutes after rooms are emptied with doors and windows left open.
    5. Continue hand sanitisation and desk wipe-downs, before and after usage, and allow individuals to wear face coverings. Where naturally ventilated rooms are identified as having parts that may be poorly ventilated then we will reduce overall occupancy to reflect the fact that there is less usable space. This will be reflected in timetabling.
  3. Workshops and labs with local exhaust ventilation (LEV) such as fume cupboards can be used at pre-COVID capacities, subject to risk assessments confirming such systems are in working order and are providing appropriate levels of ventilation.
  4. Purpose-built PC labs should be designed with mechanical ventilation, however, rooms re-purposed as PC labs may not have adequate ventilation and you may wish to request a ventilation assessment. See details below re support for departments.

Planning study spaces

The above guidance also applies to student study spaces. Some spaces will be designated ‘face covering required’ zones to cater for those who would prefer to study with a face covering or clinically vulnerable students.

Guidance for use of study spaces is as follows:

  1. we will expect/recommend library users (unless exempt) to wear face coverings when moving around the building and when in a timetabled teaching session
  2. we will create a clearly designated space for those who prefer to study with a face covering and would prefer others around them to do so too
  3. hand sanitising and desk cleaning materials will remain, and their use will be encouraged additionally, in the library, one-way systems for and exiting will remain and
  4. staircases will have two-way traffic flows, managed with ‘Keep Left’ protocols.

Planning research spaces

Workshops and labs with local exhaust ventilation (LEV) such as fume cupboards can be used at pre-COVID capacities, subject to risk assessments.

In determining office space occupancy rates, PGR students are considered staff so departments should aim to not exceed a rooms ideal normal occupancy where possible. It is understood that this may be aspirational in some departments, however you may wish to look at the Future Ways of Working programme for ideas on how to use your space differently. Please refer to the room normal occupancies data to determine problematic rooms and advice for exceptions as outlined here (link to exceptions).

Ideal room layouts

The following examples show ideal layouts for rooms that will avoid staff having to work in close face to face contact. Where this cannot be avoided, the use of modesty screens may be an option. Alternative options may be occupying the space at a lower occupancy using a rota system.

Examples of good departmentally controlled GTA space layouts:

A GTA space layout diagram A GTA space layout diagram

Examples of good office layouts:

An office space layout diagram

Defining space occupancies

Definition Description Activity Rationale
Teaching room occupancy The number of students being taught in a room People sitting in fixed rows (not facing each other) and largely listening. Based on a distance of 850 mm between rows of desks, where possible. This will result in a centre desk - centre desk distance of at least 1300mm. Keep chairs in a desk row 600mm apart.
Maximum normal occupancy for offices The maximum number of people who would expect to spend their working day in that room – this is based on statutory minimums. People sitting at desks and moving around the space informally/ randomly throughout the working day. Based on 11m3/2.5m ceiling height = 4.4m2 per person. There is no requirement for others to leave the room if a visitor arrives.
Meeting room occupancy The maximum number of people one should plan for in a meeting of 1-2hrs People largely confined to specific seats for a defined period, conscious of their spacing. For meetings in offices, a similar rationale may be applied. Based on 2m2 per person. Ventilation should be maximized as far as possible whilst ensuring that thermal comfort is not compromised.

Maximum normal occupancy: The maximum number of people who can routinely work in a room at any one time. This number is based on statutory minimum amount of space required per staff member, defined by HSE guidance as 11m3 per person. We have approximated this to 4.4m2 per person, based on an average ceiling height of 2.5m. You should not exceed this maximum normal occupancy while planning your departmental space.

For the purposes of health and safety legislation, Postgraduate Research Students are considered workers when carrying out their PGR studies; for this reason, the guidance above relates to PGR write up spaces, too.

One-way traffic flows in buildings

We recognise that one-way systems have presented some operational difficulties to some departments and that these may require some alteration. Departments will have the best knowledge of how their buildings are used, so we are asking that individual departments propose where one-way systems and other arrangements can be removed.

When making your proposals on one-way routes in your buildings you should consider: 

  • Likely largescale movement of people at the same time, such as at the end of lectures or large meetings
  • Pinch points in corridors and areas where people are likely to come into close contact
  • Operational requirements to move materials, equipment, and other items around site
  • Which signs should be removed or retained

Once you have completed your proposal, this will need to be shared with Estates for consideration and to action any alteration to the signs. If departments require assistance in determining whether one-way systems are necessary, they should contact the health and safety team for advice. You can get in touch with both teams via the CSR TopDesk tile. 

Explanation of Ventilation Assessment

Small droplet aerosols, breathed out by infected persons, can accumulate in poorly ventilated rooms. If other people breathe these in, then it is possible that they could themselves become infected. We have carried out an initial ventilation assessment of all spaces to identify any areas where we think that ventilation may be below desired levels. We are measuring these spaces and where ventilation provision looks poor, we will down-grade occupancy levels and tell you why.

This assessment informs us that certain parts of a room may have lower levels of ventilation. These are the spaces furthest from windows which we recommend are used for storage or circulation.

In our desktop exercise, we assumed that all single occupancy offices have a supply of fresh air. If you are aware of any such spaces with no visible signs of ventilation (whether mechanically or naturally), let us know and we can investigate further. If you have any concerns about any of your spaces, please report this to Estates via the CSR TopDesk tile. We expect this to be a dynamic process and we will continually be assessing rooms as and when required.

Managing ventilation vs thermal comfort

Where offices rely on opening windows for ventilation, then these should be open whenever the office is occupied. In winter, it will be important to balance ventilation against other concerns, such as thermal comfort. Windows do not have to be fully open all the time; having the windows, including high-level windows open, even a little will provide fresh air.

If draughts are a concern, then desk layouts may need to be altered.

Reporting stuffiness

Please advise your staff that if they have concerns about ventilation in their workspaces, they should first consider opening windows and doors to improve airflow. However, please remember that doors marked as fire doors should not be wedged open. If the issue is persistent, contact Estates via the CSR TopDesk tile for advice. Where necessary, they can arrange for reassurance monitoring to be carried out and depending on the findings they will make recommendations on how the situation may be improved.


If you have any further enquiries, please get in touch via the CSR TopDesk tile.