Examples of improving ventilation to reduce coronavirus (COVID-19) transmission

The latest advice on keeping workplaces safe will help you assess the risks and continue to reduce COVID-19 transmission.

Portacabin with air conditioning

Office staff work in a portacabin adjacent to a main factory. The portacabin has a recirculating air conditioning unit. The windows aren’t normally open.

There are usually only a few people in the portacabin but they’re joined every morning by the factory’s administrative staff for a meeting.

Up to six people work in the portacabin from 9-5pm. As windows and doors aren’t usually open, there isn’t enough fresh or clean air into the space.

Changes to achieve adequate ventilation

  • Staff now open windows on both sides of the building every day to create a crossflow of air. This introduces more fresh air than opening windows on one side of the building
  • As the desks are free-standing, workers can move them slightly further away from the windows to maintain a comfortable working temperature
  • The business uses a recirculating air conditioning unit and portable convector heaters to maintain a comfortable working environment when temperatures are extreme
  • The morning meeting has been moved to the main factory unit where there’s a larger ventilated space

Canteen with mechanical ventilation system

A factory canteen has a mechanical ventilation system. It meets current building standard ventilation requirements. The business has grown in recent years and the canteen is now too small for the number of people using it at the same time. This means there are long queues at the food counter and every seat is full.

When the canteen is crowded, workers are very close to each other. This increases the coronavirus droplet transmission risk which good ventilation will not prevent.

Changes to achieve adequate ventilation

  • The business has reduced occupancy of the canteen by staggering lunch breaks. This means that the canteen is not too crowded when workers are waiting to be served at the food counter or while seated at a table. The existing ventilation system is suitable for the space and minimises the COVID-19 transmission risk

Changing room with poor ventilation

A changing room in a production facility has no windows that open and no mechanical ventilation. Workers reported to management that the room felt stuffy. Different staff use the changing room frequently, especially at the beginning and end of shifts.

Changes to achieve adequate ventilation

  • The manager found that the room did feel stuffy, indicating that the ventilation was not good enough. They needed to get fresh air into the room.
  • The trickle vents at the top of each window were closed. Opening them all would let some fresh air into the room, but additional arrangements needed to be put in place.

The business has found an alternative space for staff to change. They now use another larger room with windows that open. Workers are instructed to open the windows wide between uses to let fresh air into the room.

Production space with extraction fans

A large production hall with a high ceiling has extraction fans mounted in the roof. A large roller door at the front of the space is frequently open for deliveries. Occupancy is not very high but most people work in one small area of the hall where they inspect finished products on a conveyor belt.

Changes to achieve adequate ventilation

  • Overall ventilation in the production hall is sufficient. However, the ventilation doesn’t mitigate the aerosol transmission risk in the area where the worker occupancy is high
  • The business has redesigned the workspace so that workstations are spread out across the production hall and the aerosol transmission risk is reduced. The business has not had to make any changes to ventilation in the main production hall

Office with mechanical ventilation

A large office space has a mechanical ventilation system that provides heating and cooling. It’s set on 80:20 recirculating to fresh air intake. The business doesn’t know how to alter the settings to allow for more fresh air or if the system is already delivering a suitable amount of fresh air to the office workers.

Changes to achieve adequate ventilation

  • The business needed a competent ventilation engineer to help them
  • A ventilation engineer checked the system performance and found it had deteriorated as the business hadn’t maintained it for a while
  • The engineer has done some remedial work and checked the system now meets ventilation requirements in current building standards
  • This means the business can meet ventilation needs and can operate the mechanical ventilation system on 100 per cent fresh air intake

Office complex with air conditioning

A large office complex has air-conditioned meeting rooms. The facilities manager has found out that the air conditioning units do not draw in fresh air. Instead, they recirculate air within the rooms to provide thermal comfort.

There is a high risk of airborne coronavirus transmission for people using the meeting rooms.

Changes to achieve adequate ventilation

  • The business provides some ventilation in the short term by opening windows
  • As all the windows have security stoppers to restrict opening, the business now supplements the natural ventilation by using portable air cleaning units to filter the air
  • There are now four portable units to service the volume of air in the main office space and additional units for each meeting room
  • In the longer term, the business is considering mechanical ventilation for the office area when everyone returns to work in the premises

The business has considered increasing natural ventilation but rejected this as the meeting rooms are next to a noisy main road. Noise from the traffic would mean staff would close the windows. This means opening the windows isn’t a suitable long-term solution.

Packing room with mechanical ventilation

A chilled packing room in a food production facility maintains low room temperature by operating the mechanical ventilation system on full recirculation mode.

This means there is poor ventilation and a high risk of airborne coronavirus transmission for workers in the chilled packing area.

Changes to achieve adequate ventilation

  • As a short-term measure, the system has been operated at its maximum fresh air intake. The company’s ventilation engineer informed them that the system was only capable of providing a maximum of 15 per cent fresh air intake. This has not met the minimum recommended fresh air per person working in the chilled room.
  • The ventilation engineer has now confirmed the system design can accommodate HEPA filters without impairing the airflow. These clean the air in the room by filtering out virus particles from the air which passes through the filter.

Meeting rooms with carbon dioxide (CO2) monitors

A company has CO2 monitors mounted on the walls of their meeting rooms. They give a rough indication of whether natural ventilation from open windows is sufficient during meetings.

The business has installed the monitors as workers have been concerned that air in the meeting rooms has felt warm and stuffy.

Levels of CO2 creep up during longer or busier meetings. They remain high for a long period of time – even after the room has been vacated.

Although the meeting rooms have been used within their design occupancy, the business has made some changes as a result of these CO2 monitor indications.

Changes to achieve adequate ventilation

  •  Meetings are now kept to a maximum of two hours
  • The rooms are purge ventilated/aired after use. The business has also set a suitable airing time between meetings
  • The business has also reviewed the CO2 monitoring in the meeting rooms. Contextual information is now recorded as well as the CO2 measurements. This information includes the number of occupants and whether windows are open or closed during a meeting
  • Managers have explained the need for good ventilation to workers. This means windows need to be kept open during meetings or at least periodically opened to introduce fresh air. The business has followed this up with supervision to reinforce the message
  • The company now plans to install mechanical ventilation in some meeting rooms which will increase the ventilation without needing to open windows