Reducing the risk of COVID-19 spread with good ventilation

As the weather gets colder, more of your customers will move inside which, along with expanding numbers of COVID-19 positive people in the community, increases the risk of people contracting the virus on your premises.

Even if you could guarantee 2 metres safe distancing between customers and staff, micro-droplets from an infected person coughing or talking can remain in the air for at least three hours and could potentially infect someone else.

How can ventilation prevent COVID-19 spread?

 It is still not known how many viral particles are needed to cause COVID-19, but good ventilation will dilute or remove viral particles in the air and thus reduce the likelihood of COVID-19 spread.

What simple steps can be taken to provide a good supply of fresh air?

• Increase the existing ventilation rate by adjusting the fan speed
• Keep the ventilation switched on whenever there are people in the building
• Monitor and manage filters according to the manufacturer’s instructions
• Keep doors and windows open if possible
• Use ceiling fans to improve circulation if there is a good supply of fresh air
• Avoid locating fans where they may move air between people’s breathing zones

How do you know if your ventilation levels are sufficient?

When you walk into a room and it feels stuffy or the air smells stale, it is the first indication that something is wrong with the ventilation and most informed customers will walk away at that point. The use of the room will determine the number of recommended air changes per hour. You should consult a competent ventilation engineer if you are unsure if these levels are met.

Do air conditioning units reduce the risk of COVID-19 spread?

It depends on the type of unit. Split air conditioners (typically a white box mounted on walls or ceilings) draw in air from a room, chill it and then blow it back out again. In other words, they just re-circulate (potentially contaminated) air.

In fact, these type of units were implicated in a COVID-19 outbreak that originated in a restaurant. Virus particles from a pre-symptomatic COVID-19 carrier at one table released as he talked were pushed around the room by swirling air currents from the units on the wall. As a result, nine other people at other tables became infected. If, however, there had been a good supply of outside air, fewer (if any) people would have become infected.

Air conditioning systems which recirculate air between rooms can also increase the risk of COVID-19 spread.

How do you get enough fresh air into a room with sealed or no windows?

You will need a ventilation system that extracts stale air from the rooms and pipes it to an air handling unit, often on the roof. There, fresh air can be pulled from outside and mixed with the old inside air, before being sent back into the building.

Adjusting the precise mix of air to maximise the percentage of outside air will reduce the risk of recirculating the virus through buildings. However, there is an energy cost as incoming air must be heated in winter and cooled in the summer.

Do ventilation filters trap the virus and prevent COVID-19 spread?

Although it is claimed that HEPA (High Efficiency Particulate Air) filters installed to purify the air will trap the virus, there is research to show that not all filters are fool proof. Filters should be changed according to manufacturers’ instructions, and care should be taken when doing so as they may be contaminated with the virus.

Where can I find advice on suitable ventilation systems?

If you want to ensure that you are following best practice, you should consult a competent ventilation installer who is aware of the latest COVID-19 Ventilation Guidance from CIBSE (Chartered Institution of Building Services Engineers). You can download the guidance here.

Safer Food Scores COVID-19 compliance consultants provide COVID-19 management systems which include risk assessments, safe methods, monitoring records and signage. Your COVID-19 checks can be digitised using our health and safety monitoring app available for iOS and Android devices. We can also help you achieve COVID-SAFER UK accreditation which would give your staff, customers and visitors confidence that you are following best practice. Please contact us on hello@saferfoodscores.co.uk for more details.

Any guidance given in our articles is not official and Safer Food Scores can take no responsibility if the information is used to form part of any legal or regulatory compliance for your business. However, please do get in touch if you are interested in our support services and would like to benefit from official guidance relating to your particular circumstances, email [javascript protected email address]