Keep Indoor Places Well Ventilated to Reduce Transmission
Five air changes will reduce the original airborne contamination to less than 1%
12th May 2020
As businesses begin to re-open and people return to work, studies have found that increased ventilation will help reduce the rate of transmission of COVID-19.
While airborne transmission is not thought to be a primary route of transmission, there is mounting evidence to suggest that SARS 2 CoV can also be spread through tiny droplets suspended in the air, particularly in poorly ventilated indoor spaces. As such, the government are recommending that building managers "keep indoor places well ventilated".
Public Health England’s guidance on infection control states that “the predominant modes of transmission are assumed to be droplet and contact.” Droplets from coughs and sneezes will generally fall out of the air-stream within a short distance; however, this is dependent on airflow speed and direction, which is why it is important to consider how ventilation might be best configured to control airflow and protect people from the risk of airborne transmission (CIBSE, 2020).
Negative pressure ventilation systems can be used to extract contaminated air out of a waiting room, a treatment room, or an entire ward. For example, RVT was asked to design a bespoke temporary ventilation solution to help reduce transmission at John Radcliffe Hospital. The existing ventilation system provided positive pressure, however it was decided that the hospital required a negative pressure system to keep the virus contained within the wards that housed COVID-19 patients. RVT supplied two different sized centrifugal fans (300m and 450s) to achieve 12 air changes per hour.
Doctors and Dentists
RVT have been in discussions with other healthcare providers who require temporary ventilation solutions in order to keep their staff and patients safe when they re-open. We have been recommending the Dustex Raptor with HEPA filtration, which is capable of providing negative or positive pressure, and will deliver 33 air changes in a 30m3 room (examples are pictured at the bottom of this page).
Public Health England explain that “a single air change is estimated to remove 63% of airborne contaminants... and after 5 air changes, less than 1% of the original airborne contamination is thought to remain”.
Many of our construction clients will be familiar with the Dustex Raptor as a dust extraction unit, however the Dustex Raptor can also be configured to provide positive or negative pressure ventilation.
To create a negative pressure: Locate the Raptor within the internal space. Fix the 3m x 250mm flexible ducting to the unit. Feed the ducting out through a window; the fishtail can be used to reduce the window opening. When switched on, the Raptor will extract the contaminated air from inside the room and vent it outside the room. The high airflow will maintain a negative pressure environment.
To create a positive pressure: Locate the Raptor outside the internal space and feed the ducting in through the window so that the unit operates in the reverse configuration. When switched on, the Raptor will force clean air into the room and force contaminated air out through windows and vents. The high airflow will maintain a positive pressure environment.
Supermarkets have remained open throughout the pandemic, however strict social distancing measures have been put in place to help reduce transmission of the virus. Experts from Aalto University in Finland have created a simulation to demonstrate just how easily germs can spread from a single cough in a supermarket.
On more than one occasion, RVT have been drafted in to provide temporary climate control and/ or ventilation systems to maintain ambient temperatures inside supermarkets throughout the seasons. The same ventilation solutions can be configured to create a negative/ positive pressure system in order to control airflow and reduce the risk of airborne transmission.
Shops, restaurants, cinemas, gyms, schools and other indoor buildings
RVT offer a wide range of ventilation equipment, delivering anything from 1000m3 to 120,000m3 of clean air per hour, meaning that we can keep your facility well ventilated no matter the size. Furthermore, we can offer dust and fume control equipment during maintenance or refurbishment works.
We work tirelessly with the rail, marine and construction industries to deliver temporary ventilation solutions all year round, and so we are well equipped to tailor a ventilation for any sector that may require our services.
Request a FREE Quote
If you are looking for a temporary ventilation solution to manage airborne contaminates during the current pandemic (and beyond), please give RVT a call on 0808 178 3286 and we will gladly provide you with free best practice advice and a no-obligation quote. All of our consultation staff are BOHS qualified and will be able to tailor a solution that meets your specific requirements.
Alternatively, view all ventilation equipment here.
Click here, to request a call back to discuss your requirements.
*This page was updated on 9th July 2020
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