Ventilation and air filtration play a key role in preventing the spread of COVID-19 indoors.

The covid pandemic has complicated the past few months. Recently a decision has been made to reopen offices, stores, and schools as cases decrease in some countries.

However, there are still many measures to be implemented so that our activities do not mean a risk for everyone. Building managers are researching to reduce SARS-CoV-2 particles in the air we breathe.

What are ventilation rates and air exchange, and why is it essential to COVID-19?

The ventilation rate is the volume of outdoor air provided per unit time, and the air exchange rate is the ventilation rate of a space divided by the volume of that space. What does this mean? The air exchange rate tells you how quickly you can clear a room of any airborne contaminants, which is important in the case of coronavirus because if you can quickly clear any airborne viruses, you will reduce the risk of transmission.

Most air conditioning and heating systems circulate about 20 percent of the fresh air in a building while recirculating the remaining 80 percent or energy efficiency.

What was the recommended ventilation rate before the pandemic?

For a 1,000-square-foot classroom designed for 35 people, including teachers and students, ASHRAE recommends a ventilation rate of 500 cubic feet per minute of outdoor air. During a pandemic, this rate should be doubled.

Similarly, experts recommend reducing space occupancy to improve air quality during a pandemic. One of the best ways to reduce the risk of transmission is to reduce the number of people in an office or classroom. 

This allows for social distancing that minimizes the risk of transmission through close contact and reduces the number of infections likely to occur if an infected person is in the classroom. 

As an added benefit, more outside air is provided per person, contributing to better overall air quality. In other words, if the number of students is reduced from 35 to 17, ventilation provides twice as much outside air per person, and that’s important.

Ideally, your office or school should make multiple improvements. 

For example, include a certified HEPA air cleaner that is the right size for the room. A HEPA filter can remove more than 99 percent of the particles in the air that pass through it.

It is also a good idea to open windows when possible to allow fresh air in and out as this dilutes the virus concentration.

Fans should be positioned to blow out the air and avoid blowing air around the room, which could spread the virus.

Improving HVAC filtration of indoor air decreases the risk of VOC-19.

As mentioned, air filters play an essential role in improving indoor air quality. While you want to increase the amount of outdoor air that is brought into the room, you must also filter the recirculated air. 

The minimum efficiency report value, or MERV, is a rating that reflects how efficiently a filter can collect particles of different sizes in a single pass. The higher the number, the better filtration a room will have. Mechanical filters increase their efficiency as particle size becomes more extensive. Due to diffusion and electrostatic attraction, their efficiency also increases as the particles become smaller.

If you have doubts about this, it is helpful to ask your office building manager or school representatives if air conditioning filtration has been improved.

We are working hard to create a safe environment for everyone.


As different governments strengthen their masking ordinances, at We Shield, we work hard to create a safe and clean environment for our front line workers and individuals at most risk of contracting COVID-19. We are sourcing and distributing top-quality personal protective equipment and safety supplies at the best pricing on the market.