What should schools do to prevent the spread of SARS-CoV-2 in classrooms

Masks provided decent protection against the SARS-CoV-2 but if a carrier of the virus (40% of them are asymptotic) stays inside a home/business for a long time then the chances of transmitting the virus are higher because some particles may escape.

According to experts the best way to prevent the spread of the virus is to keep introducing fresh air inside a room.

Unfortunately, most rooms don’t meet the recommendation of 8 air changes an hour for a 10 square meter (107 square foot) room occupied by 4 people. A clear example is a classroom that doesn’t meet the recommended ventilation rates. This is a common mistake across all schools in the world.

Schools have two options to bring fresh air into the classrooms from outside or remove the virus from the air inside the classrooms with the help of ventilation systems that can potentially kill the pathogens thanks to UV-C rays but this is a different subject and we will discuss it on a different article.

A wise move for schools will be to invest in Carbon Dioxide (CO2) monitors because they will help them calculate the ventilation rates for each classroom. The CO2 concentrations can help us estimate if enough fresh outside air is getting inside the classrooms.

Outside, a low-cost CO2 can measure a concentration of about ~400 ppm, which unfortunately it is the new norm, indoors the CO2 shouldn’t surpass the ~1000 ppm. Many studies demonstrate how high CO2 concentrations decreased our cognitive abilities so we can have double benefits when we monitor the CO2 indoors and try to keep it low.


A CO2 monitor can give a great indication of the air inside a room and it is relatively an inexpensive investment with multiple positive benefits for schools and students. It is important to take control of the indoor environment if we want to keep winning the fight against coronavirus.

There are a lot of great solutions in the market, Airhings Wave Plus, Airthinx IAQ, Awair, Laser Egg + CO2, uHoo, Djinn sensors, uRAD monitors, Air Gradient – School, Airly to name a few.

Air Gradient – School

6 thoughts on “What should schools do to prevent the spread of SARS-CoV-2 in classrooms

  1. In my opinion, introducing ambient air into indoor spaces will also bring particulates which are supposed to be carriers of SARS-CoV2.
    Also, monitoring CO2 levels cannot be surrogate to configure Viral or microbial load in air.


    • Many ventilation systems have Hepa filters build in (or are upgradable with it) so that you would have low particle amount inside.
      Also in Asia more and more schools Are building positive pressure fresh air systems into the classrooms that also have Hepa filters and are often an easy upgrade to the existing air condition systems.

      Liked by 1 person

  2. If everyone wears masks or face coverings then the risk of transmission is low. Yet how can you expect such of children. Opening of windows is fine now, in some European cities perhaps, but in Scotland the windows will have to be shut pretty soon. As to HVAC system in Schools not in the UK, and certainly not with HEPA, I bet very few schools have real HEPA filters throughout the world in their HVAC systems. Finally particulates carrying SARS-CoV-2 is a myth.

    So your solution makes sense, but won’t work in a few months time in the UK (or many European cities) winter months!

    Liked by 1 person

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