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Last Updated: , Created: Friday, October 9th, 2020

Ventilation Strategies for Covid-19 and other air borne health problems

Posted October 9, 2020

Because of the seriousness of the issue, I want to take a moment to present my credentials other than that guy that has been on TV and radio for 42 years.  In the 1980’s I was one of the primary instructors for the R-2000 energy efficiency program teaching contractors across Québec through the APCHQ, the provincial home builder’s association.  Since then I have sat on CSA standards committees, been a member of the Canadian Home Builder’s Technical Research Committee for over 25 years, been involved in research and research dissemination for the National Research Council and the Canada Mortgage and Housing Corporation (CMHC). For the last few years I have participated in a Québec information sharing group, the RVQIH (Réseau en ventilation et qualité de l’air intérieur des habitations) comprised of Heating, Cooling and Ventilation manufacturers, professional associations, gas and electrical utilities, and both provincial and federal government departments – and me because I trained some of these guys 40 years ago -- all sharing information and resources related to indoor air quality for housing.

This last week this highly qualified group took a close look at COVID and ventilation in habitations. 

I have received a lot of questions from my CJAD radio audience about ventilation during this pandemic – does it makes things better – does it make things worse....

In the short time I have available here I can’t deal with all the research behind things, but I can give you the short list of results important to you at home.



Masks – social distancing – washing hands is the starting point as you hear constantly, although inside the privacy of our homes, washing hands regularly is the only one that remains a priority.



So what should we do about ventilation?  It falls into 4 areas.



Basically we need more fresh air inside the house, especially since, for the moment it is not artic cold outdoors.  Yes there will be an energy penalty, but right now we are talking about surviving the pandemic.

If you have a ventilation system, run it continuously 24/7 and in outside supply mode as much as possible. 

If you do not have a dedicated ventilation system but do have a forced air furnace, keep the fan on continuous operation at slow speed – what we often call summer ventilation mode. If your system has a make-up air duct, that will constantly bring more fresh air into your house.

If you have no ducting in the house – hot water or baseboard radiators – use the bathroom exhaust fan continuously or at least frequently.  This will draw fresh air in through air leaks in the walls.  Don’t have a bathroom exhaust fan, turn on the rang hood fan regularly.



Furnaces and air changers will circulate freshened air appropriately throughout the house.

If you have split head heaters or coolers, set the vanes to send the air out across the room at the ceiling, and not directly down on your heads – or should I say your lungs.

Improve the air quality

If you have any integrated or stand-alone air filter systems, clean or replace the filters at least as directed, if not more frequently.  Keep it running 24/7.





Ultraviolet light of the right intensity and for the proper duration of exposure does kill microbes and viruses including Covid-19.  But UV light is the same as the part of sunlight that can damage eyes and tan or burn skin, so you do not want to be exposed to any UV lamp.  For that reason UV air cleaning lamps are always encased inside metal boxes or inside the ductwork of a central heating/cooling or ventilation system.

The unit installed must be sized according to the volume and speed of air moving over the lamps to assure that the airborne viruses are appropriately exposed to the UV rays of the lamp.  This is the most easily available of the air purification systems.  Regular maintenance is required to keep the lamps clean.



If you have, or can procure, any corona discharge-negative ion machines or air cleaner machines with corona discharge, run them continuously.  Negative Ions do kill bacteria and viruses – and if strong enough they have now shown they can kill corona-19 viruses.  Corona discharge means that a high voltage charge is sent to a needle that creates a tiny lightening like discharge in the air creating negative-ions.  It got its name a long time before somebody named a virus -- “corona”.  Good corona discharge creation of negative-ions is the only way to avoid creating ozone at the same time. We don’t want ozone generators as they are corrosive to your house and your lungs. For a series of three articles on my site about Negative-Ions and health, follow this link.

One of the best of the manufacturers producing negative ion  generators for institutional and commercial use is GPS (Global Plasma Solutions) with lots of good information on their site. 



If you can possibly find an atmospheric hydroxyl machine, run it continuously 24/7 – although they are almost all sold out right now and the manufactures are concentrating on large machines for schools, hospitals and businesses, not on individual houses.  Hydroxyl is a naturally occurring oxidant that cleans the air outdoors.  Atmospheric hydroxyl molecules are produced by sunlight (or high energy light sources) striking water moisture molecules.  Machines have been perfected to do that better than sunlight and the molecules last longer for greater effect, and any ozone produced at the same time is destroyed by  the high energy light as it is produced – so no ozone comes into the room.  They can be put into central heating systems or made as stand alone units. Run them 24/7 – they can’t hurt you. But you won’t find much of anything available for the next six months. For a through understanding of hydroxyls, follow this link.



This one is complex but it is the one thing you can control in your house -- is Relative Humidity.  For a lot of detail about what is Relative Humidity, follow this link.  The reason that viruses and flue bugs are more active at the beginning of the heating season, is that our houses begin to dry out with the low relative humidity outdoors plus the heat in the houses.  When the spring brought in higher humidity, we got control of the virus, as we begin to heat our houses, the second wave more easily invades our dryer houses.

Here is a fascinating chart showing that many bad things that thrive in both extreme dryness and extreme humidity. 

50% is in fact the sweet spot where things are the least active with the least airborne transmission, and that includes Covid-19. 

Our problem is that most of our houses are not built to super energy efficient standards that could allow 50% RH in the wintertime without condensation and the growth of mold.  So we generally sit at about 30% RH, and get dry throats but no sweat on windows and no mold.

So for the pandemic, bring the humidity up in the house, up to right before where your windows start to sweat  Wipe the windows and window frames dry when they do sweat.  Work to avoid mold, but keep the humidity up. This is a compromise for this year, work harder at controlling humidity at the upper limits, to give us the least active viruses. 

If you have forced air heating, invest in a central controllable humidifier.  If you can’t do that, buy several stand up humidifiers and keep them running – and keep the water fresh in them and keep them clean.  More work but more comfort and greater Covid safety.  


I am not inventing this. I am reporting what the best minds in Québec are developing as indoor air quality strategies.

Jon Eakes


Keywords: Humidity, Air Quality, Relative Humidity, Air Flow, Air Changer, Air Filters, Ventilation, Health

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