for Cold Climate Housing and much more

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

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

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 RVQAIH (Réseau en ventilation et qualité de l’air intérieur des habitations) comprised of Heating, Cooling and Ventilation manufacturers and consultants, professional associations, gas and electrical utilities, and both provincial and federal government departments – and me, maybe because I worked on training with some of these people 40 years ago -- all sharing information and resources related to indoor air quality for housing.

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....

On several occasions during the pandemic, this highly qualified group has taken a close look at COVID and ventilation in habitations. I cannot speak for this group, but I can share some of the wisdom that I have been listening to. 

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. Good residential ventilation is good for the health of occupants – with or without a Covid pandemic -- and far too many homes do not have enough well circulated fresh air. 

Can ventilation totally protect us from Covid – NO. 

Various strategies of ventilation can reduce the risk of transmission of Covid and the negative effects of other pollutants, but not eliminate them. 



So what should we do about ventilation? 

When talking about the transmission of Covid, let’s keep things in perspective with their degrees of importance.  In a living unit (a home, an apartment, a condo), good continuous ventilation with some degree of fresh air, well distributed with clean filters will slightly reduce risks related to Covid (diluting pollutants) – sanitizing that air flow with things like UV light, Bio-Ionisation or Hydroxyl will reduce risks more (killing airborne microbes and viruses) – but within a habitation the primary defence is to work on not bringing Covid into the house in the first place.  This sends you back to the standard Covid protocals mentioned above.

Getting ventilation on your side falls into 4 areas.


Basically we need more fresh air inside the house.  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 range hood fan regularly.  When you get tired of doing that, consider having an air change system installed.



Furnaces and air changers can 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 them running 24/7.  

However, filtration has very little to do with controlling viruses.  The virus that causes covid is so small that it passes right through the best of filters.  Unfortunately, schools and institutions have come to believe that HEPA filtration will make the air safer.  It will make the air cleaner with respect to many particle size microbes and pollutants, but viruses go straight through.  High quality filters also have the negative effect of slowing down air flow, hence requiring larger fans and more electricity to get the same quantity of air flow.  Many good air purification systems have no filters or only very open “cat hair” filters but good air sanitation elements, giving a far better response to the Covid crises than concentrating on expensive filter replacement.  This becomes especially important in large central ventilation systems. 





Ultraviolet light of the right intensity and for the proper duration of exposure does kill microbes and viruses including the virus that causes 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 pollutants 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.

The great limitation of UV germicidal lamps is that they only sanitize air that flows through the duct system; it has no direct effect on the rest of the air in the house nor does it deal with germs or viruses on surfaces in the room.



Hydroxyl generators are probably the best use of UV light for sanitizing because they work on the whole house, not uniquely on the air passing through the ducts.  Rather than acting directly on microbes or viruses, the special UV lamps reproduce indoors what the sun does outdoors, they break apart moisture molecules (H2O) creating Hydroxyl molecules (OH).  OH is a strong oxidizer that destroys pollution molecules, part of why outdoor fresh air is fresh.  Especially important for ventilation systems is the fact that although the hydroxyl molecule itself does not last a long time, it creates a cascade of other natural oxidizing molecules that do last for a long time and float all around your house, eliminating microbes, mould and viruses in the room air and on surfaces, just like outdoors.  Following manufacturer’s instructions on the size of the machine, air circulation and size of space, they destroy 99%  of the viruses that cause Covid-19 in the air in 20 minutes and 99% on surfaces in 60 minutes. Very through independent testing showed that after 8 hours, the viruses were undetectable.  Most other air sanitizing systems produce some ozone.  In the hydroxyl machines the light is strong enough to destroy any ozone as it is produced, projecting no ozone into the room. You get all this sanitizing power and it is all safe for humans, pets and plants. 

They can be put into central heating systems or made as stand-alone units.  Run them 24/7 – properly sized they can’t hurt you. 

Presently it is difficult to find residential units because the manufactures are concentrating on large machines for schools, hospitals and businesses but they are becoming more available.  Because of the extensive research they have undertaken, the Pyure Air Company is the leader in this field with machines making more hydroxyl than the competition and easily ambient hydroxyl levels equivalent to the sun's action outdoors.  For a thorough understanding of hydroxyls and hydroxyl generators, follow this link.



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.  This is often referred to as Bio-Ionization.  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 powerful enough to actually do good, although primarially for institutional and commercial use, is GPS (Global Plasma Solutions) with lots of good information on their site. 



This one is complex but it is one thing you can control in your house right now -- 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 thrive in both extreme dryness and extreme humidity. Click on the graphic to enlarge it.

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. Follow this link for details on window condensation related to outdoor temperatures.

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.  These are strategies that are simply good for healthy living, and especially important during this pandemic.

Jon Eakes


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

Article 2309