I did HVAC for some years in large buildings in Philadelphia. Was working when the whole Legionnaires Disease hit. Woke us all up.
We were always concerned that mold would grow in the moist area after the cooling coil inside of the HVAC units from the spray of the condensate on the coil. You learn pretty quickly that mold grows when the humidity if over 70%.
But, you also learn that virus thrive when the humidity is under 30%.
We were working inside of units that had room for 10 people to stand. these were whole building units that could move 90,000 CFM and serve 5 floors of an office building. I was involved mostly in pharmaceutical work so was inside of units that were as contaminated as the lab they served. We had to bunny up with the full suit and mask.
We didn't do anything without an engineer signing off and we brought every concern to both our health and the building's health to the engineers.
Another scientific principal is that RH is Relative Humidity. Heat the air, the humidity drops. Cool the air, the humidity increases.
Putting 2 and 2 together, outside, in the cold winter, there is no moisture in the air. Inside the air is warmed. drives humidity down. "FLU SEASON" = low humidity both inside and out.
Summer colds are from air conditioning drying the air too much and driving down the humidity.
not 'spring colds' or 'fall colds' but Colds that follow human activity.
So far, we have watched the current problem cycle. spread in the winter, dropped in the spring
when it was raining and we all had our windows open and had a humidity in the 50% range.
Then we saw the summer spike when we went indoors and turned on the air conditioning.
Now, it is warm enough to have the windows open and we saw the expected drop.
Anyone want to predict what what coming flu season will bring ?
If you address your home AND WORK humidity, and I am wrong, you live more comfortably.
If I am right, you have a better chance of living.
If you are involved with any buildings, talk to the HVAC or maintenance and the building engineer.
They want to be healthy and humidity control is a simple thing.