A contributing factor to winter breathing disorders may simply be a deficiency of moisture in household air. I have the advantage of heating with wood, so can add moisture to the air by keeping pots of water on the stove. Part of the daily routine is to keep filling the pot(s) with water. There is no fixed amount as outdoor weather conditions vary, but I can count on evaporation of anywhere from 10 to 16 litres per day. The difference in quality of life is quite pronounced and my family and I experience less sinus and lung congestion and much freer breathing.
I use an eight-inch convection fan (see photo) between the pots. It is silent and keeps hot air from simply rising toward the ceiling. The stove also has a built-in blast fan that is efficient on cold days. It’s noisy but some sort of fan is essential.
My way of measuring household humidity is simple. If moisture begins to accumulate on cold windows, I remove a pot. If houseplants show signs of low humidity, I put it back on.
Also, if you have hardwood floors or expensive wood furnishings, you should consider raising room moisture levels a touch in our “dry cold” winters. The last thing you want to see is drying cracks or constriction heaves in furniture or floors.
Commercial humidifiers are available, but if you heat with wood this is a no-cost, highly effective alternative. †