What level of humidity is appropriate? The Canadian Lung Association recommends a relative humidity in the home between 30%-50% for most of the year...any more can promote mould growth and we don't want that. Trying to maintain an average of 40% relative humidity in the home is nearly impossible in western Canada, especially during the cold winter months. It is very important to follow the guidelines on your humidifier, and to invest in a good humidistat to monitor your levels.
If you are finding too much humidity in your home, some options you have are replacing your windows with double pane, have an energy asssessment done in your home, run kitchen and bathroom vents a little longer after use, open windows everyday slightly just to let your house breath. Ultimately though, as it gets colder outside, you will have to lower the humidifier (maybe even turn it off for a short time). This one of those good home maintenance tips that will help keep your home/investment in tip top shape.