I’ve heard that you can make a home “too airtight” – should I be concerned about this?

Today’s homes are more energy-efficient because they follow standards mandating better insulation and airtightness. However, without an appropriately designed, installed and maintained ventilation system, homes can be under-ventilated. Air leakage is not ventilation. A lack of controlled ventilation can lead to a build-up of moisture, odors, bacteria, fungi and combustion gases such as carbon monoxide, carbon dioxide and other pollutants. Ventilation prevents excessive build-up of these and other indoor contaminants that can affect your health and comfort and damage your home.