Indoor air quality in well-sealed and well-insulated homes declines due to a lack of what?

The correct answer is ventilation. In well-sealed and well-insulated homes, the lack of proper ventilation can lead to a build-up of indoor air pollutants and moisture, which negatively impacts air quality. Without adequate ventilation, fresh outdoor air cannot enter the home, and stale air, along with contaminants from cooking, cleaning products, and other sources, accumulates. This can result in health issues for the occupants due to the inhalation of pollutants or allergens. Proper ventilation systems ensure that there is a continuous exchange of indoor and outdoor air, thereby maintaining healthier air quality within the home.

While options related to natural light, air circulation, and humidity control play significant roles in overall comfort and living conditions, they do not specifically address the core issue of air quality related to the exchange of air. Ensuring good ventilation is essential for removing excess moisture and maintaining a healthy breathing environment, which directly correlates to indoor air quality.