Mold has always been recognized as a concern. In fact, even the Bible references mold and provides instructions on how to identify and remedy it, showing that people have long understood the risks of living with microbial contamination.
What has changed is the way our homes are built. Older homes tended to “breathe” more, allowing moisture to escape naturally. Modern homes, on the other hand, are built to be more energy-efficient and airtight. While this improves heating and cooling performance, it also means that when moisture or water intrusion occurs, it becomes trapped inside—creating the perfect environment for mold to grow.
Additionally, modern building materials are often more susceptible to mold. Lumber from new-growth trees tends to have wider growth rings, which makes it softer and more prone to decay than old-growth wood. Materials like drywall also provide mold with an easy-to-digest food source when moisture is present. In the past, even paints added protection—lead-based paints, while toxic, were highly effective at resisting mold growth. With their removal for health reasons, modern paints no longer provide that same resistance.
All of these changes in construction practices and materials make today’s homes far more vulnerable to mold growth than those of the past—so while mold has always existed, the conditions that allow it to thrive indoors are much more common in modern buildings.
