Some of the factors and conditions that contribute to mold growth are difficult to control. These are the things that are normal functions of everyday living.
Simple processes such as breathing and perspiring contribute to the moisture in the area where it occurs. Crowded living conditions, or special events (such as parties) can also increase the moisture level because the number of bodies present are greater than normal. Normal activities in the home should not increase moisture significantly enough to trigger mold. However, in businesses such as gyms and indoor pools, the moisture and humidity levels can be high enough to create a mold-friendly environment.
Pets and plants also contribute to the nutrients in a home. And, sufficient nutrients are a contributing factor in mold growth. The dander and dirt combine with house dust to create a food source that helps mold thrive. Keeping pets groomed can cut down on the dander in the home, but will not completely eliminate it. Keeping plants dusted and not over-watering can help as well.