When trying to determine how long a person can safely live in a moldy house, it is first important to determine the individual sensitivities of the people involved. In general, a person can live in a house infested with mold for several years, although some people may experience serious discomfort. For example, if you have asthma or mold allergy, you may have frequent asthma attacks or painful allergic symptoms, such as dark rashes, severe itching, sneezing, and general malaise. If you have a strong immune system and are not sensitive to mold, you may not notice any symptoms.
Exposure to black mold can be harmful in the long term, especially in people with respiratory conditions and other risk factors. Black mold can be one of several different species of fungi, including Stachybotrys chartarum. In small quantities, mold spores are usually harmless, but when they fall into a damp place in the house, they can start to grow. When mold grows on a surface, spores can be released into the air, where they can be easily inhaled.
If you're sensitive to mold and inhale a lot of spores, you could experience health problems. Other recent studies have suggested a possible link between early exposure to mold and the development of asthma in some children, particularly among children who may be genetically susceptible to developing asthma, and that selected interventions that improve housing conditions may reduce asthma morbidity and respiratory allergies. Another characteristic of black mold (and any type of household fungus) is that it can grow in hard-to-reach or little-visited places, such as behind closets and under floorboards. Whether it's the viscous black spots on the shower curtain, the blurred white spots on the basement floor, or the slippery orange film that forms on the kitchen drain, household mildew is more than unsightly.
If you have black mold in your home that is contained in an area small enough to get rid of it enough, this will likely solve the problem (although you'll need to keep an eye on it). The hazards posed by molds that can produce mycotoxins should be considered the same as other common molds that can grow in your home.