It depends. Mold particles are everywhere both inside and outside your home which is why you need a good furnace filter to help reduce mold and dust in your home. It is not possible to totally eliminate mold spores. That said you may need to be concerned when you find live mold growing in your house usually due to a water leak. Leaks can occur when a home’s exterior is not maintained well… roof, siding, or foundation. Live mold in a confined space can produce an elevated level of spores that carry toxins which can be inhaled causing health problems. Some mold is benign but others like Black Mold known as Stachybotrys is very toxic and can lead to serious health issues that many times are misdiagnosed. Toxic black mold produces trichothecene mycotoxins. As someone who has been exposed to Black Mold and currently undergoing medical treatment I can confirm this first hand. If you have ever lived or worked where there was known water leakage it is important to see a medical specialist to get tested especially if you are exhibiting symptoms that just won’t seem to go away. The longer a person goes without treatment the worse the symptoms can be even to the point of disability. Should you ever suspect that you may have mold in your home or place of work it is important to seek out a reputable environmental company to have your home tested. Better to be safe and “well” than sorry and sick!