Mold and Mildew
Mold or Mildew is a type of fungus that can cause a stuffy nose, irritated eyes, wheezing or skin irritation in those sensitive to them. These annoying growths affect people with asthma, allergies and other breathing challenges. It's easy to detect both mold and mildew. The decomposition of organic material caused by the growth of mold creates a "musty" smell. The only effective way to control mold is to control moisture. A dry basement is free of mold and mildew.
Effects of Mold
Excessive exposure to some types of mold can cause or worsen conditions such as asthma, hay fever, and other allergies. Depending on the amount of exposure, more serious health effects such as fevers and breathing problems can occur.
Prevent Mold Growth
The only effective way to control mold is to control moisture. Mold resistant material is effective only when used in conjunction with proper moisture control.
Undetected leaks can create an environment for mold to grow.
What you can't see...
Basements with any degree
of humidity or water are responsible for an unpleasant odor thatsometimes proves to be ahealth hazard for anyone with allergies or a sensitive respiratory system. Undetected moisture and water, perhaps behind a basement finished wall, can create an environment for mold and mildew to grow.
You don't need a flood to have major problems in your basement.
The best and most cost effective strategy to managing the growth of mold and mildew is to prevent the intrusion of water.
Radon Gases
Radon is an invisible and odorless radioactive gas and is continuously created by natural breakdown metals in soils.
Radon is a cancer-causing natural radioactive gas that you can't see, smell or taste. Radon is the leading cause of lung cancer among non-smokers and claims about 21,000 lives annually. Radon enters the 
basement environment and circulates to the floors above by air.
Effects of Radon
Radon decaying products causes cancer. It is estimated that 12% of all lung cancers are caused by exposure to Radon gas. It is also estimated that 15,000 to 21,000 of the 158,000 lung cancer deaths per year in the United States are caused by exposure to Radon. Many years may pass before the effects of Radon are detected. The E.P.A reports 26,000 deaths a year related to exposure to Radon Gas in America.
Prevent Radon Gas
Minimize the entry of radon gas into your home by sealing cracks in the foundation and along the basement walls, floors or molding. Cover all crawl spaces with a heavy polyethylene barrier and seal it to the foundation wall. Close sump pump pits and floor drains.
Any home in any state may have a radon problem. The average person receives each year more radiation from radon than from all other sources. Almost all risks come from breathing air with radon and it decayed products.
Stack effect will cause radon inflow that will migrate into the home
Air pressure inside homes (basements) is slightly lower than in the ground, creating a vacuum which draws in radon from several feet away into the basement through openings and pores in concrete. Warm air inside homes moves upward like inside a stack. This stack effect reduces air pressure in the basement. When the ground is soaked with rain, the bottled up radon gas moves to a warm opening, such as a basement.This stack effect will cause radon inflow that will easily migrate into the home.