Whether it's from standing water after a rainstorm or just the dirt floor, evaporating moisture can damage wood and insulation and eventually make its way into your home. Mold in the crawl space and upstairs living areas is a common problem caused by excess moisture
Moisture in the crawl space is a magnet for spiders, mice, rats, snakes, termites and other nasty pests. Because the crawl space is usually left undisturbed, this provides a safe haven for critters looking for a cozy home. What's more, much like our kids, critters don't usually clean up after themselves. Pathogens from rodent droppings ad urine can affect the air quality inside your home.
You can't see or smell radon gas, but it's found in almost all soils. It comes from the natural decay of uranium and it moves up through the ground and into the air above and eventually into your home. Studies have linked radon exposure and lung cancer. In fact, radon is the number one cause of lung cancer among non-smokers, according to the Environmental Protection Agency (EPA).
If the air outside is worse than the air inside, then vents into the crawl space will let this polluted outside air into your crawl space and eventually up into your home. The poor air quality can make allergies, asthma and respiratory issues worse.
The Natural airflow in a house is from bottom to top. This sucks the moist air and everything in it up into the living areas of the home. Mold spores, odors, humidity, and critters create a very unhealthy environment for people. Many people are allergic to these things and experience a host of symptoms and don't realize that their dirt crawl space is affecting their health. Dirt crawl spaces do not have to be wet or flooded to be extremely unhealthy.