Is that what they mean by "Earth day"? Probably not. Anyway, it could stimulate your immune system and possibly help prevent allergies. Not that actually consuming some earth is a possible key, but recently there was another report out that exposure to a little dirtiness, and some common microbes, could boost the developing immune system and potentially prevent at least some allergies and autoimmune problems.

Excessive cleanliness is to blame according to Dr. Guy Delespesse, a professor at the Universite de Montreal Faculty of Medicine. Dr. Delespesse thinks that "The more sterile the environment a child lives in, the higher the risk he or she will develop allergies or an immune problem in their lifetime." This has generally become known as the "Hygiene Hypothesis". Although hygiene does reduce our exposure to harmful bacteria it also limits our exposure to beneficial microorganisms. Previously, German researchers at University Childrens Hospital in Munich found that mothers exposed to farms, particularly to barns and farm milk, while pregnant confer protection from allergies on their newborns. The exposure apparently affects the babys T regulatory cells, which act to suppress immune responses and thereby maintain immune system balance. Other studies have suggested that not only too much cleanliness, but also exposure to cleaning products, could have an affect.

The culprit is more likely not exposure to common dirt, but exposure to common microbes. Hygiene is good, and in order to avoid people getting the wrong idea, some have proposed calling this the "microbial exposure hypothesis". The concept is that we need a little exposure to the usual bugs encountered in the environment, to train our immune systems. Researchers at Northwestern University suggested easing up on antibacterial soap and perhaps allowing children to get a little dirty, to acquaint them with everyday germs. They noted that we may be depriving developing immune networks of important environmental input needed to guide their function throughout childhood and into adulthood.

So go get a little dirty, and help your immune system.