Children who are raised on a farm have a significantly reduced risk of asthma, eczema, and hayfever, according to a study in the October 6, 2001 issue of The Lancet. Non-farm children who were exposed to stables during their first year also showed this protective effect, with the degree of protection depending on the duration of exposure both during and after the first year, up until 5 years old. All of these conditions are over-exuberant responses to substances in the environment. Both too much and too little immune response is unhealthy. Experiences in early childhood can teach the body to set the level of immune protection 'just right'.