The immune system is the body's defense against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade body systems and cause disease.
When the humidity is high it feels oppressive outside because sweat doesn't evaporate and provide cooling. When the humidity is low you feel cooler, but your skin dries out and you get dehydrated more easily because more moisture is being evaporated from your body. The same thing applies to crops in high and low humidity. A high water vapor content is necessary to produce clouds and precipitation.
Controlling the humidity in your home is critical to staying comfortable and avoiding problems with your home. For example, too much home humidity -- which is common during summer -- can cause allergies and promote the growth of mold, which can be a health risk and cause structural damage in your home.