This is not a good idea in any situation because of escaping fumes and dust, and possible contamination. Storage areas are usually built too close to the water supply. Storage areas next to wells are not safe. In a spill situation or explosion, ing liquids can soak into the soil and contaminate the well. The storage area should be at least 50 yards from any well.
Security is a problem with pesticide storage areas.
Measures that will lessen liability problems should be taken. All a vandal would have to do is hit the window with an elbow to gain entrance to the building. Should the intruder be poisoned while in the storage area, a liability problem might occur. If you decide to have a window, put bars over it so nobody can enter through it. The placement of warning signs and locks on the storage area will increase security.