Linda,
Good question. Basically, what the intent here is to have understanding of the environment that the product will be used in, and having the understanding of applying those environmental conditions, and their impact on the product, into your design activities. In the case of our product, (returnable packaging), we need to understand the environment of use. (assembly plants, high impact conveyor lines etc)
We take that info into consideration when we design; using heavier materials etc. to increase the durability and reliability of the product.
Hope this helps
Bryon