Historically, concrete shelters have been used to protect people from nuclear blasts. Comment on the effectiveness of such shelters.

Step by Step Solution: Step 1. Concrete is a durable and sturdy material, and can provide substantial protection against the blast wave, heat, and radiation that are the most common post-nuclear effects. Step 2. However, the effectiveness of a concrete shelter will depend on various factors such as the proximity of the explosion, the size of the blast, and the strength of the shelter itself. Step 3. In general, a well-built concrete shelter can provide a high degree of safety for people inside. But no shelter can offer complete protection from a direct hit or a powerful nuclear explosion. Final Answer: Concrete shelters can provide a high degree of safety from nuclear blasts, but their actual effectiveness depends on multiple factors.