Which chemical agent is known for causing delayed symptoms up to 48 hours?

Mustard gas is a chemical agent renowned for causing delayed symptoms, often appearing 24 to 48 hours after exposure. This delay in symptoms can lead to a false sense of security for those exposed, as they may feel fine initially but can later experience painful effects such as skin blisters, respiratory issues, and other serious complications. Mustard gas acts as a vesicant, damaging tissue on contact, which contributes to the delayed reaction when internal exposure occurs or when symptoms manifest more slowly.

The other options, such as sarin and VX, are classified as nerve agents, which typically produce symptoms almost immediately upon exposure. Lewisite, although it can cause immediate effects, is not characterized by the significant delay in symptoms like mustard gas is. Understanding the unique properties and timelines of each chemical agent is crucial for effective response and treatment in cases of exposure.