Which radiation produces an erythema which subsides in 2 days?

• A. Infrared radiation
• B. Minimal erythema
• C. Second-degree erythema
• D. Ultraviolet radiation

Answer: (C)

A redness from radiation heals along a spectrum that mirrors how strong the skin’s injury is. When the reaction is mild, you get a light reddening that typically fades within about a day or two. A more pronounced reddening—a moderate erythema—takes longer to settle, often around two days, which fits the description of second-degree erythema. Infrared mainly causes warmth with less defined, short-lived redness, and ultraviolet radiation is the usual trigger for sunburn-type reddening but can vary in duration depending on dose. So, describing a redness that subsides in about two days aligns with a moderate, second-degree erythema rather than a milder or deeper reaction.