Which statement best describes the impact of smoking on healing?

• A. Smoking impairs healing and increases nonunion risk
• B. Smoking accelerates bone healing
• C. Smoking has no effect
• D. Only affects soft tissues, not bone

Answer: (A)

Smoking impairs healing through several mechanisms that blunt the body's ability to repair bone and soft tissue. Nicotine causes blood vessels to constrict and carbon monoxide reduces oxygen delivery, while other tobacco toxins disrupt the activity of bone-forming cells and the formation of new blood vessels. The result is slower callus formation, weaker tissue repair, and a higher risk of nonunion in fractures. This makes the statement that smoking impairs healing and increases nonunion risk the best description. The other ideas—that smoking accelerates healing, has no effect, or only affects soft tissues—do not fit because smoking also delays bone healing, not just soft tissue, and certainly does not speed up recovery.