A nurse is reinforcing health teaching about skin cancer with a group of clients. Which of the following risk factors should the nurse identify as the leading cause of non-melanoma skin cancer?

A. Exposure to environmental pollutants is incorrect because, while certain chemicals and pollutants can contribute to skin irritation or cancer risk in specific occupational settings, they are not the primary or leading cause of non-melanoma skin cancers. The majority of cases are not directly linked to general environmental pollution. B. History of viral illness is incorrect because viral infections are not a major cause of non-melanoma skin cancer. Although some viruses are associated with certain cancers, non-melanoma skin cancers such as basal cell carcinoma and squamous cell carcinoma are not primarily driven by viral illness. C. Scars from a severe burn is incorrect because chronic scars and nonhealing wounds can increase the risk of squamous cell carcinoma in localized areas, but this is relatively uncommon and does not represent the leading cause of non-melanoma skin cancer overall. D. Sun exposure is correct because chronic exposure to ultraviolet (UV) radiation, particularly UVB rays from the sun, is the leading cause of non-melanoma skin cancers. Long-term sun exposure damages skin cell DNA, leading to abnormal cell growth and the development of basal cell carcinoma and squamous cell carcinoma. This is why preventive measures such as sunscreen use, protective clothing, and avoidance of peak sun hours are emphasized in patient education.