Complex sentence: He also confirmed that UVA was responsible for skin aging, skin cancer, unwanted pigmentation and skin sagging and during this research period he also proved the protectiveness of sunscreens against UVA damage in human studies.
Split into simpler sentences: He also confirmed that UVA was responsible for skin aging, skin cancer, pigmentation and skin laxity. During this research period he also proved the protectiveness of sunscreens against UVA damage in human studies.