The medical profession divides the ultraviolet region of the electromagnetic spectrum into three bands: UVA (320 nm–420 nm), UVB (290 nm–320 nm), and UVC (100 nm–290 nm). UVA and UVB promote skin cancer and premature skin aging; UVB also causes sunburn, but helpfully fosters production of vitamin D. Ozone in Earth’s atmosphere blocks most of the more dangerous UVC. Find the frequency range associated with UVB radiation.