UV-A is generally non-ionizing, but that doesn’t mean it can’t cause electronic transitions that lead to chemical reactions. https://en.wikipedia.org/wiki/Molec

UV-A is generally non-ionizing, but that doesn’t mean it can’t cause electronic transitions that lead to chemical reactions. https://en.wikipedia.org/wiki/Molecular_electronic_transition https://en.wikipedia.org/wiki/Molecular_electronic_transitio... UV-A can create Thymine diners in your DNA, for example. No ionization required. https://en.m.wikipedia.org/wiki/Pyrimidine_dimer https://en.m.wikipedia.org/wiki/Pyrimidine_dimer