The ozone layer completely blocks UV-C rays, the Sun's most dangerous form of radiation.

Ultraviolet radiation is classified by wavelength, with UV-C being the shortest and most energetic at 100 to 280 nanometers. Because of its high energy, UV-C is germicidal and is frequently used in specialized lamps to sterilize surfaces and water by destroying the molecular bonds in DNA. If these rays reached the Earth's surface, they would cause severe biological damage to plants, animals, and humans.The Earth's atmosphere acts as a natural filter through the Chapman Cycle, a process first described by British physicist Sydney Chapman in 1930. In the stratosphere, oxygen molecules (O2) absorb high-energy solar radiation and split into individual oxygen atoms. These atoms then combine with other O2 molecules to form ozone (O3), which is exceptionally efficient at absorbing UV radiation.Specifically, the ozone layer absorbs about 97% to 99% of all medium-frequency UV-B rays and 100% of high-frequency UV-C rays. This absorption occurs primarily at altitudes between 15 and 35 kilometers above the Earth. According to NASA and the World Meteorological Organization, the preservation of this layer is critical, as even a small increase in UV-C penetration would lead to widespread mutations and the collapse of marine ecosystems.International efforts like the 1987 Montreal Protocol have been vital in protecting this shield by phasing out ozone-depleting substances like chlorofluorocarbons. Scientific monitoring continues via satellites and ground-based stations to ensure the ozone layer remains thick enough to block these lethal wavelengths. Without this protective barrier, the intense energy of UV-C would break down organic molecules, effectively sterilizing the planet.