CFCs and other substances contributing to this effect are referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (280–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern. As a result, the Montreal Protocol has been adopted. The treaty bans the production of CFCs, halons as and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane. The biological consequences of this change in ozone levels may include an increases in skin cancer, cataracts, damage to plants, and the reduction of plankton populations in the ocean.