Photodegradation is degradation of a photodegradable molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 caused by the absorption of photons, particularly those wavelengths found in sunlight

Sunlight

Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...

, such as infrared radiation, visible light, and ultraviolet light. However, other forms of electromagnetic radiation

Electromagnetic radiation

Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

 can cause photodegradation. Photodegradation includes photodissociation

Photodissociation

Photodissociation, photolysis, or photodecomposition is a chemical reaction in which a chemical compound is broken down by photons. It is defined as the interaction of one or more photons with one target molecule....

, the breakup of molecules into smaller pieces by photons. It also includes the change of a molecule's shape to make it irreversibly altered, such as the denaturing

Denaturation (biochemistry)

Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...

 of proteins, and the addition of other atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s or molecules. A common photodegradation reaction is oxidation. This type of photodegradation is used by some drinking water

Drinking water

Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...

 and wastewater

Wastewater

Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...

 facilities to destroy pollutants. Photodegradation in the environment is part of the process by which ambergris

Ambergris

Ambergris is a solid, waxy, flammable substance of a dull gray or blackish color produced in the digestive system of and regurgitated or secreted by sperm whales....

 evolves from its fat

Fat

Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...

ty precursor.

The US federal standard for testing plastic for photodegradation is 40 CFR Ch. I (7–1–03 Edition)PART 238

Photo degradation also destroys paintings and other artifacts.

Applications

Six-pack

Six pack rings

Six pack rings or six pack yokes are a set of connected plastic rings that are used in multi-packs of beverage, particularly six packs of beverage cans.-History:...

 soda can rings have been photodegradable LDPE plastic since the 1990s.