What Are Photochemically Reactive Products?

Photochemically Reactive Products

• In the very basic sense of the terminology, a photochemically reactive product is one that will undergo a reaction in the presence of light. Chemical reactions take place between the valence electrons of one atom and another. There is a certain amount of energy - called the energy threshold - required to allow the process to take place. Since light is simply a source of energy, it can also contribute to the activation energy. Some examples of these types of chemicals come in the category of organic compounds from emissions.

Environmental Protection Agency

• The EPA has released a report stating that the amount of oxidants in the atmosphere, ozone, is directly related to the amount of photochemically reactive organic compounds, or PROCs, found in the air. Due to this fact, the EPA has decided to attempt to control the amount of PROC released into the air. The smog test that nearly everyone is required to do for state registration is one attempt to do so. One goal of the EPA is to find and decrease the amount of PROCs found in consumer goods.

PROC Release

• The amount of PROCs found in consumer goods is different than the amount actually released into the environment. Some of the chemicals may become physically or chemically bound to a container which will become part of a landfill. Another portion may be released into the water systems, thus preventing it from contributing to the atmospheric oxidants. Also, a small portion may be consumed by microbes found in sewage systems.

Volatile Organic Compounds

• When talking about a photochemically reactive product, it is also useful to mention another class of chemicals to make a distinction between the two. Organic chemicals that are highly volatile are said to be a volatile organic compound. This class differs due to absence of a photochemically reactive component. This means that the chemicals are volatile enough to be found within the atmosphere, but they are not reactive enough to contribute to oxidants in the air. Some examples of this category include acetone, propane, methanol and isopropanol. Methane and ethane do have a small photochemically reactive component but not enough to contribute to atmospheric oxidants.