PFASs have a wide range of different physical and chemical properties. They can be gases, liquids, or solid high-molecular weight polymers. Some PFASs are described as long-chain or short-chain molecules, but this does not cover all of the different structures in the PFAS class. PFASs can also be sub-grouped in other ways based on their structure. 

PFASs are widely used as they have unique desirable properties. For instance, they are stable under intense heat. Many of them also have surfactant properties and function, e.g. as water and grease repellents.

Some of the major industry sectors using PFASs include aerospace and defence, automotive, aviation, food contact materials, textiles, leather and apparel, construction and household products, electronics, fire-fighting, food processing, and medical articles.

Over the past decades, global manufacturers have started to substitute long-chain PFASs with other PFASs or with fluorine-free substances. This trend has been driven by the fact that the harmful effects of long-chain PFAS on human health and the environment were the first that were recognised by scientists and governments around the globe. As the focus shifted to other PFASs these were also found to have properties of concern.

All PFASs are highly persistent in the environment. In fact, they are known to persist in the environment longer than any other man-made substance. As a consequence of this persistence, as long as PFASs continue to be released to the environment, humans and other species will be exposed to ever greater concentrations of PFASs. Even if all releases of PFASs would cease tomorrow, they would continue to be present in the environment, and humans, for generations to come.

Their release and mobility in water and air causes contamination to groundwater and drinking water, which is difficult and costly to avoid. Certain PFASs are known to accumulate in living things and cause toxic effects. Certain PFASs are toxic for reproduction and can harm the development of foetuses. Several PFASs may cause cancer in humans. Some PFASs are also suspected of interfering with the human endocrine (hormonal) system. 

PFASs are released into the environment from direct and indirect sources, for example, from professional and industrial facilities using PFASs, during use of consumer products (e.g. cosmetics, ski waxes or clothing) and from food contact materials. Humans can be exposed to them every day at home, in their workplace and through the environment, for example, from the food they eat and drinking water.