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Also known as: Chlorofluorocarbons, CFCs, Halons. Other names include: Fluorotrichloromethane, Dichlorodifluoromethane, Trichlorotrifluoroethane, Bromochlorodifluoromethane, Dibromotetrafluoroethane, Chlorodifluoromethane.

Freons are colorless liquids or gases. Freons were used as coolants or pressurizers in spray can products, including drugs. In the 1970's, scientists discovered that these chemicals were destroying the earth's ozone layer. This was allowing potentially dangerous levels of ultraviolet light to reach the earth. The making and use of freons is now restricted, and freons are being replaced by safer chemicals.

Freons are gases at normal room temperature, liquids when cooled or compressed. Spilled liquid freons do not remain at the spill site for more than a few minutes before they evaporate. If liquid freons leak into soil before evaporation, they can seep into groundwater.

Breathing gases from spray products is the way most people are exposed to freons. People can also breathe freons that have leaked from refrigerators or air conditioners. It is possible for people to breathe freons from contaminated water; however, freons are not usually found in drinking water. Freons may occasionally contaminate groundwater near industrial plants, and people may drink this water. Plants do not take up freons when they are grown in contaminated soil.

When people touch liquid freon, the chemical evaporates before it has a chance to pass through the skin. Some freons evaporate so fast that they can cause frostbite.

No standards exist for regulating the amount of freons allowed in the air of homes. However, the Wisconsin Department of Natural Resources (DNR) has set a residential indoor air action level for:

  • dichlorodifluoromethane (Freon 12) at 20 parts per billion by volume (ppbv)
  • trichlorofluoromethane (Freon 11) at 130 ppbv

The action level is considered to be protective of public health. Breathing these freons at these concentrations for a lifetime is very unlikely to be harmful to people. If dichlorodifluoromethane or trichlorofluoromethane concentrations in air are above their respective action levels, we recommend taking action to halt exposure.

The Federal Clean Air Act Amendments of 1990 specify the concentrations of freons that can be released into outdoor ambient air by industries.

There are no federal drinking water standards for any of the freons. However, there are state groundwater standards for:

  • fluorotrichloromethane (Freon 11) at 3,490 parts per billion (ppb)
  • dichlorodifluoromethane (Freon 12) at 1,000 ppb.

We suggest you stop drinking water that contains more than these levels of these freons.

Everyone's Reaction is Different

A person's reaction to chemicals depends on several things, including individual health, heredity, previous exposure to chemicals including medicines, and personal habits such as smoking or drinking. It’s also important to consider the length of exposure to the chemical, the amount of chemical exposure, and whether the chemical was inhaled, touched, or eaten.

The following health effects may occur immediately or shortly after people are exposed to elevated levels of freons:

  • Irritation to mouth, throat, lungs, and nose following inhalation of freons
  • Heart palpitations and dizziness after inhalation of gases
  • Freezing of skin and possible frostbite following skin contact with liquid freons

Years of exposure to freons are not likely to increase a person's risk of getting cancer.


No medical tests are available to determine freon exposure. Medical tests of lungs, skin, and nervous systems can help doctors determine the extent of damage caused by high level exposure to freons. Seek medical advice if you have any symptoms that you think may be related to chemical exposure.

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Last revised June 15, 2022