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Chemical to deice aircraft
In ground deicing of aircraft, aircraft deicing fluid (ADF), aircraft deicer and anti icer fluid (ADAF) or aircraft anti icing fluid (AAF) are commonly used for both commercial and general aviation. Environmental concerns include increased salinity of groundwater where de icing fluids are discharged into soil, and toxicity to humans and other mammals.

The main component of deicing fluid is a freezing point depressant (FPD), usually propylene glycol or ethylene glycol. Other ingredients vary depending on the manufacturer, but the exact composition of a particular brand of fluid is generally held as confidential proprietary information. Ethylene glycol (EG) fluids are still in use for aircraft deicing in some parts of the world because it has a lower operational use temperature (LOUT) than propylene glycol (PG). However, PG is more common because it is less toxic than ethylene glycol. TKS fluid (used by TKS in flight deicing systems) contains 85% ethylene glycol, 5% isopropyl alcohol, and 10% water.

The amount of fluid necessary to deice an aircraft depends on a wide variety of factors. Deicing a large commercial aircraft typically consumes between and of diluted fluid. The cost of fluid varies widely due to market conditions. The amount deicing service companies charge end users is generally in the range of US$8 to US$12 per diluted gallon (US$2.10 to US$3.20 per liter). The total annual usage of deicing fluids in the U. S. is estimated to be approximately , broken down as follows (figures from 2008, adjusted to show totals for undiluted fluid):

For Type I fluids, the Holdover Time listed in the FAA tables ranges from 1 to 22 minutes, depending on the above mentioned situational factors. For Type IV fluids the Holdover Time ranges from 9 minutes to 160 minutes.

Deicing fluids work best when they are diluted with water. For example, undiluted Dow UCAR Deicing Fluid (Type I ethylene glycol), has a freezing point of −28 °C. Water freezes at 0 °C. However, a mixture of 70 percent deicing fluid and 30 percent water freezes below −55 °C. This is known as the eutectic concentration, where the freezing point of the mixture is at its lowest point, and lower than either of the component substances. Depending on the manufacturer, deicing fluids may be sold in concentrated or pre diluted formulations. Dilution, where necessary, must be done according to ambient weather condition and the manufacturer's instructions in order to minimize costs while maintaining safety. The dilution of a particular sample of fluid (and hence its freezing point) can be easily confirmed by measuring its refractive index with a refractometer, and looking up the result in the deicing fluid manufacturer's tables.

Manufacturers of aviation deicing fluids must certify that their products conform to the AMS 1424 and 1428 standards using the defined High Speed Ramp Test, Low Speed Ramp Test, and Water Spray Endurance Test. The objective of these standards is to ensure acceptable aerodynamic characteristics of the deicing/anti icing fluids as they flow off aircraft lifting and control surfaces during the takeoff ground acceleration and climb. With the development of non glycol deicing fluids these standards are evolving to address additional factors such as corrosion, foaming, thickening, residue formation, slipperiness, and mold formation.

Many de icing fluids, including glycol based fluids, are toxic to humans and other mammals, and damage the ecosystems where the fluids are discharged, such as the areas around airports. The use of such fluids can cause changes to nearby acquatic habitats that harm fish and other wildlife. Ethylene glycol and propylene glycol exert high levels of biochemical oxygen demand (BOD) during degradation in surface waters. Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol. This process can adversely affect fish and other aquatic life by consuming oxygen needed for their survival. Thickened fluids typically use alkylphenol ethoxylate (APE) surfactants, the biodegradation products of which have been shown to be endocrine disruptors, and as such these are banned in Europe and are under EPA scrutiny in the U. S. A number of fluids also use benzotriazole or tolyltriazole corrosion inhibitors, which are toxic and non biodegradable and thus persist in the environment. Research is ongoing to find less problematic alternatives. This is proving to be challenging due to the many performance and safety factors that need to be considered. One U. S. FAA approved deicing fluid (Kilfrost DF Sustain) is 1,3 propanediol, a fermentation product of corn, as a freezing point depressant instead of ethylene glycol or propylene glycol. Benzotriazole (and tolyltriazoles), although not highly toxic, is not readily degradable and has a limited sorption tendency. Hence, it is only partly removed in wastewater treatment plants and a substantial fraction reaches surface water such as rivers and lakes.