The plane is being deiced prior to take off, you smell a somewhat sweet odor, and then the pilot makes an announcement that the odor from the deicing chemical is nothing to worry about. Really? What is that deicing chemical being sprayed on the plane? Is it really OK to breathe in those vapors for a few minutes? Here’s a breakdown of the health, environmental, and hazards of deicing chemicals.
There are two main types of aircraft deicing chemicals – orange deicing and green deicing/anti-icing. The orange deicer is the most common. It is used to remove ice from the aircraft. The green one is deicing and anti-icing. It is applied to prevent more ice build up prior to and during take off. The orange chemical most often contains propylene glycol and the green anti-icing contains ethylene glycol.
Orange – Type I Aircraft Deicing Chemical
The Type I deicing chemical is a heated mixture of propylene glycol and water. It can range from a 50/50 mix of propylene glycol/water up to an 88/12 mix. The concentration can change due to the weather conditions. Type I is not flammable, corrosive, or reactive. It is not considered a hazardous chemical according to Occupation Safety Health Administration (OSHA) or a hazardous material by the Department of Transportation (DOT). It is not an EPA hazardous waste when disposed in its original state. It’s not regulated under the Toxic Substance Control Act (TSCA) or CERCLA (aka Superfund). It is biodegradable.
Reading the above paragraph makes it sound not too bad. And it’s not. Although it’s not regulated as hazardous, it is mildly toxic. But in the realm of chemicals that are hazardous to us, it’s mild.
Exposure to the propylene glycol mixture can cause slight irritation of the skin, eyes, or upper respiratory. Ingesting a large amount of it can lead to central nervous system depression. If you get some on your skin or in your eyes, flush it with plenty of water. If it causes you respiratory irritation, move to where you can breathe fresh air.
Green – Type IV Aircraft Deicing / Anti-Icing
The green anti-icing is meant to stick to the plane longer to prevent ice build up. To make it more potent than the orange deicing, it needs to be a stronger chemical. Therefore, Type IV is often a 50/50 mix of ethylene glycol/water. Ethylene glycol is more toxic than propylene glycol, making the green stuff more toxic than the orange stuff. The green anti-icing can be a mix of propylene glycol. That kind would more be similar to the orange stuff. (It’s more fun to call it green stuff or orange stuff than Type IV anti-icing chemical.)
Similarly to the orange deicing, it’s not flammable, corrosive or reactive. Because of the ethylene glycol, the green anti-icing is a hazardous chemical according to OSHA and it is regulated by the DOT when shipped in bulk. It is a DOT Class 9 Miscellaneous. Ethylene glycol contains chemicals that are known to cause cancer.
The same precautions apply for getting it on your skin, in your eyes, and respiratory exposure. Ingesting ethylene glycol is where you have problems. Do not drink it! Wash your hands before eating after exposure to it. If you ingest ethylene glycol, it rapidly absorbs into your system. It first impacts your central nervous system, then cardiopulmonary, and then renal failure. It can cause acidosis, coma, convulsions, or circulatory collapse. Fun, huh?
There is an interesting antidote if you consume ethylene glycol…80+ proof whiskey. Seriously. Ethanol (drinking alcohol) blocks the formation of glycolic acid from developing in your body. A good reason to carry some Johnnie Walker with you when you’re flying in the winter.
Ethylene glycol is biodegradable. But biodegradable can be a misleading term. Biodegradable doesn’t mean it’s not harmful when it hits the dirt or water. The same toxicity applies in the environment as it does to us. As it biodegrades, it slowly loses its toxicity. Propylene and ethylene glycol have high biochemical oxygen demands when degrading. That means the biodegrading process consumes high levels of oxygen from the water, which can impact aquatic life.
Summary
The orange deicing chemical is only mildly toxic. The green anti-icing chemical is more toxic. But neither is extremely toxic, particularly compared to the vast number of toxins we are exposed to on a regular basis.
Think about when you pump gasoline into your vehicle. You may inadvertently breathe in some gasoline vapors when filling up. Gasoline is significantly more toxic than ethylene glycol. Those few minutes of exposure to gasoline vapors are more harmful to you than the few moments of breathing in that sweet orange smell. And it’s likely that you get gas more often than you are sitting in a plane being deiced.
Are you reading this on a plane right now? Is it being deiced? Pass this on to your fellow passengers to ease or inflame their concerns.
Here are the safety data sheets for a more technical look at these chemicals.