Dear Umbra,
Love the column. Keep up the great stuff! A question: My co-workers and I are suspicious of buying spray cans, even though we know they no longer contain CFCs. We suspect that aerosol cans contain HCFCs -- hydrochlorofluorocarbons -- which are proving to be dangerous as well, this time as greenhouse gases. Do all aerosol cans contain HCFCs? Can we trust a "green" product like an essential-oils-and-water-based deodorizer that comes in an aerosol can? And what about non-aerosol cans -- are their contents safe?
Kate
Boulder, Colo.
Dearest Kate,
Thank you for the compliments. In grateful return, I will tell you all I've learned about the aerosol can. An aerosol is a wee particle or liquid droplet that's suspended in air, including natural forms seen in smoke, dust storms, or sea spray from the briny deep. Naturally occurring aerosols are of great interest to climate scientists, as (of course) are the propellants that shoot products out of aerosol cans. In former days, the go-to propellants were CFCs, or chlorofluorocarbons.
Put the can down and back away.
A can creates aerosols much the same way we might transform drool into a fine spray, if we weren't so gosh-darned busy. If we simply open our mouths and let saliva fall out, we get a goopy liquid (thus, the bib industry). If, on the other hand, we apply pressure and narrow our lips, we can push the liquid out of a smaller hole, and it becomes an aerosol. Aerosol cans follow a similar principle, if a bit more explosively. A liquid product is poured into a can, the can is closed, and gas propellant is pumped in under high pressure. The gas, crowded and uncomfortable, presses hard on top of the liquid. When we press the nozzle, a tiny seal opens inside the bottle and the gas pushes the product out of a too-small hole, rendering it misty or foamy. Then we shave.
The propellants known as CFCs, widely embraced for being non-toxic and non-flammable, were hugely popular until the 1970s, when scientists realized that they broke down in the upper atmosphere and released chlorine. Chlorine, they found, is a "catalytic agent" in ozone destruction, allowing too much ultraviolet light to hit us. An international agreement to phase out CFCs was forged in 1987 and, as of this December, the U.S. ban on ozone-depleting CFCs will be complete.
Unfortunately, manufacturers have used CFC replacements that have problems of their own. HCFCs were substituted for CFCs in many instances, but, though less harmful, they also contain ozone-depleting chlorine. In this country, HCFCs are being phased out and will be completely banned by 2030. I should mention here that there are eye-glazing varieties of all these chemicals, which are used in many assorted ways (not just in aerosol cans) and were banned in different years. For example, according to the U.S. EPA (where no one, apparently, is regulating acronym use) the compound HCFC-141b has the highest ODP, or "ozone depleting potential" -- the quantification of badness -- of any HCFC, and the U.S. can no longer produce or import it. The EPA offers lists of "acceptable substitutes" that have little or no ODP, which presumably will allow the aerosol industry to continue its fine spraying into the future.
The ozone hole has very little to do with global warming but, as Kate mentions, some of the newer propellants are potent greenhouse gases that have high "global warming potential." These gases, including hydrofluorocarbons, are far more heat-trapping than CO2, though less abundant. (As you know, greenhouse gases are not regulated in the U.S.) Additionally, the volatile organic compounds found in many propellants are now targets for fussy state governments concerned about clean air.
Unfortunately, I could find no perfect list of which propellant is used by which aerosol can vendor. But I think it's safe to say that, although aerosol cans make a satisfying noise and well-fluffed shaving cream, it's usually best if we don't use them.
Even non-aerosol sprays, which spit lightly upon us via a pump and nozzle, may contain volatile or non-earth-friendly substances. Still, I don't believe that any volatilizing ingredient in a simple spritz-y deodorizer bottle could compete with aerosol propellants on the environmental-destruction front. Famous last words? I hope not.
Propellantly,
Umbra
Cobbling together a delicious and easy summer dessert
Ask Umbra on paperback writers
Comments View as Flat
Phil Hanson Posted 6:07 am
06 Oct 2008
Aerosol Propellants
Forgive my ignorance, but is there any reason why plain ol' compressed air can't be used as a propellant? I mean, other than the fact that it's not nearly as destructive of the environment as CFCs and HCFCs.
Permalink
2wheeler Posted 12:35 am
07 Oct 2008
Spray Cans using only Compressed air
For over 10 years it has been possible to buy refillable, "rechargeable" aerosol spray cans that are powered by good old compressed air. These would be popular with those who wish to save money by buying the sprayable products in bulk liquid form.
These items retail for something on the order of 10 bucks and up, which is reasonable for the large scale commercial user who might otherwise consume several cans of a single product each week or month. They represent an opportunity for waste reduction at several levels. just search for "refillable aerosol" and you'll find them, I've also seen them in local a local cheap imported tools store.
Permalink
redambrosia99 Posted 4:00 am
07 Oct 2008
tiny particles
Also consider that anything in it's aerosol state is very dangerous to your lungs. The most healthy things can become deadly toxins once they become so tiny. They get in your lungs and just rip them to shreds. So always be sure to wear a good face mask and eye protection when dealing with anything that's been aerosol'd.
Permalink
rdimont Posted 4:00 am
08 Oct 2008
Aerosol Cans
Aerosol cans can also have CO2 and propane as a propellant. The real problem outside the ozone depleting chemcials is that the product inside the can comes out as a respirable particle that can go deep down into your lungs. That's what makes hairspray just about as deadly a product as you can use; people often use it in a confined space, such as a bathroom, and too close to their breathing zone, net result-lung cancer, emphysema, or other chronic repiratory problems.
Permalink
verkwon Posted 12:01 pm
08 Oct 2008
why aerosols anyway?
this simply goes back to the first R, reduce. what is there that you really need that it aerosolized? deodorants? hardly. essential oils? these also come in small vials for using in oil candles etc. it's not that hard. Reduce.
Permalink
dougfratz Posted 4:08 am
15 Oct 2008
Errors in Aerosol Products Answer
Grist is a fine website with much useful information. However, Umbra Fisk's response to this question about aerosol products contains several errors. First, companies producing aerosol products in the United States stopped using CFCs in 1978. This was the first phase-out of any CFC uses anywhere. Other uses for CFCs, such as for refrigerants, also now have been phased out in the US and most of the world. Second, U.S. aerosol products did not move to HCFC propellants (as was done for refrigeration and air conditioning), but went directly to use of hydrocarbons (natural gas) and compressed gases (nitrogen, carbon dioxide, etc.). These aerosol propellants have minimal global warming potential (GWP) because both carbon dioxide and nitrogen are obtained from the atmosphere. Also, while it is true that HFC propellants used in a small number of aerosols contribute to GWP, HFC use is very small and is primarily limited to HFC-152a--the lowest GWP of all HFCs. The aerosol products industry has worked hard for more than 30 years to assure that aerosol products are environmentally compatible. I would be glad to provide any further information you need on today's aerosol products.
-D. Douglas Fratz
Vice President, Scientific & Technical Affairs
Aerosol Products Division Staff Executive
Consumer Specialty Products Association, Inc.
900 17th Street, N.W., Suite 300
Washington, DC 20006
Phone: 202-833-7304
dfratz@cspa.org
www.cspa.org
Permalink
dougfratz Posted 4:31 am
15 Oct 2008
Putting the Air in Aerosols
Aerosol products mostly can't use air as a propellant because air is 20% oxygen, which reacts slowly with other ingredients. Many aerosols do use compressed gases, though, mostly nitrogen (which is most of the other 80% of air)or carbon dioxide.
Permalink
dougfratz Posted 4:36 am
15 Oct 2008
Refillable "Aerosols"
I think what you are referring to are relatively large containers that allow liquids to be sprayed with air pressure. These work fine for many commercial or manufacturing operations that have high usage. They are not the same as the small, recyclable, long-shelf-life products usually thought of as consumer aerosol products.
Permalink
dougfratz Posted 4:45 am
15 Oct 2008
Particle Toxicity
Inhalation of solid or low-volatility-liquid particles between about 1-10 microns can indeed present risks, although it does depend a lot on the chemistry (and sometimes even shape) of the particle. These particles are generally referred to as "repirable" because they are small enough that they can travel deeply into the lungs, but not small enough to get re-exhaled. Aerosol products are very carefully designed to minimize respirable particles that could cause respiratory toxicity. Mostly the particles are 100-1000 microns. There are millions of valve variations that are used to provide the exact right particle sizes.
Permalink