History of the Aerosol
The first use for an aerosol package arose during World War II, but the idea of using low-pressure liquefied gas to atomize droplets of liquid in the air was developed in 1924. Canisters filled with insecticide and propellants were used to protect U.S. servicemen from insects carrying diseases such as malaria. Shortly after the war, Robert Abplanalp, founder of Precision Valve Corporation (PVC), invented the first mass-produced aerosol valve. The patent was filed in September 1949 and was issued on March 17, 1953. From that invention, the aerosol industry quickly developed in the United States and around the world.
How an Aerosol Works
The aerosol package is a self-contained dispensing system with
three main elements:
-
Active Ingredients (soap or disinfectant, etc.)
-
Inert or Inactive ingredients (water)
-
Propellant
The propellant is a gaseous compound which pushes the product
out of the container and produces a spray or foam. In most cases, the propellant
also acts as a solvent to keep the product at the proper strength. In the United
States, the most common propellants are naturally occurring hydrocarbons. A few
products, about 10% of today’s aerosols, use compressed gases like carbon
dioxide and nitrous oxide as propellants.
The final element is the container, which is usually a steel or
aluminum can. The leak-proof can protects the product from contamination and
evaporation.
All of these pieces work together based on simple scientific
principles. An aerosol package is an air-tight, pressurized container. Pressing
the actuator button opens the valve. Since the pressure outside the can is less
that the pressure inside, the propellant expands, pushing the product up the dip
tube and out through the valve. This system allows the product to be applied in
a variety of ways; in a fine mist, a metered spray delivering just the right
amount, foam, or even a long distance spray.
Let’s Set the Record Straight on Aerosols!
Q. What are
aerosols, anyway?
A. Aerosols are
very fine particles of liquid or solid substances suspended in air. Fog, for
example, is a normal aerosol. In aerosol packaging, the substance to be sprayed
is propelled through a valve as a fine mist or foam. This provides a safe,
efficient means of dispensing thousands of consumer products such as shaving
cream, hair spray, paint and antiperspirants.
Q. How long have
aerosols been around?
A. Sixty-five
years ago, U.S. Department of Agriculture scientists developed the principle of
pressurized insect spray. This gave birth to the container used by American
troops to fight malaria by killing mosquitoes in the South Pacific during World
War II. Today’s lightweight low-pressure can is a direct descendant of those
ponderous, high-pressure canisters. Refinements to containers, valves,
propellants and formulas have broadened the range of aerosol products and
widened consumer acceptance. Aerosol-related jobs now employ over 50,000
Americans.
Q. What is the
ozone layer?
A. In the
stratosphere, some 12-20 miles above the Earth, ozone (an unstable and very
reactive form of oxygen) forms a protective layer that blocks most of the sun’s
ultra-violet rays.
Q. What causes
ozone depletion?
A. In addition to
natural phenomena such as earthquakes, among the man-made products believed to
contribute to ozone damage are chlorofluorocarbons (CFCs) used mainly in
refrigerators and air conditioners. CFCs contain chlorine which attacks ozone in
the upper atmosphere.
Q. Do aerosols
contain chlorofluorocarbons?
A. Since 1978, no
aerosols made or sold in the U.S. have contained CFCs except for a tiny fraction
(less than 2%) specifically approved by the government for essential medical and
other unique uses, such as inhalers for asthma sufferers. Not only are CFCs
absent from the propellant used in aerosols, but there are no CFCs in the
products packed in aerosol packages, such as hair spray, deodorants,
antiperspirants or other personal care items, nor are they in spray paint,
household, food or automotive products. The industry is in full compliance with
rules established by the EPA, the FDA, and the Consumer Products Safety
Commission.
Q. Then why the
confusion?
A. Aerosol
manufacturers in Europe and other parts of the world initially did not follow
the lead of the U.S. industry in substituting alternative propellants for CFCs.
The fact that aerosols made in underdeveloped countries may contain CFCs has
caused confusion in press reports and in the public mind about the stratospheric
ozone/aerosol link. However, American consumers can be confident that aerosols
made in the U.S. will not damage the ozone layer. Other countries have also
changed from ozone-depleting propellants to non-depleting forms because those
countries signed the Montreal Protocol. The Montreal Protocol, of which the
U.S.A. was a signatory, may arguably be the most effective international
environmental agreement ever written. All nations of the world signed the
agreement and the phase-out of CFCs and ozone-depleting substances (ODS) is 90%
complete worldwide.
Q. What about the
problem with urban smog, also known as ambient ozone?
A. As urban areas
struggle to meet federal air quality standards, regulators are attempting to
identify any products that emit volatile organic compounds (VOCs) which in turn
contribute to lower level ozone. Unlike upper level ozone, which protects us,
this lower level or tropospheric ozone is a major component of smog. The smog
problem is particularly acute in California and that state has identified a
variety of consumer products which emit VOCs as among those sources and are now
being regulated.
Q. So aerosols do
contain VOCs?
A. Yes, but so do
fingernail polish, perfume and mouthwash, as well as pump hair sprays, roll-ons,
and stick deodorants. Restrictions on these products are hardly the answer to
air pollution. The solution to the smog problem, for example, lies on the
freeways and in the power plants…not in the medicine cabinet or the bedroom!
Q. What
propellants are used in aerosol containers today?
A. Depending on
the end use, either liquefied or compresses gases are used to dispense the
product from the aerosol container in the most efficient manner. Neither type is
a chlorofluorocarbon. Liquefied propellants, such as isobutene, normal butane or
pentane, are natural organic products which do not deplete the ozone layer,
taint the soil or pollute the water supply. They do not contribute to global
warming. As used in aerosol cans, their contribution to lower level ozone
formation is negligible.
Compressed gas, such as carbon dioxide (the same gas which puts
the “fizz” in soda pop) is used in products designed to deliver a coarse spray
at close range…in household disinfectants, or example. Nitrogen, as used in
contact lens cleaners and nitrous oxide, as used in whipped toppings, are also
used as propellants.
Q. If the
contribution of aerosols to air pollution is minimal, then why are they suspect?
A. Aerosols, still
remembered from the pre-1978 chlorofluorocarbon/ozone controversy, offer a
convenient target. Perhaps because of their “high tech” characteristics, they
don’t seem to fit the profile of a “natural” product. Rather than switching to
non-aerosol containers, well-meaning consumers who are concerned about air
quality would be far better advised to simply maintain the family car properly!
Q. But aren’t
alternative packages better for the environment?
A. Once again,
myth prevails over reality. For example, pump sprays are generally perceived as
being environmentally superior. Actually, the ingredients in the pump container
which replace the aerosol propellant, contain many more reactive VOCs than the
aerosol package. The aerosol steel can is fully recyclable; pumps and roll-ons
are not.
Q. But after all,
do we really need aerosols?
A. The aerosol
container is a unique package. It is convenient, effective and efficient. It
offers consumers a controlled “clean hands’ way to deliver personal care, spray
paint, household and automotive products. It is hermetically sealed and its
contents are always free of bacterial contamination.
It would be tragic indeed if aerosols were to be replaced with
less effective alternatives, with absolutely no resulting improvement in air
quality. Evidently the American consumer agrees, in that 3.7 billion aerosol
units were produced in the USA in 2005. Western Europe, which also does not use
CFCs as propellant, produced over 5 billion aerosol units in 2005.
Safety and Disposal
Like most household or personal care products, aerosols are not
hazardous when handled and disposed of properly. Reading and following the
instructions printed on the label will ensure proper and safe use. The label
instructions are there for your protection.
The best way to dispose of an empty aerosol container is to
recycle it. Aerosol cans are made of steel and aluminum and can be recycled like
any other empty steel cans. A growing number of communities accept empty aerosol
cans together with other metal containers. Check with your local recycling
coordinator, however, before putting any material in your recycling bin. Be sure
the can is empty before placing the container in the trash with your other solid
waste if recycling is not available.
