Pressure Points
What does global warming
potential mean for the
aerosol industry?
10 Spray September 2019
NICHOLAS GEORGES
HCPA Senior Director
Scientific & International Affairs
ngeorges@thehcpa.org
There is little doubt among scientists about the impact
of human activity on the Earth’s climate1. The levels of
greenhouse gases (GHGs) in our atmosphere are higher
now than in the last 650,000 years (or longer2). Carbon dioxide,
methane and nitrous oxide are all naturally occurring GHGs, all
of which are at their highest levels since the Industrial Revolution3.
Because of the GHGs resulting from human activity, the
Intergovernmental Panel on Climate Change (IPCC) estimates
that the global average surface temperature has increased 0.85°C
between 1880 and 20124.
Global Warming Potential (GWP) was developed to compare
the global warming impact of different gases. GWP is a measure
of how much energy the emissions of one ton of a chemical will
absorb over a period of time, relative to one ton of carbon dioxide5.
Thus, the higher the GWP number, the more the chemical
will warm the Earth compared to carbon dioxide.
So why does this matter to the aerosol industry?
In the 1990s, aerosol companies began to use hydrofluorocarbons
(HFCs) as one of the replacement propellant options for
ozone-depleting substances. HFCs are a great tool for formulators
because they are liquified propellants, but do not count toward
volatile organic compound (VOC) limits for consumer products.
While HFCs were one of several very effective propellant options
in addressing ozone-depletion for aerosol products, unfortunately,
many also have high GWP values.
The Montreal Protocol, an international treaty designed to
phase out ozone-depleting chemicals8, is hailed as one of the best
examples of international cooperation. The Montreal Protocol
has had widespread adoption and the hole in the ozone is slowly
healing.
In 2016, the last revision to the Montreal Protocol, known as
the Kigali Amendment, led countries around world to agree to
phase down the production and use of HFCs. Moving toward
lower GWP propellant options has now become a necessity.
While the U.S. has not ratified the Kigali Amendment,
75 countries9 have done so to date and it is up to each
how they choose to phase down their use of HFCs.
In the U.S., the Environmental Protection Agency
(EPA) was working on restricting the use of certain
HFCs before the Kigali Amendment was finalized;
however, those attempts were struck down in the
courts10. You can read more about the D.C. Circuit
Court’s rulings on the EPA Significant New Alternatives
Policy (SNAP) Rules 20 and 21 in the National
Law Review.
The major effect of these rules on aerosols would
have been to restrict the use of HFC-134a except for
limited critical uses, such as propellants in metered
dose inhalers, cleaning products for removal of grease,
flux and other soils from electrical equipment or
electronics, or pesticides for use near electrical wires
or in aircraft. HFC-134a has similar restrictions and
exemptions in Canada for use as an aerosol propellant;
however, a few key uses, such as duster sprays
for energized electrical equipment, are not allowed
in Canada unless the manufacturer obtains a permit.
In addition to product-specific restrictions, Canada
also has a phase down of all HFCs, including HFC-
152a. The use of HFCs with a GWP greater than 150
became prohibited on Jan. 1, 2019, with the exemption
of several critical uses.
While the EPA works to fill the void left by the
Court’s decisions and come out with a new federal
proposal, States have stepped in to restrict the use of
HFCs. To date, California, Washington and Vermont
have passed legislation to prohibit the use of HFCs
listed in Appendix U and V of Subpart G of the 40
CFR Part 82 (as read on Jan. 3, 2017).
Global Warming Potential Values
Chemical Common Name Chemical Formula Lifetime GWP Over
(years) 100 Years
Methane CH4 12.44 284
Nitrous Oxide N2O 1214 2654
Propane C3H8 0.036 3.3
Butane C4H10 0.0196 47
Dimethyl Ether CH3OCH3 0.0157 17
CFC-11 CCl3F 454 4,6604
CFC-12 CCl2F2 1004 10,2004
CFC-113 CCl2FCClF2 854 5,8204
CFC-114 CClF2CClF2 1904 8,5904
HCFC-22 CHClF2 11.94 1,7604
HCFC-141b CH3CCl2F 9.24 7824
HCFC-142b CH3CClF2 17.24 1,9804
HCFC-225ca CHCl2CF2CF3 1.94 1274
HCFC-225cb CHClFCF2CClF2 5.94 5254
HFC-125 CHF2CF3 28.24 3,1704
HFC-134a CH2FCF3 13.44 1,3004
HFC-152a CH3CHF2 1.54 1384
HFC-227ea CF3CHFCF3 38.94 3,3504
HFC-365mfc CH3CF2CH2CF3 8.74 8044
HFC-43-10-mee CF3CHFCHFCF2CF3 16.14 1,6504
HFO-1234ze CF3CH=CHF 0.0454 < 14
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