C4: Critical Cleaning For Contamination Control By: John B. Durkee, Ph.D., P.E. April 2005
The Pact
It was a time when we took a chance for us all. We, the US and 24 other
countries, choose to believe the then-immature atmospheric science, abandon
a highly-sophisticated
and profitable technology, form an agreement called the Montreal Protocol (MP),
and accept the unknown in order to "save the planet."
The MP, about chlorofluorocarbons (CFCs), banned manufacture, not sale—an inspired regulatory choice. With one phrase, the number of firms that had to be "policed" was
reduced from tens of thousands to a dozen or so.
The Technology
The technology was highly-researched molecular structures which were valued
for their inertness. The molecules were CFCs. We valued their inertness,
at least as polymerization solvents, refrigerants, and cleaning agents.
An initial learning for all was "be careful what you wish for." Most
were shocked to learn that the inertness of CFCs allowed them to survive atmospheric
transport from the earth to between 15 and 35 km above the earth's surface
into the stratosphere, and of the continuing damage they could do once there.
The Big Learning
Some of us knew that the invisible ozone layer was beneficial to life on
earth because it absorbs the harmful ultraviolet (UV) radiation from the
sun. Up
to 98% of the sun's high-energy ultraviolet light is consumed in chemical
reactions involving the destruction and formation of atmospheric ozone.
The global exchange between ozone and oxygen is on the order of 300 million
tons
per day.
But precious few of us knew that chlorine radicals produced by the reaction
of CFCs with UV radiation are nearly totally regenerated. So they can destroy
more ozone. They are essentially a catalyst and not a consumed reactant.
That has been the key learning for most of us. That's why we haven't yet
done that which many had hoped to do.
What We Haven't Done, Yet
We haven't filled in the "ozone hole" while converting from CFCs
to something else. Nor have we done so through today. In the United Nations
Environmental Program's 2002 Scientific Assessment: Past, Present, and Future,
model calculations were made of free chlorine concentrations in the stratosphere
(Table 1).
As halogen source gas emissions decrease in the early 21st century, ozone
values are expected to increase and recover toward pre-1980 values. In
other words, we haven't, can't, and won't fix the "ozone hole" in
our lifetimes. The effects of CFCs are too persistent. CFCs act as catalysts
and not reactants. BUT we probably have taken the right steps to do so in the
future.
What We Have Done
We have learned to manage our affairs without chemicals which reach the stratosphere
and consume ozone. Refrigerants which don't deplete the ozone, cool our
homes and cars. Hydrocarbon polymerization solvents allow specialty polymerizations
such as those which produce packaging film you can't tear open.
In cleaning work, we have learned that it was the low surface tension of
CFC-113 rather than its solvency which explains its powers. We have replaced
CFC-113
with other cleaning agents, and other cleaning processes. Today, hardly
any of my consulting business relates to replacements for CFC-113.
Will We Do it Again?
Global climate change (warming) now concerns atmospheric scientists, political
leaders, and ordinary citizens. The concern is about the effects of retention
in the stratosphere of emitted gasses (HFCs, PFCs, and SF6) with a high specific
heat. But CO2 is of greatest concern because its emission volume from fuel
combustion dwarfs all others.
Only superficially is the situation with greenhouse gases today similar to
the situation with CFCs in the 1980s.
Natural sources of greenhouse gases, not human-controlled sources of
CFCs, comprise most emissions.
The scientific relationship between measured global effects and emissions
is not as clearly defined and accepted as with CFCs.
The economic impacts and effects on infrastructure of both action
and no action are much greater than with CFCs.
A critical mass of political leadership has yet to emerge and
galvanize global action. When will it, and what form will it
take?
John Durkee is an independent consultant specializing in critical cleaning
for contamination control. Contact him at PO Box 847, Hunt, TX 78024 or 122
Ridge Rd. West, Hunt, TX 78024; 830-238-7610; Fax 612-677-3170; or jdurkee@precisioncleaning.com
