How does fluorocarbons get into the atmosphere

There is one major problem, however, with HFCs — they act as classic greenhouse gases, causing global warming like carbon dioxide CO2 , though in this respect some HFCs are up to 10, times more effective than CO2. In order to better understand both the contribution made by HFCs to global warming and their chemical life cycle in the air, reliable estimates are necessary of the amount of these substances in the atmosphere.

This is not an easy task, particularly at the beginning of the marketing cycles of such products when production quantities are small and therefore emission levels are low. This is the case for the two foaming agents pentafluoropropane technically known as HFCfa and pentafluorobutane HFCmfc. The question is, will we see traces of them in the atmosphere, and if yes, then when? Because of its location — simultaneously at high-altitude in the Alps and yet in the middle of the heavily industrialized European continent — and the very low level of local contamination, this research station is perfectly placed for research into atmospheric emissions.

At the same time the Empa team also analyzed the air samples for CFC, a first generation foaming agent which has been banned in Europe since , and for HCFCb, its erstwhile second generation substitute, also banned since The conclusion the papers reach is that practically as soon as these substances are manufactured Empa researchers are able to detect them in the atmosphere, and in the minutest quantities imaginable.

This means one molecule of substance X to a quadrillion i. The pollutants are also to be found in the air around Tasmania, even though they are produced and used industrially exclusively in the northern hemisphere.

All told the global emissions of both substances at present are still relatively minor. This is despite the fact that both chemicals have a greenhouse effect which is between eight hundred and a thousand times stronger that than of CO2.

However the emissions of both HFCs increased massively over the last few years, and if this trend continues they could in future play a more significant role in the global warming phenomenon. For example, in HFCfa could not be detected in the atmosphere. Just one year later Empa measurements showed that global emissions of this substance had reached about tonnes, and by it had reached tonnes.

HFCmfc measurements tell a similar tale, with an increase from tonnes in to about tonnes in Some effects of global climate change include:. Use of CFCs is restricted to equipment placed into use prior to The production or import of HCFC and HCFCb for use in new units or applications was banned in the US as of January 1, , although production and import for use in existing equipment is allowed through Under these Rules, most HFC uses in polyurethane and other foams and in new retail food refrigerated cases will be phased out between January 1, and January 1 Use of HFCs in mobile air conditioning will end with Model Year , while prohibitions on HFC use in new fire suppression systems, cold storage, residential refrigeration, and building chillers go into place on January 1 of , , and , respectively.

In addition to the various production bans, servicers and disposers of appliances and motor vehicle air conditioners are required to obtain technician certification, proper refrigerant recovery or recycling equipment, and keep records. Skip to main content. Atmospheric researchers have determined the rates at which several CFCs react with hydroxyl radicals; the lifetimes for these CFCs with respect to hydroxyl radicals is approximately 80 years.

In other words, if hydroxyl radicals were the only thing reacting with the CFCs, it would take 80 years to completely remove them from the atmosphere. That is a long time! In comparison, methanol, a component of some alternative fuels, has a lifetime with respect to hydroxyl radical reaction of just 17 days. Ozone and nitrate radicals are even less effective at breaking down CFCs.

Sherwood Rowland of the University of California at Irvine, who won a Nobel Prize for his work on atmospheric chemistry, answers: "This is indeed a persistent question--so much so that the most recent report of the World Meteorological Organization, entitled 'Scientific Assessment of Ozone Depletion: ,' included it among a list of common questions that have been persistently raised and long since answered. We had as many as 22 of them, but pared them down to the most frequently asked ones.

Although the CFC molecules are indeed several times heavier than air, thousands of measurements have been made from balloons, aircraft and satellites demonstrating that the CFCs are actually present in the stratosphere. The atmosphere is not stagnant. Winds mix the atmosphere to altitudes far above the top of the stratosphere much faster than molecules can settle according to their weight.

Gases such as CFCs that are insoluble in water and relatively unreactive in the lower atmosphere below about 10 kilometers are quickly mixed and therefore reach the stratosphere regardless of their weight. Much can be learned about the atmospheric fate of compounds from the measured changes in concentration versus altitude.

For example, the two gases carbon tetrafluoride CF 4 , produced mainly as a by-product of the manufacture of aluminum and CFC CCl 3 F, used in a variety of human activities are both much heavier than air. Carbon tetrafluoride is completely unreactive in the lower There have also been measurements over the past two decades of several other completely unreactive gases, one lighter than air neon and some heavier than air argon, krypton , which show that they also mix upward uniformly through the stratosphere regardless of their weight, just as observed with carbon tetrafluoride.