In the late seventies, the discovery that some molecules could have a very severe effect on the ozone layer has prompted the international community to enact stringent regulations on their production and/or uses. The Montreal Protocol on substances that deplete the ozone layer is influencing the use of blowing agents. This international treaty is designed to protect the ozone layer by phasing out production of certain substances responsible for ozone depletion. The treaty is structured around several groups of halogenated (mainly chlorine and bromine based) hydrocarbons that have been shown to play a role in ozone depletion. Fluorine does not harm the ozone layer. This international agreement provides a phase-out schedule that will differ depending on types of substances considered and groups ("developed countries" and "article 5 countries") countries belong to. For the products used as blowing agents in polyurethane foams, the production of CFCs in developed countries was forbidden as of 1/1/1996 according to the Montreal Protocol. The "article 5 countries" will have until 2010 to end their production of CFCs. HCFCs have also been included and have an elimination schedule of 2020 (gradual reduction from 2004 to 2020) for the developed countries and 2040 for the article 5 countries (gradual reduction from 2016 to 2040). Within the frame of this protocol, some countries such as the United States and the European Union have decided to take further steps towards the total phase-out of all ozone depleting substances. The United States has decided, for example, HCFC-141b will have to be phased-out in 2003. Meanwhile, the European Union phased out CFCs on 1/1/1995. It has further placed restrictions on the uses of the HCFCs, limiting them to non-emissive applications such as rigid insulating foams. In the European Union, HCFCs will be eliminated in 2014. This latest regulation can even lead to some unexpected results. In the European Union, using HCFCs for flexible or integral skin polyurethane foams is therefore forbidden, but the use of CFCs is not. Since CFCs (CFC-11 in the case of rigid polyurethane foams) have by far the greatest Ozone Depletion Potential, the most effective way to help restore the ozone layer is to stop using them as soon as possible. In developed countries, the phase-out of CFC-11 was made possible by the availability of substitutes (HCFC-141b in the US, HCFC-141b and hydrocarbons in the European Union). The phase-out of CFC-11 in foams, along with those ozone depleting substances used in other applications (aerosols, refrigeration, fire extinguishers), has already proven to be successful. Recent measurements of the atmospheric chlorine loading clearly show that we are on the right track. The equivalent effective chlorine content in the northern troposphere (lower layer of the atmosphere) has been decreasing for a few years. Under the Montreal Protocol, the US and other developed nations must achieve a certain percentage of progress towards the total phaseout of production and consumption of HCFCs, by certain dates.

Comparison of the Montreal Protocol and United States Phaseout Schedules
Montreal Protocol		United States
Year to be Implemented	% Reduction in Consumption & Production, Using the Cap as Baseline	Year to be Implemented	Implementation of HCFC Phaseout through Clean Air Act Regulations
2004	35%	2003	No production and no importing of HCFC-141b
2010	75%	2010	No production and no importing of HCFC-142b and HCFC-22, except for use in equipment manufactured before 1/1/2010 (no production or importing for new equipment that uses these compounds)
2015	90%	2015	No production and no importing of any HCFCs, except for use as refrigerants in equipment manufactured before 1/1/2020
2020	99.5%	2020	No production and no importing of HCFC-142b and HCFC-22
2030	100%	2030	No production and no importing of any HCFCs
Source Courtsey: EPA

Under the nonessential use ban, all foam products containing or manufactured with CFCs and HCFCs, except insulating foams, were banned in 1994 from sale and distribution in interstate commerce in the United States. The most commonly used HCFCs for foam blowing are HCFC-141b, HCFC-22, and HCFC-142b. EPA banned the use of HCFC-141b in 2003. EPA has also banned the use and sale of virgin HCFC-22 and HCFC-142b for foam blowing purposes as of January 1, 2010. The HCFC phaseout schedule under the Clean Air Act Amendments is found here. As of March 1, 2008, the use of HCFC-22, HCFC-142b, and blends thereof are unacceptable (prohibited) as substitutes for HCFC-141b in the manufacture of commercial refrigeration, sandwich panels, slabstock, and other "pour foam" applications. EPA allowed the use of HCFC-22 and HCFC-142b in the manufacture of foam for marine applications until September 1, 2009. All other foam blowing uses of HCFC-22 and HCFC-142b are prohibited as of January 1, 2010. In addition, HCFC-124 is unacceptable as a substitute in all foam blowing end uses.
Blowing agents also increase global warming. Their effect depends upon their chemical nature. UNDP has provided matrix of the different types of blowing agents and their impact on ozone depletion and global warming.

Blowing Agent Replacements for Plastic Foam Production
(Source: UN Industrial Development Organization)