In the 1920s, refrigeration and air conditioning systems used compounds such as ammonia, chloromethane, propane and sulfur dioxide as refrigerants. However, the compounds were toxic and flammable, which made them dangerous. As a result, a team of chemists at Frigidaire sought safer alternatives, focusing on nontoxic, nonflammable alternatives consisting of carbon, fluorine and chlorine mixtures called chlorofluorocarbons (CFCs). One of the first CFC mixtures was called “Freon”, which ultimately came to be the dominant refrigerant used for many years.
By the early 1970s CFCs were widely used with worldwide production reaching nearly one million tons per year. Beyond refrigeration systems, a key market for CFCs was in consumer aerosol products, such as hair spray, bug sprays (pesticides), and spray paints. In the same decade, discoveries by researchers in Europe and North America made it increasingly obvious that humans were beginning to have a measurable impact on the environment. In the mid-1970s, groundbreaking work by University of California-Irvine researchers, F. Sherwood Rowland and Mario J. Molina, showed that CFCs in the atmosphere create a chain reaction and that one CFC molecule could destroy thousands of ozone molecules.
It was well understood that the ozone layer, which served as a protective barrier against the sun’s ultravioloet rays, was a critical element that made life possible on this planet. Therefore, this discovery was significant as Rowland and Molia posited that this chain reaction could deplete the ozone layer for years even if CFC use stopped immediately. During an interview with Chemical & Engineering News in 2007, Rowland noted, “When we realized there was a very effective chain reaction, that changed the CFC investigation from an interesting scientific problem to one that had major environmental consequences. You don’t often get many chills down your back when you look at scientific results,” he added, but that had been one of those moments.
It wasn’t until 1984 that NASA satellites detected an enormous hole in the ozone layer over Antarctica that Rowland and Molina’s work was confirmed (they later won the Nobel Prize for this work in 1995). As the news of the ozone hole spread and subsequent images showed the hole getting larger, this brought more public attention to the issue, which came to a head in the 1990s. Key legislation was formed in the U.S and, under an international treaty known as the Montreal Protocol, the production of CFCs would be banned or phased out in most developed countries.
With the ban of CFCs, both the release of CFCs during consumer use and the disposal of CFC-containing aerosol products to landfills and recycling facilities ceased, which was a turning point for the reduction of CFC impacts. Subsequent NASA imaging performed has demonstrated that the hole in the ozone layer has disappeared, although the thickness of the layer over Antarctica is still not what it was before CFC production. Yet, scientists predict the hole will fully heal in the next 2 – 3 decades assuming no additional issues arise.
The CFC story is a shining example of how scientific research informed a significant environmental challenge and how this research was used to guide policy to take appropriate actions. In this situation, the CFC production was halted which effectively eliminated the problem. It is also not that dissimilar to some of the challenges we face today, such as with PFAS.
Yet unlike with CFCs, the regulatory actions related to PFAS thus far have largely focused on where PFAS goes after production, such as during use and disposal, rather than on the production side. The science related to health and environmental impacts from PFAS at high concentration exposures has been around for over a decade and is reasonably well documented. On the other hand, long-term impacts at lower environmentally relevant concentrations is still evolving. Clearly, more research is needed to advance a more complete understanding of PFAS impacts. But if history is a guide, this suggests that current policymaking may benefit from some of the lessons learned regarding how CFCs were handled.