From: veritasium
Before the development of modern refrigerants, common gases used in refrigerators included methyl formate, which is highly toxic, and sulfur dioxide, which is flammable [00:20:22].
Development of Freon
In 1928, engineer Thomas Midgley Jr. was tasked by General Motors (GM) to create a safer alternative to existing refrigerants for household appliances like fridges [00:20:11]. Midgley developed dichlorodifluoromethane, a non-toxic and non-flammable refrigerant [00:20:33]. GM named this new product “Freon” [00:20:41]. To demonstrate its safety, Midgley publicly inhaled a lung full of Freon and blew out a candle at the American Chemical Society unveiling [00:20:45].
Widespread Use and Environmental Consequences
In the decades following its invention, Chlorofluorocarbons (CFCs), such as Freon, became widely popular [00:20:54]. They were also utilized as solvents and in aerosols [00:20:57].
However, CFCs pose significant environmental problems because they are light and stable [00:21:01]. When released into the atmosphere, CFC molecules rise into the stratosphere and can remain there for 50 to 100 years [00:21:05]. If a CFC molecule is struck by an ultraviolet photon of specific energy, it breaks apart, releasing a chlorine atom [00:21:14]. This chlorine atom then reacts with ozone, breaking it down into chlorine monoxide and oxygen gas [00:21:20].
This process led to an environmental disaster: the hole in the ozone layer [00:21:29]. A depleted ozone layer allows more UV light to penetrate the atmosphere, increasing rates of skin cancer and cataracts [00:21:32]. Furthermore, CFCs are potent greenhouse gases, contributing 10,000 times more warming per kilogram than CO2 [00:21:40].
The historian John McNeil noted that Midgley had “more impact on the atmosphere than any other single organism in Earth’s history” [00:21:47].
Global Response and Recovery
In response to the growing environmental concerns, the Montreal Protocol, an international agreement to phase out CFCs, went into effect in 1989 [00:21:54]. As a result, the ozone layer is now showing signs of recovery, although full recovery is expected to take many more decades [00:22:02].