The UK government has announced plans to ban the use of carbon dioxide (CO2) for stunning pigs prior to slaughter, citing concerns over animal welfare. The Department for Environment, Food and Rural Affairs (Defra) made the proposal public yesterday, emphasizing that CO2 stunning causes "unnecessary pain and distress" to pigs.

In England and Wales, CO2 is currently used to stun more than 90 percent of pigs before they are slaughtered. Defra stated that pigs are "highly sentient and intelligent animals, capable of experiencing pain and fear," and underlined the importance of reducing distress at all stages of handling and slaughter in line with its Animal Welfare Strategy.

The move has been welcomed by animal rights campaigners, including Project Slingshot, a pressure group formerly supported by Facebook co-founder Dustin Moskovitz. The group has conducted a high-profile campaign against CO2 stunning, featuring thousands of advertisements with comedian Diane Morgan on the London Underground, as well as projection events at Buckingham Palace and the Houses of Parliament. Naomi Hallum, Project Slingshot’s head, expressed relief that the practice would end, stating that public awareness of the effects of CO2 on pigs had generated significant outrage.

Opposition from industry representatives has been swift. Jonathan Powell of the National Pig Processors Association (BPA) cautioned that a rapid move away from CO2 could jeopardize the UK’s food security, given that no suitable alternatives are currently available at scale. Similarly, the British Pig Association (BPA) raised concerns about the viability of other methods such as argon gas, which, they say, has not undergone sufficient commercial testing. Argon is reportedly more expensive—costing around 2.5 times as much as CO2—and can take up to four minutes to kill a pig, impacting slaughterhouse throughput.

Lizzie Wilson, chief executive of the BPA, highlighted the operational challenges of switching away from CO2. She explained that abattoirs rely on maintaining high throughput to remain economically viable, and any reduction in capacity could cause significant disruptions.

Defra’s proposals mark a significant shift in the UK’s approach to animal welfare in pig slaughter, reflecting growing public and political concern over methods deemed inhumane. However, the government and industry will face challenges in identifying and implementing effective, humane alternatives that can meet both welfare standards and commercial demands.