Pig CO2 Stunning Welfare Science

CO2 stunning, used widely in commercial pig slaughter, causes a period of aversion and distress before loss of consciousness that welfare scientists argue makes it an inadequate humane killing method.

Key Facts

Over 90% of UK pigs are stunned with CO2 before slaughter
Research shows pigs show strong aversion to CO2 gas, including escape attempts and distress vocalisations
The period of consciousness during CO2 induction lasts 15-30 seconds, during which pigs experience significant distress
Alternative methods including high concentrations of nitrogen or argon gas cause less aversion
Electrical head-only stunning is another alternative but requires careful application for efficacy
UK and EU regulators have acknowledged the welfare concerns of CO2 stunning but replacement has been slow

Welfare Considerations

CO2 stunning is the most widely criticised aspect of commercial pig slaughter from a welfare perspective. The evidence is clear that pigs experience significant distress during CO2 induction. Welfare scientists, including those advising the UK government, have called for a transition to less aversive gases. The primary barrier to change is cost and industry inertia rather than technical feasibility.

What You Can Do

Support campaigns by organisations like Humane Slaughter Association for CO2 alternatives
Choose pork from producers committed to transitioning to less aversive stunning methods
Contact your elected representatives about the scientific evidence on CO2 stunning
Reduce pork consumption as a way to reduce your contribution to this welfare concern
Advocate for a firm regulatory timeline for CO2 stunning phase-out in commercial pig slaughter