We are calling on the Scottish Government to end the use of carbon dioxide (CO₂) to stun pigs before killing them in slaughterhouses.

We have been working tirelessly for decades to put an end to intensive farming practices, which cause immense suffering to the animals trapped in these systems.

Today, we sent a letter sent to the Minister for Agriculture and Connectivity, Jim Fairlie MSP, highlighting that the use of CO₂ stunning is an “urgent welfare risk”. The letter comes as the Animal Welfare Committee (AWC) recommended that UK governments prohibit CO₂ stunning as it inflicts avoidable pain, distress or suffering on pigs.

Why is CO₂ gassing cruel?

CO₂ gas dissolves in the mucous membranes of the eyes, nose, mouth and lungs, forming acid, which at current commercial concentrations of the gas, is likely to be severely painful for the pigs. Inhalation of the gas also leads to respiratory distress and the desperate feeling of ‘air hunger’, which the AWC reports “is associated with profound anxiety, frustration, fear and panic”. Fear and anxiety are exacerbated by pigs “experiencing a highly aversive yet inescapable environment.”

Read the letter

Jim Fairlie MSP
Minister for Agriculture and Connectivity
The Scottish Parliament
Edinburgh
EH99 1SP

Date: Tuesday 4th November 2025

Re: CO² stunning of pigs 

Dear Minister,

We have appreciated recent constructive engagement around phasing out the use of farrowing crates and look forward to continued progress on that issue.

This letter regards another urgent welfare risk for pigs: the use of CO² gas stunning. The Animal Welfare Committee (AWC) has just published its opinion on the issue and recommended that: “To prevent pigs experiencing avoidable pain, distress or suffering at slaughter associated with high concentration CO₂ [ or CO₂ in combination with inert gases] its use should be prohibited as a method of stunning for pigs. […] Any transition period given to industry to enable the change to alternative methods of slaughter […] should be as short as possible and in any case within five years.”

The harms caused by high concentration CO² stunning have been long understood; both the AWC’s predecessor, the Farm Animal Welfare Council (FAWC), and the European Food Safety Authority (EFSA) recommended more than two decades ago that this practice should end. EFSA reiterated that recommendation in 2020.

Will the Scottish Government follow the recommendations of these expert government advisory bodies and prohibit the use of CO² stunning for pigs?

CO² gas dissolves in the mucous membranes of the eyes, nose, mouth and lungs, causing pain. At current commercial concentrations of the gas that pain is likely to be severe. Inhalation of the gas also leads to respiratory distress and the desperate feeling of ‘air hunger’, which the AWC reports “is associated with profound anxiety, frustration, fear and panic”. Fear and anxiety are exacerbated by pigs “experiencing a highly aversive yet inescapable environment.”

Putting pigs through such intense pain and distress in their final moments is unacceptable.

We understand that following these recommendations in Scotland would primarily affect the Brechin abattoir, as it is the only large-scale pig abattoir and currently uses CO² in a controlled atmosphere stunning system. Such a system could be converted to use argon gas which, while not without welfare concerns, does not cause pain or air hunger and so is significantly less aversive. Converting to argon would continue to allow pigs to be stunned in small groups with minimal handling and restraint, avoiding isolation or handling stress related to some other alternatives.

We also understand that some in the industry are opposed to such a change and that it would potentially slow down slaughter processes. However, this necessary welfare protection cannot be postponed to save time or money. As the AWC has stated, “the use of an aversive or painful method to allow for greater throughput or cost-cutting is not justifiable.”

We look forward to hearing how the Scottish Government will tackle this grave and longstanding animal welfare concern.