UK proposes ending CO₂ stunning of pigs: why the method is criticised and what could replace it

What the government has proposed

On 26 October 2026 the Department for Environment, Food and Rural Affairs (Defra) opened a public consultation on plans to phase out the stunning of pigs before slaughter using high concentrations of carbon dioxide (CO₂). Instead, it proposes argon or automated electrical methods, which the department says significantly reduce animal suffering. Responses can be submitted until 21 December.

The proposal is based on a recommendation from the Animal Welfare Committee — an independent expert body that advises Defra and the governments of Scotland, Wales and Northern Ireland. Almost a year ago the committee recommended banning this stunning method. The consultation itself is a standard UK step before rules are changed: the government publishes a proposal, and anyone with an interest — from abattoirs to members of the public — can respond before a decision is made.

How pigs are stunned today

By law, in the UK and the EU, animals must be stunned before slaughter so that they are unconscious and feel no pain. Good stunning should be quick and reliable and should not itself cause suffering. Two main methods are used for pigs: electricity and gas.

At many large abattoirs, pigs are lowered in groups in a special cage into a pit filled with air containing a high concentration of carbon dioxide — usually 80% or more. The animals breathe in the gas and lose consciousness after a while. The method suits businesses: it can handle large numbers of animals, pigs don't need to be restrained one at a time, and they need less handling.

Why the method is criticised

The problem is that high concentrations of CO₂ are unpleasant and painful in themselves. When inhaled, the gas irritates the lining of the nose and airways, and the body perceives the excess carbon dioxide as suffocation. Before losing consciousness, pigs have been observed gasping, trying to escape and squealing. This phase lasts not an instant but several tens of seconds. By comparison, with correctly applied electrical stunning an animal loses consciousness in a fraction of a second.

In its scientific opinions on the welfare of pigs at slaughter, the European Food Safety Authority (EFSA) has also stated that high concentrations of CO₂ cause pain, fear and distress. That's why scientists and animal welfare campaigners have long called for an alternative. It's important to understand that this isn't about cruelty by individual workers: even when the rules are followed perfectly, the gas at this concentration is aversive to the animal. So the issue can't be solved by staff training — only by choosing a different method.

The alternative: argon

Argon is an inert gas found in small amounts in air that does not irritate the airways. If a pig breathes a mixture high in argon and almost free of oxygen, it loses consciousness from lack of oxygen but doesn't experience the sense of suffocation caused by CO₂: in mammals, the feeling of "not being able to breathe" is triggered specifically by an excess of carbon dioxide. Argon is heavier than air, so it can be used in similar pits. The downsides are that the gas is more expensive and animals may take longer to lose consciousness, so equipment and exposure time need very careful calibration. Scientists are also studying other inert gases — such as nitrogen, including in the form of a dense foam that fills the chamber. These methods are used less often for now, but they show that alternatives to carbon dioxide exist in practice, not just in theory.

The alternative: automated electrical stunning

In electrical stunning, a current is passed through the pig's head, causing instant unconsciousness. The problem with manual electrical stunning is human error: if the electrodes are placed incorrectly or the current is applied for too short a time, the animal may remain conscious. Automated systems restrain the animal and position the electrodes correctly themselves, which reduces errors. But they need a well-designed system for moving pigs forward one at a time so the animals don't become stressed in the queue. Often, head-only stunning is immediately followed by a current across the heart, so the animal doesn't regain consciousness. This method has long been used in many abattoirs, including small ones, so it isn't new to the industry.

What the committee and the minister say

The Animal Welfare Committee is the former Farm Animal Welfare Committee, which was given a wider remit in 2019. It provides the government with independent scientific advice on the welfare of farmed, companion and other kept animals. The committee's chair, Madeleine Campbell, says the evidence in favour of the alternatives is "compelling".

Continuing to stun with carbon dioxide is ethically unacceptable.

Madeleine Campbell, chair of the Animal Welfare Committee

Farming minister Stephen Morgan said the proposals would help ensure high animal welfare standards and reduce unnecessary suffering, and that the government intends to support farmers and abattoirs during the transition. The announcement doesn't specify how long the transition period would be or what support would look like — that is one of the subjects of the consultation.

Who is against

The Association of Independent Meat Suppliers (AIMS) is asking for the consultation to be paused until the UK's negotiations with the EU on sanitary and phytosanitary (SPS) rules are completed and it becomes clear how they will affect animal welfare law. The association's executive director, Jason Aldiss, warns that if British abattoirs have to invest in new equipment while overseas producers keep their old systems, imported meat will gain a price advantage. He fears that some production, investment and jobs will move abroad, and believes Defra should explain how it will prevent that.

The reference to the EU talks is no accident. In 2025 the UK and the EU agreed to negotiate an SPS agreement intended to make trade in animal products easier. Such an agreement may require UK rules in this area to align with EU ones. So the meat industry wants to know what the common rules will be before investing in new equipment. The association also says it will respond separately on other animal welfare and operational issues.

Who is in favour

The RSPCA Assured welfare certification scheme called the proposal a genuinely important step forward. Its chief executive, Toby Baker, asked Defra to produce a clear plan to help farmers and abattoirs move to the new methods. RSPCA Assured is a UK certification scheme linked to the RSPCA: it checks farms, transport and abattoirs against its own welfare standards, and products from these farms carry a special label on the packaging.

And in the EU?

In the EU, stunning pigs with high concentrations of CO₂ is still permitted under the common regulation on the protection of animals at the time of killing. But EFSA's scientific opinions and campaigners' demands have made the issue part of a wider debate on revising Europe's animal welfare rules. If the UK introduces a ban, it will be one of the first countries to abandon the method — and its experience will be closely watched in Europe. Hence the British meat processors' concerns: as long as neighbouring countries don't change their rules, the transition costs more only for British businesses.

How to have your say

Defra's public consultation is open to everyone: farmers, abattoirs, vets, organisations and members of the public. Responses can be submitted on the GOV.UK website until 21 December. The department will consider the responses before making a decision. To make your response useful, read the proposal itself, answer the questions to the point and, if you can, refer to facts or your own experience — for example, if you work in the industry or as a vet. Shoppers who care about animal welfare can already look at pork labelling: certification schemes such as RSPCA Assured check conditions on farm and at slaughter.

Not just slaughter

Stunning covers only the last minutes of a pig's life. Just as important for its welfare is how it lives on the farm: how much space it has, whether it has bedding and materials to root in and chew, how long the journey to the abattoir takes and how it is handled during loading and in the lairage before slaughter. Campaigners point out that calm handling and short journeys help the stunning itself too: animals that aren't stressed pass through every stage more easily.

What happens next

After 21 December, Defra will analyse the responses and decide whether to introduce a ban and on what timescale. If it goes ahead, abattoirs are likely to be given a transition period to replace equipment. The changes would affect large plants with gas systems most: they would have to either convert them to argon or switch to automated electrical lines. For pigs, this could be one of the most significant changes to slaughter rules in decades; for the industry, a serious test whose cost is still to be negotiated.