I would like express gratitude to the HSA for their 20 years of tireless advocacy for improving pigs' welfare. Their efforts have empowered those seeking alternatives to carbon dioxide stunning. Over nearly 30 years, I've worked on animal welfare friendly stunning applications, particularly regarding stunning/slaughtering using nitrogen foam, and I believe I've found the definitive answer. The industry originally adopted large-scale carbon dioxide stunning to optimize food production, reduce costs, and lower meat prices, which is only feasible with parallel processing (simultaneously stunning groups of pigs) rather than serial processing (stunning each pig individually). Electrocution is not viable for large-scale operations due to this need for parallel processing. Therefore, a replacement gas that lacks carbon dioxide's detrimental properties is needed, but only a few gases are suitable. Additionally, the application of an alternative gas must adhere to several fundamental principles: a) Applicability of the methods for stunning and killing pigs, including their scalability for large-scale application. b) Description of the technical. c) Animal welfare consequences associated with specific techniques, including welfare hazards (ABMs), animal-based indicators (ABIs), preventive and corrective measures, and the sufficiency of scientific literature in describing these consequences. d) Applicability under field conditions. Introducing a novel application for large-scale pig slaughter is complex and time-consuming before it can be expected, especially given the substantial economic and financial impact for the industry. However, there is hope on the horizon. The alternative gas is nitrogen, and the application is based on using high-expansion foam filled with 100% nitrogen, applied in a closed container. Within a minute, all air is displaced by the foam, after which the container is sealed, and the foam is broken down with a powerful nitrogen pulse. This ensures that the foam does not affect the stunning process; the entire process can be visually and electronically monitored, and the residual oxygen level in the container is consistently below 2%. The container dimensions are identical to the gondolas used in the globally implemented carbon dioxide gondola system. The integration of nitrogen foam technology into European regulation EU1099/2009 is nearing completion. All scientific and technical procedures have been submitted to the EU Commission, with finalization awaiting the presentation of EFSA's scientific opinion to the Commission and subsequent approval for inclusion. This final phase is anticipated to occur during the general meeting slated for June 2024. This marks the first step toward replacing carbon dioxide in 25 years. Fingers crossed for the EU Commission's decision in June 2024! Harm Kiezebrink Independent Expert

1. FOR IMMEDIATE RELEASE
15 May 2024
Study 0unded by HSA and DEFRA fnds Low Atmospheric Pressure Stunning is not a
humane alternative to Carbon Dioxide 0or stunning pigs. Alternatives must now be
urgently implemented.
The Humane Slaughter Association’s position regarding the slaughter o6 all animals is that they
should be killed as humanely as possible with every reasonable e<ort made to reduce pain,
su<ering and distress to an absolute minimum.
Carbon Dioxide (CO2) is widely used to stun pigs prior to slaughter. However, robust scientifc
evidence shows that it causes signifcant animal wel6are issues. As early as 2003, the then UK
Farm Animal Wel6are Council (FAWC) called 6or CO2 to be phased out within fve years1
, yet two
decades later this method continues to be widely used (6or example, in the UK, over 80% o6 pigs are
stunned with CO2). The HSA view is that a more humane alternative to CO2 should be adopted as
soon as possible.
In support o6 this aim, in 2018 the HSA co-6unded research alongside the UK Department 6or
Environment, Food and Rural A<airs (DEFRA) to test one potentially humane alternative stunning
method – Low Atmospheric Pressure Stunning (LAPS). Un6ortunately, the research showed that
LAPS was not a humane alternative 6or stunning pigs, although it had previously been shown to be
a more humane method o6 poultry slaughter. The researchers conclude that “Collectively, our
results show that both LAPS and CO2 stunning are associated with several indicators o6 poor
wel6are and are equally aversive to pigs.” The fnal report2
detailing the project fndings has just
been published and can be downloaded at:
https://sciencesearch.de6ra.gov.uk/ProjectDetails?ProjectId=19805
It was important to test a method which could potentially have provided a humane and sustainable
solution 6or pig stunning. However, now that LAPS has been shown not to be the alternative to CO2
that many had hoped, it is essential that other alternatives are adopted without undue delay.
Background – wel0are impacts o0 existing pig slaughter methods
In the UK and Europe, all pigs are stunned be6ore slaughter and two commonly used methods
exist: stunning with carbon dioxide gas or electrical stunning. Both methods have advantages and
disadvantages in terms o6 animal wel6are.
Carbon dioxide
This method involves exposing pigs to a high concentration o6 CO2 gas which renders them
unconscious. In the UK, regulations require pigs to be killed by extended exposure to CO2, whereas

2. in other countries, pigs can be rendered unconscious by CO2 and then killed using another method,
typically by cutting the arteries and veins in the neck to kill the animals by blood loss.
Carbon Dioxide has been shown to be strongly aversive to pigs (3,4) (and almost all other
mammals in which it has been tested), because it causes breathlessness or pain in high
concentrations and anxiety even at lower concentrations. Given these wel6are issues, the HSA
recommends that CO2 is replaced with a more humane method as soon as possible.
Electrical stunning
Electrical stunning is typically per6ormed by passing electrical current through the pig’s brain using
electrodes placed on either side o6 the pig’s head. When per6ormed correctly, the pig is rendered
unconscious instantaneously. Once pigs are unconscious, they are then killed by bleeding.
When correctly used, electrical stunning causes less su<ering than CO2 during the actual stunning
process. However, when considering the overall animal wel6are impact o6 di<erent stunning
methods, it is important to consider the entire slaughter process, including handling prior to
slaughter. To apply electrical stunning, pigs are o6ten handled in ways which can cause them more
stress than the handling procedures used 6or CO2 stunning as they are usually separated 6rom their
group or placed in restrainers, in single fle, prior to stunning. There is also a greater risk o6
inadequate stunning i6 electrical stunning is not per6ormed correctly.
The current systems 6or CO2 stunning allow pigs to be handled in groups. As pigs are social
animals, this can help them stay calmer. Stunning is also automated, reducing the risk o6 error.
Despite these advantages o6 CO2 stunning systems, they do not negate the negative wel6are
impacts o6 CO2 exposure. There6ore, CO2 should be replaced with a more humane system whilst
retaining the handling and automation advantages.
What are the alternatives?
Although personal opinions and choices on the consumption o6 pork vary greatly, the slaughter o6
pigs is likely to continue 6or the 6oreseeable 6uture as many people will continue to choose to eat
pork. There6ore, more humane slaughter methods are necessary.
It is o6ten suggested that there are no viable alternatives to CO2 which could be rapidly adopted.
However, modifcations to existing electrical and gas stunning systems could potentially make
them more humane.
It was conclusively shown in the 1990s that inert gases such as argon are less aversive than CO2 to
pigs and could replace itin gas stunning systems (3,4). Electrical stunning could be combined with
more humane handling systems which allow animals to be handled in groups.
Inert gas stunning systems are a particularly promising solution, not least because they can be
retroftted into existing CO2 stunning equipment. However, these systems have not been
implemented by the industry yet, despite the 2003 FAWC report stating “Development work is
required to produce a new system 6or use with argon, nitrogen or other non-aversive gas mixtures.
FAWC does not see the achievement o6 engineering solutions as an insurmountable problem.”1
Nevertheless, engineering challenges to switching to the use o6 inert gases still remain, and the
HSA urges the industry to address these without 6urther delay.
We are pleased to see that both approaches are being investigated alongside others as part o6 the
EU-6unded Pig Stun project which is examining several approaches including improved electrical
stunning and three di<erent gas-based systems. Crucially, it will test the use o6 inert gas systems
which can be retroftted to existing dip-li6t or paternoster systems which currently use CO2.
Given the disappointing fnding that LAPS is not a humane alternative to CO2 and that CO2 use
continues, the HSA is eager to work with the industry and regulators to help 6acilitate rapid
progress to address this major animal wel6are challenge.

3. Recently the pig sector has 6ormed a working group which aims to address this issue. We look
6orward to working with this group to address any remaining barriers to the adoption o6 a more
humane method and are encouraged that this issue is now receiving much-needed attention 6rom
those best placed to ensure progress.
HSA Chie6 Executive Huw Golledge said: “The HSA welcomes the pig sector’s initiative to urgently
investigate alternatives to CO2 Aor pre-slaughter stunning oA pigs. There are serious concerns,
based on robust scientifc evidence, about the impact oA CO2 stunning on pig welAare both
amongst animal welAare experts and increasingly amongst the public too. Progress towards a more
humane method has been too slow and the HSA would now hope to see rapid progress towards
replacement oA CO2, whilst acknowledging that signifcant practical challenges remain to be
solved. The pig sector will play a pivotal role in defning these problems and fnding solutions. We
look Aorward to working with the industry and other stakeholders to ensure that progress is as rapid
as possible.”
Re0erences
1. Farm Animal Wel6are Council Report on the Wel6are o6 Farmed Animals at Slaughter or
Killing Part 2: White Meat Animals -
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment
_data/fle/325241/FAWC_report_on_the_wel6are_o6_6armed_animals_at_slaughter_or_killi
ng_part_one_red_meat_animals.pd6
2. De6ra Project code: MH0154 - LAPS in pigs: a humane alternative to carbon dioxide? -
https://sciencesearch.de6ra.gov.uk/ProjectDetails?ProjectId=19805
3. Raj, A. B. M., & Gregory, N. G. (1995). Wel6are Implications o6 the Gas Stunning o6 Pigs 1.
Determination o6 Aversion to the Initial Inhalation o6 Carbon Dioxide or Argon. Animal
Wel6are, 4(4), 273–280.
4. Raj, A. B. M., & Gregory, N. G. (1996). Wel6are Implications o6 the Gas Stunning o6 Pigs 2.
Stress o6 Induction o6 Anaesthesia. Animal Wel6are, 5(1), 71-78.
ENDS
Notes to Editors:
The Humane Slaughter Association (HSA) is a UK-based, independent Charitable Incorporated
Organisation (CIO). It is the only UK charity concerned exclusively in promoting the humane
treatment o6 all 6ood animals during transport, at market, slaughter, and killing 6or wel6are reasons
or disease control.
It works through research, education, training and promoting technical advances to bring real,
practical and lasting improvements in 6ood animal wel6are.
The HSA is 6unded by voluntary donations, subscriptions and legacies. For more in6ormation about
the HSA’s work email in6o@hsa.org.uk or visit www.hsa.org.uk
Media Contact: Carly Halliday (media@hsa.org.uk)