To what extent do chickens suffer when gassed with CO2? (2026)

Mace, J. L., Knight, A.

Abstract

On 9 th June 2025, in an apparent world first, undercover footage of chickens being gassed to death, in the UK in 2024, was publicly released (Carbstrong, 2025). The footage depicts a CO2 gas pit system within which crated chickens are mechanically lowered into increasing concentrations of CO2 (Royal Society for the Prevention of Cruelty to Animals [RSPCA], 2025; p. 82). Specifically, the footage captured the CO2 stunning of laying hens (Carbstrong, 2025)-laying hens of roughly 1.5 years of age who are no longer sufficiently productive to be of laying value to the egg industry. According to Carbstrong (2025), this includes hens from farms certified with the UK higher welfare label of RSPCA Assured. The Independent covered this news story and featured commentary from an RSPCA Assured spokesperson who had seen a longer nine-minute clip (Dalton & Colley, 2025). According to The Independent, the RSPCA spokesperson dismissed any welfare concerns arising from the footage, stating: The birds in the footage were already unconscious and were not in pain. The following short article seeks to highlight the flaws within this blanket statement, and to suggest what the RSPCA could instead be advocating, as a leading UK animal welfare organisation and a provider of higher welfare labelling (RSPCA Assured, 2025a).