Alternatives exists: CO2 is particularly distressing and painful but Nitrogen or Helium instead would be imperceptible by the animals (hypoxia), just like some assisted suicide in the Swiss Confederation.

Related in neighbor countries:

- British Government reopens CO2 plant 'to sustain animal slaughter' despite calls for phase out https://theecologist.org/2026/may/15/pig-gas-slaughter-backe...

- French judicial precedent holds that publishing videos from farms unlawfully interferes with the owner's peaceful enjoyment of their property, even when they expose alleged animal welfare violations https://www.courdecassation.fr/en/decision/668e2422fcf93851f...

Pigs, chickens, rats, and humans all have different thresholds and responses to hypoxia, and CO2 in particular. What might be humane for humans can be extremely distressing and painful for a particular animal, and vice-versa. There's a significant amount of research exploring these responses. The gassing protocols are driven by solid science; alot more solid than nitrogen asphyxiation for humans. Though, how well the protocols are followed is a different matter.