High ammonia concentrations in poultry houses cause painful eye and respiratory damage to billions of chickens annually and represent a widespread, preventable welfare failure.
Ammonia-induced eye damage in poultry is both common and underappreciated. Chickens kept in high-ammonia environments develop progressively worsening eye conditions — starting with irritation and progressing to corneal opacity that impairs vision. Affected birds show reduced activity, social withdrawal, and reduced feed intake consistent with pain. The fact that chickens actively choose to avoid ammonia-contaminated environments when given the option demonstrates they experience it as aversive. Better air quality management through ventilation and stocking density reform would eliminate this widespread source of suffering.