Farmed Hen Ammonia Exposure and Respiratory Welfare

Ammonia from accumulated manure is a pervasive air quality problem in poultry facilities causing chronic respiratory disease and eye damage in laying hens.

Key Facts

Ammonia concentrations in poorly ventilated poultry houses can reach 50-100 ppm or higher
Regulatory thresholds for human workers are typically 25 ppm — hens are often exposed to higher levels
Chronic ammonia exposure causes keratoconjunctivitis (eye inflammation), corneal ulcers, and blindness
Respiratory lesions from ammonia exposure are found in a significant proportion of hens at slaughter
Effective ventilation and litter management can maintain ammonia below 10 ppm in well-run facilities
Hens with eye disease show altered foraging behavior and reduced access to food and water

Welfare Considerations

Ammonia toxicity in laying hens is a welfare problem that is invisible in inspection photos and rarely communicated to consumers. Hens living in elevated ammonia environments experience chronic eye and respiratory inflammation that causes pain, impaired vision, and reduced quality of life throughout their productive lives. The corneal damage and respiratory lesions found at slaughter represent the cumulative welfare cost of inadequate air quality management. The problem is technically solvable — adequate ventilation and litter management control ammonia effectively — but requires investment that many facilities avoid.

What You Can Do

Choose eggs from cage-free or pasture-raised systems with documented ventilation standards
Advocate for mandatory ammonia monitoring and maximum thresholds in egg production facilities
Support welfare certification programs that include air quality as a monitored parameter
Reduce egg consumption or switch to plant-based alternatives to decrease demand
Donate to organizations researching and advocating for improved poultry air quality standards