High ammonia concentrations in intensive pig housing cause respiratory damage and discomfort. The air quality welfare challenge in pig farming reveals how production density creates systemic health problems.
Respiratory welfare in intensive pig farming involves chronic exposure to ammonia concentrations that cause ongoing discomfort and damage to the respiratory tract. Ammonia at concentrations above 10-20 ppm causes chemical irritation equivalent to chronic mild acid exposure of the airway lining. This irritation impairs immune defence against respiratory pathogens, reduces mucociliary clearance, and causes pain sensations comparable to breathing in polluted air. Stockworkers in high-ammonia pig buildings require respiratory protection, yet the pigs living in these spaces have no such protection. Ventilation technology enabling lower ammonia concentrations is available but investment is not universally required. The welfare case for mandatory ammonia monitoring and ventilation standards in pig housing is strong and supported by evidence from productivity as well as welfare research.