Poor indoor air quality in intensive pig units — characterised by high ammonia, hydrogen sulphide, dust, and pathogen loads — causes chronic respiratory disease and represents a major preventable welfare burden.
Chronic respiratory exposure to poor air quality in pig buildings causes ongoing welfare harm that accumulates over months. Pigs living with nasal and bronchial irritation from ammonia are in a state of chronic low-grade discomfort that predisposes them to respiratory infection. Enzootic pneumonia causes persistent cough and reduced growth — signs of lung pathology that affect welfare even in subclinical cases. The relationship between air quality and welfare is both direct (irritation and disease) and indirect (immune suppression that increases susceptibility to secondary infections). Ventilation management is a core stockperson welfare responsibility; buildings that are not properly ventilated condemn pigs to preventable suffering. Investment in air scrubbers and slurry management technology represents a welfare improvement that also reduces environmental and neighbour impact, aligning welfare and sustainability goals.