Pig Housing Ventilation and Air Quality Welfare

Poor air quality in pig housing is a major but underappreciated welfare problem, with ammonia and particulate matter causing respiratory damage and chronic discomfort.

Key Facts

Recommended maximum ammonia levels in pig housing are 20 ppm — levels above this cause respiratory irritation
Studies in commercial pig buildings routinely record ammonia above 20 ppm, particularly in poorly managed deep-pit systems
Particulate matter from dried faeces, feed dust, and skin debris reaches concentrations 100x outdoor levels in poorly ventilated buildings
High ammonia causes conjunctivitis, rhinitis, and chronic bronchitis in pigs and in human farm workers
Natural ventilation through ridge outlets and side inlets can maintain adequate air quality in most climates
Slatted floor systems allow faeces to fall below the pig level, reducing ammonia accumulation if pit ventilation is adequate
Scrubber systems that pass exhaust air through acid baths reduce ammonia emissions by 70-80%
Air quality is directly linked to respiratory disease prevalence — farms with low ammonia consistently show lower pneumonia rates

Welfare Considerations

Air quality is an invisible welfare dimension of pig housing: pigs cannot escape the building and experience continuous exposure to ammonia, dust, and pathogens across their entire production life. Chronic ammonia exposure causes persistent respiratory irritation and mucosal damage that impairs the immune barrier against respiratory pathogens, creating a direct link between air quality and disease welfare burden. Pigs in high-ammonia environments show higher rates of coughing, nasal discharge, and lung lesion at slaughter. The welfare investment in adequate ventilation — maintaining ammonia below 10 ppm and providing meaningful air movement — is both protective of pig welfare and of human worker health.

What You Can Do

Support regulatory requirements for maximum ammonia limits in pig housing with enforcement mechanisms
Advocate for natural ventilation design requirements in pig building planning approval
Choose pork from producers certified to higher welfare standards requiring air quality monitoring
Fund research into low-cost ammonia scrubbing technology for small-scale pig producers
Encourage pig producers to install ammonia sensors for continuous air quality monitoring
Push for ventilation standards to be included as mandatory in veterinary health plan requirements for pig farms