Air quality in intensive livestock buildings — particularly ammonia and particulate matter concentrations — is a significant but underregulated welfare determinant for billions of farmed animals.
Air quality in intensive livestock buildings is an invisible but pervasive welfare problem: ammonia, particulate matter, carbon dioxide, and pathogenic microorganisms create chronic respiratory stress that impairs health and quality of life for billions of animals throughout their production lives. Unlike acute welfare events that trigger visible suffering, poor air quality causes gradual damage — irritated eyes, inflamed airways, suppressed immune function, reduced appetite — that accumulates over weeks and months of continuous exposure. Farm audit systems rarely include air quality measurement as a welfare indicator, relying instead on structural standards that may not ensure adequate ventilation in practice. Outcome-based welfare standards that include respiratory health indicators — eye damage rates, respiratory disease rates, lung lesion scores at slaughter — would provide a more honest assessment of air quality welfare impacts than ventilation specifications alone.