Chicken Houses Cause Inflammation

Commercial chicken houses are so crowded that there may be less than three-quarters of one square foot per bird. As many as 25,000 chickens are packed into one shed. This overcrowding creates high levels of ammonia fumes and fecal dust. A recent study determined that people who spend only three hours in such a building will experience "acute inflammatory reaction in the upper airways and increased bronchial responsiveness."
There was no mention of the welfare of the chickens.

Larsson, BM et al, "Airway responses in naive subjects to exposure in poultry houses." Am J Industrial Medicine, 1999 35:142-9.