Intensive animal farming or industrial livestock production, also known as factory farming, is a production approach towards farm animals in order to maximize production output, while minimizing production costs. Intensive factory farming has grown to become the biggest threat to the global environment through the loss of ecosystem services and global warming.

Industrial production of pigs and poultry is an important source of Green House Gas (GHG) emissions and is predicted to become more so. On intensive pig farms, the animals are generally kept on concrete with slats or grates for the manure to drain through. The manure is usually stored in slurry form (slurry is a liquid mixture of urine and feces). During storage on farm, slurry emits methane and when manure is spread on fields it emits nitrous oxide and causes nitrogen pollution of land and water. Poultry manure from factory farms emits high levels of nitrous oxide and ammonia.

European legislation in respect of animal living conditions put strict norms on air quality inside animal stables. EU Directive 98/58/EC (Annex Clause 10) states animal buildings should maintain living conditions not harmful for the animals in respect of gas concentrations among other things.