Air Quality Takeaways
Takeaways are key points detailed and referenced in the Air Quality section
Overview
Excess nitrogen spewed into the environment devastates natural ecosystems; ammonia from animal ag is one of the major conduits.
Animal ag air pollution is complex, likely underestimated, and poorly regulated, though it is one of the nation’s largest sources of environmental harm.
Ammonia
Ammonia (NH3), a form of nitrogen, is the central air pollutant from animal agriculture.
About two thirds of total U.S. ammonia emissions are from animal ag.
Farmed animal manure generates ~50% of ammonia emissions, and fertilizers on feed crops add another 15-20%.
Farmed animals, especially poultry and pigs, endure high levels of ammonia in confinement which produce respiratory disease; local emissions also impact factory farm workers and nearby homeowners.
Portions of ammonia transform into PM2.5 – the largest environmental cause of premature human mortality.
Ammonia is a major input to the nitrogen cascade, whereby the sequential transformations of escaped nitrogen atoms create cycles of damage in a variety of ecosystems.
Nitrogen
Of the proposed 9 planetary boundaries that define a safe operating space for humanity, the nitrogen cycle has most definitively entered the “high-risk” zone.
Though nitrogen pollution receives a small share of the attention given to climate change, there is reason to ask, “Is nitrogen the next carbon?”
About a third of the newly created reactive nitrogen is produced for fertilizer for feed crops.
Of the newly created reactive nitrogen in the animal ag cycle, 80% or more is lost to the environment.
About 15-20% of all leaked nitrogen is emitted as ammonia, most of it from animal ag.
Manure
Manure has been transformed from an asset to a liability by the concentration of manure on factory farms and the convenience and productivity of chemical fertilizers.
Probably a third or more of the nitrogen in manure escapes as ammonia.
Almost all the nitrogen in factory farm manure escapes to the environment, with ~10% applied to crops.
Weak regulations regarding factory farm air pollution can incentivize producers to facilitate ammonia emissions so that manure with low nitrogen levels will meet land-application requirements.