Air Quality Takeaways
Takeaways are key points detailed and referenced in the Air Quality section
Nitrogen, Air, and Animal Ag
Animal ag air pollution is complex, likely underestimated, and poorly regulated, though it is one of the nation’s largest sources of environmental harm.
Excess nitrogen spewed into the atmosphere is a form of nutrient pollution; ammonia from animal ag is one of the major conduits.
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 15-20% of all leaked nitrogen is emitted as ammonia, most of it from animal ag.
Ammonia
Ammonia (NH3), a nitrogen compound, 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 produces respiratory disease; local emissions also impact factory farm workers and nearby homeowners.
Portions of ammonia transform into fine particulate matter, known as PM2.5 ; PM2.5 is the largest environmental cause of premature human mortality in the U.S. and globally.
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.
PM2.5
PM2.5 is believed to be the cause of about 95% of air pollution-related deaths globally, and perhaps ~90% in the U.S.
Ammonia from agriculture is the source of about 20-30% of PM2.5. Ammonia from animal ag is responsible for about 15-20% of PM2.5 .
Ammonia-generated PM2.5 from animal ag is likely responsible for more than 10,000 deaths yearly in the U.S.
Like most negative externalities of animal agriculture, air pollution risks due to ammonia generation are typically underestimated and underreported; impacts on wildlife and natural systems are mostly unexplored.