Fig. 13.

a NH₃ emissions from fertilizer applications and b from livestock (as total MT) for different regions of the country and recent changes, and c emission for 2014 by animal type. Data were derived from the EPA National Emissions Inventory (NEI) (https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data). The 10 regions of the US are as designated by the Office of Management and Budget (see also Online Resources Fig. S1). Note that Hawaii is included in Region IX and Alaska in Region X. Symbols used are from Vectorstock used under an expanded license