Ammonia is a colourless gas with a pungent odor that is noticeable at concentrations above 50 ppm. Most of the NH₃ emitted is generated from livestock waste management and fertilizer production.

NH₃ is poisonous if inhaled in great quantities and is irritating to the eyes, nose, and throat in lesser amounts. It combines in the atmosphere with sulphates and nitrates to form secondary fine particulate matter (PM_2.5). PM_2.5 is known to have harmful effects on human health and the environment. NH₃ can also contribute to the nitrification and eutrophication of aquatic systems.

Related Websites:

http://www.ccme.ca/ourwork/air.html
http://www.ec.gc.ca/air/interim2001/minister_e.html
http://www.ec.gc.ca/CEPARegistry/default.cfm
http://www.ec.gc.ca/cleanair-airpur/Canada_US
http://www.unece.org/env/lrtap/