2010 The Fertilizer Institute Health Effects of Ammonia
Ammonia: An Essential Chemical
Ammonia is a naturally occurring chemical in the atmosphere, as well as an essential man-made chemical. It is represented by the chemical formula NH3. Ammonia in this form is also known as ammonia gas or anhydrous (“without water”) ammonia. At room temperature, ammonia is a colorless, pungent-smelling gas and is lighter than air.
At minus 28 degrees Fahrenheit (-33 degrees Celsius), ammonia becomes a liquid. Ammonia easily dissolves in water. In this form, it is also known as liquid ammonia, aqueous ammonia or ammonia solution. In water, most of the ammonia changes to ammonium ions, NH4+.
Ammonia is an essential element for plant, animal and human life.
It is found in water, soil and air, and is a source of much needed nitrogen for plants and animals. Most of the ammonia in the environment comes from the natural breakdown of manure, dead plants and animals. Man-made sources of ammonia include fertilizers, power plants, mobile sources and other manufacturing emissions. Due to its widespread presence in the environment and its many uses, questions often arise about its potential impact on human health.
Summary of Health Effects
The human body has several ways to process the ammonia it produces and is capable of clearing large levels of ammonia from its system.
• Ammonia levels in the air as low as 5 parts per million (ppm) can be recognized by odor. An average person detects ammonia by odor at around 17 ppm.
• According to the World Health Organization (WHO), continuous exposure to 25 ppm of ammonia in the air does not
result in a significant increase in blood levels of ammonia in the body.
• According to the Occupational Safety and Health Administration (OSHA), the least amount of ammonia which is found to be irritating to the eyes, nose and throat of the most sensitive individuals is 50 ppm.
• There is no evidence that ammonia causes cancer.
• There is no evidence that exposure to the levels of ammonia found in the environment causes birth defects or other
• Because ammonia is present in the human body at all times, no long-term health effects from inhalation exposure to low levels of ammonia would be expected.
• Because ammonia is a respiratory tract irritant, persons who are hyperreactive to other respiratory irritants, or who are
asthmatic, may be expected to be more susceptible to inhalation of high concentrations of ammonia.