What is ammonia?

Ammonia (NH3) is a corrosive, colorless gas with a distinctive, pungent odor. Commonly found in nature, ammonia can also be stored as a liquid at high pressure and is easily soluble in water. Ammonia deposits itself in wet and dry forms on land, plants, soils, and water.

Chemically, ammonia is NH3 when un-ionized and NH4+ when ionized.

Ammonia is an air pollutant and a secondary particulate precursor. It combines with other compounds in the atmosphere like nitric and sulphate acids to form ammonium salts, a harmful form of fine particulate matter.1

Where does it come from?

Ammonia comes from both natural and man-made sources. Natural sources include:

  • decaying organic matter 
  • human and animal waste 

Man-made sources of ammonia include:

  • fertilizer manufacturing
  • industrial processes
  • waste disposal sites 

Agriculture produces a great deal of ammonia pollution through both animal waste and fertilizer manufacturing and use. The majority of airborne ammonia comes from fertilizer, some of which is carried from inland farms to nearby cities. 

A 2017 paper published in Geophysical Research Letters identified numerous atmospheric ammonia hotspots generated through farming and animal husbandry. 2 The most intense hotspots identified included: 

  • The American Midwest
  • Central Europe
  • Western Europe
  • Central Africa
  • West Africa
  • Siberia
  • Central Asia
  • East Asia
  • South Asia
  • Southeast Asia 

The causes behind ammonia hotspots can vary by region. In the American Midwest, NH3 production may result from increasing temperatures and improved regulations of sulfur dioxide (SO2) and nitrogen oxides, which occurred due to acid rain reduction efforts. 

In South Asia, levels of atmospheric ammonia are often eclipsed by increases in SO2 and nitrogen oxides.

What is ammonia used for?

In addition to being a pollutant, ammonia is an essential nitrogen-containing nutrient produced by plant and animal decomposition as well as being excreted by animals. Ammonia can then be converted to nitrite (NO2) and nitrate (NO3) by bacteria. At this point, ammonia has been converted into a nutrient for plants.

Because of ammonia’s nitrogen-containing properties, 90 percent of commercially produced ammonia is used in fertilizer. Ammonia can also be used on its own or as an ingredient in household cleaning products, where it is effective at removing vegetable oil and animal fat stains.

Other commercial uses for ammonia include: 3

  • plastics
  • fabrics
  • pharmaceuticals
  • dyes
  • pesticides
  • explosives manufacturing
  • nitrogen stabilizer
  • water purification
  • refrigerant in air-conditioners

How does ammonia affect human health?

Exposure to high concentrations of ammonia in the environment can cause irritation to eyes, nose and throat as well as skin.

Long-term health concerns related to ammonia exposure include:

  • severe cardiovascular and respiratory effects
  • decreased lung function
  • asthma aggravation
  • premature death

In August 2020, 78 people died from an ammonium nitrate blast in Beirut, Lebanon. A storage facility holding ammonium nitrate in small fertilizer pellets exploded near the cargo port while a major fire burned nearby. Though it is not certain the fire caused the explosion, the intensity of the nearby fire may have set off the explosion.4

Ammonia also contributes to the formation of harmful PM2.5. According to a 2011 technical note published in the Journal of Dairy Science, ammonia can form particulates in the atmosphere through chemical reactions with sulfuric and nitric acids. 5 Ammonia produced by livestock operations alone may contribute 5 percent to 20 percent of atmospheric PM2.5 in the United States on average, depending on the region and time of year. 

Serious health risks associated with PM2.5, short-term impacts, such as: 

  • burning of the nose, throat, and respiratory tract
  • fatigue
  • coughing
  • nose and throat irritation6

What are the environmental effects of ammonia?

Ammonia can contribute to the environmentally damaging processes of soil acidification and eutrophication of water bodies. Ammonia and nitrogen deposits from ammonia emissions harm biodiversity by encouraging species adapted to high nutrient-fueled growth to outcompete other species. This may lead to extinctions and changes to habitats.7

Wetland lichen and mosses can be damaged by minimal ammonia exposure, while grasslands and forests are also vulnerable. 

Ammonia in vehicle tailpipe emissions, when combined with nitrogen and sulfur compounds, contributes to smog in major cities. A 2017 paper published in the journal Environmental Science and Technology found that urban vehicle emissions in the American cities of Denver, Houston, and Philadelphia and in the Chinese cities of Baoding, Beijing, and Shijiazhuang were the largest contributors to local smog in those cities.8

Ammonia is co-emitted with nitrogen oxides, creating brown-colored ammonium nitrate. Though farms are a major source of ammonia emissions, smog in cities like Salt Lake City and those studied in the paper can be problematic even in winter when fertilizer is used at much lower levels than during peak agricultural seasons. Three quarters of PM2.5 particles found in the air in Salt Lake City’s 2017 winter were found to be ammonia nitrate.9

What can be done about ammonia in my environment?

People are regularly exposed to naturally-occurring ammonia found in the air, soil, and water. It’s regularly found in rainwater. Near hazardous waste sites, it can be found at dangerous levels attached to soil particles, in bodies of water, and as a gas in the air. Though ammonia doesn’t last long in the environment, it can linger in the air for up to a week.10

It’s easy to smell ammonia given its strong odor. People often associate the smell with household cleaners like window cleaners and floor waxes.

Airborne ammonia and ammonia compounds can be filtered out of rooms with air purifiers designed to specifically filter airborne ammonia, such as the GC AM

What are other air pollutants that affect your air quality?

There are many pollutants that can be monitored to help increase understanding of specific air quality issues, including:

The Clean Air Act regulates six criteria of air pollutants in the United States:11 

  • carbon monoxide
  • lead
  •  nitrogen oxides
  • ground-level ozone
  • particulate matter
  • sulphur dioxides 

Even though there have been improvements made to air quality through regulation, the world’s cities struggle with air pollution’s human and financial costs. Check out our Cost of Air Pollution counter and learn how clean air can help preserve health and life while alleviating harm to the global economy.