Ammonia (NH₃) is a pungent-smelling, colourless and toxic gas. It irritates the eyes and respiratory tract and has a suffocating effect. Ammonia is one of the most widely produced industrial chemicals. In nature, urea and various salts occur as reaction products.
Ammonia has an irritating effect on the eyes and respiratory organs at low concentrations, at high concentrations it is even corrosive and there is a danger to life.
The irritant effect already occurs at a concentration of 200 ppm (parts per million). This manifests itself as coughing and irritation of the nose and throat.
Above 1500 ppm, the gas is very harmful or even lethal to humans.
At a level of 16-27 % in the ambient air, there is also a risk of explosion.
The largest quantities of ammonia are released in industrialised countries in agriculture, because ammonia serves as a raw material for many fertilisers. As a result, ammonia spreads through the air and binds to particles and pollutants in the air - creating particulates.
Ammonia also forms the chemical basis for many other substances. For example, for the production of plastics and synthetic fibres, solvents and surface finishing agents. Therefore, ammonia vapours are also very often found indoors.
In the ambient air, the amount of ammonia varies depending on the spatial proximity to industry and agriculture. On average, it is below the recommended concentration of 1 ppm.
The odour threshold for ammonia in humans is 1 - 5 mg/m³ (= 0.16-0.84 ppm). High concentrations around 100 ppm are perceived as so unpleasant that panic-like reactions are the rule. The occupational exposure limit (OEL) is 14 mg/m³ (= 20 ppm).
Ammonia causes severe burns to the skin, eyes and respiratory tract. Coughing, nausea, headache, olfactory disturbance and increased salivation may be signs of excessive ammonia concentration.
A contact time of more than 15 min already poses a high risk to the skin. Damage to the eyes, immune system and gastrointestinal tract can also occur through prolonged exposure.
As protection, it is recommended to ventilate rooms in which ammonia gases are used regularly so that no oxygen deficiency or dangerous gas concentrations can occur.
Ammonia occurs naturally as a free gas only in small quantities. It is mainly formed during the decomposition of plants and excrement. Ammonia also occurs in very small quantities on the skin and in the stomach of humans: here as a metabolic product of bacteria.
As a starting material for many chemical compounds, ammonia is produced industrially on a large scale. For this purpose, it is extracted from the elements nitrogen and hydrogen under high pressure and at high temperatures (Haber-Bosch process): in 2017, for example, 150 million tonnes worldwide.
Ammonia is measured in the air-Q by means of an electrochemical sensor. NH₃ molecules "dock" on the surface of the sensor and cause a measurable current. The ammonia sensor we have chosen has a very high accuracy. The disadvantage of all electrochemical sensors is cross-sensitivity. The only known cross-sensitivity of the NH₃ sensor is hydrogen sulphide: if H₂S is present, an NH₃ increase is also indicated.
Measure ammonia and other gases and pollutants in indoor air in real time with the air-Q air analyser. The ammonia sensor can be ordered in the shop.