In recent years, air pollution has become more and more serious, and people's awareness of environmental protection has gradually increased. Haze has then attracted widespread attention, and most people are aware of the causes of PM2.5 exceedance: motor vehicle emissions, industrial pollution, coal-fired pollution, construction dust, and external pollution. Another important source of pollution that has been overlooked - ammonia pollution - is an important reason why the PM2.5 index is continuously pushed up.

NH3, is a colorless and transparent gas with irritating odor. It is extremely soluble in water and is an important raw material for the manufacture of fertilizers and explosives. Ammonia and acid reaction will produce ammonium sulfate, ammonium nitrate, these two ammonium salts also play a vital role in the formation of atmospheric haze particles, many scientists have also confirmed this view: heavy pollution weather, ammonium sulfate, ammonium nitrate, the sum of the mass of about 40%-60% of PM2.5, the more serious pollution, the higher the proportion.

Ammonia can also cause human poisoning, long-term exposure to ammonia, some people may develop skin pigmentation or finger ulcers and other symptoms; ammonia is exhaled into the lungs and easily enter the blood through the alveoli, combining with hemoglobin and destroying the oxygen transport function. Short-term inhalation of a large amount of ammonia may cause tears, sore throat, hoarseness, coughing, sputum with blood, chest tightness, breathing difficulties, may be accompanied by dizziness, headache, nausea, vomiting, weakness, etc. In severe cases, pulmonary edema, adult respiratory distress syndrome, and respiratory irritation symptoms may occur.

The use of ammonia sensors in industrial hazardous occasions to detect, protect staff safety production, widely used in petroleum, chemical, fire, gas, shipping, health epidemic prevention, environmental monitoring, energy and power, metallurgical casting and other fields, for the majority of enterprise units to protect the safety of production.