The substances that affect our living environment are called environmental pollutants, environmental pollutants come from both natural and artificial. The causes of environmental pollution are roughly divided into chemical, physical, biological three types. The following is a brief introduction to environmental pollutants:
Dust
Dust is the most widely involved in the atmospheric environment, the most serious harm of a pollutant. Dust in the atmosphere is divided into two kinds of dust and dust fall. The so-called floating dust is the floating particles of dust particles below 10 microns, and the so-called precipitation dust refers to the pollutants in the atmosphere by their own weight and precipitation of the material.
Whether dust or precipitation dust, the atmospheric environment, temperature, climate, sunshine, visibility, human health, as well as animals and plants have an impact. Dust, especially 0.5-5 micron drift dust on the most harmful, because this kind of drift dust contains a variety of toxic metals or carcinogens, very easy to enter the human body with the breath, about half of them can be attached to the lung wall, constitute or aggravate the human body's respiratory tract diseases. According to the survey, drifting dust concentration of 100 μg / m 3, children's respiratory infections increased significantly; drifting dust concentration of 200 μg / m 3, chronic respiratory disease mortality increased; drifting dust concentration of 300 μg / m 3, respiratory disease acute deterioration; drifting dust concentration of 800 μg / m 3, respiratory diseases, heart disease mortality increased, traffic accidents serious. Therefore, the State has set the maximum allowable primary concentration of airborne dust in residential areas at 0.50 mg/m3 and the average daily concentration at 0.15 mg/m3.
Fluoride
Fluoride is often measured in the form of fluorine or hydrogen fluoride. In addition to local fluoride contaminated areas, fluoride is found in the air and drainage water of iron and steel mills, phosphate fertilizer plants, aluminum electrolysis plants, glass and ceramic plants, and fluoroplastic production plants.
Fluoride can be harmful to animals, plants and humans. The effect on plants is 10-100 times greater than sulfur dioxide, fluoride can accumulate in plants, when the concentration of fluoride reaches 50-100ppm, the plant leaf tissue will be necrotic. Livestock drinking water and feed with high fluoride content will cause lesions of teeth and bones. Fluoride on the human body to the extent of the harm than sulfur dioxide 20 times greater, mainly bone victimization, manifested in the limbs of the long bone pain, the heavy osteoporosis, osteomalacia or type of change, easy to occur spontaneous fracture; second damage to the skin, so that the skin itchy, painful, eczema and a variety of dermatitis.
So fluoride (replaced by hydrogen fluoride) in the atmosphere in residential areas in the highest permissible concentration of a determination of the plant for 0.02 mg/m3, the average daily concentration value of 0.007 mg/m3; workshop air the highest permissible concentration of hydrogen fluoride for 1 mg/m3; ground water the highest concentration of fluorine permissible for 1 mg/liter; drinking water fluorine concentration shall not exceed 1.0 mg/liter, the appropriate concentration is 0.5-1.0 mg/liter.
Chloride
Chloride in gas is mainly chlorine, hydrogen chloride; chloride in water is mainly hydrochloride.
Chlorine is a yellow-green toxic gas with a strong irritating odor. It is a strong oxidizer, and carbon dioxide to generate more toxic phosgene (COCL2). The specific gravity of chlorine gas is 2.49, so chlorine gas emissions or leakage is mainly along the ground sinking in the bottom of the air. Chlorine gas is the main source of chemical industry, light industry, non-ferrous metal smelting of chlorine roasting or chlorination volatilization process.
Chlorine gas irritates the eyes, nose, throat and upper respiratory tract and deep respiratory tract, through the respiratory tract and the mucous membranes of the skin to the harm. Mild poisoning, chest tightness, itchy throat, dry cough, eye stinging; depth of poisoning, elevated body temperature, and toxic pulmonary edema and even shock. Therefore, the maximum permissible concentration of chlorine in the atmosphere of the residential area once measured value of 0.1 mm / m 3, the daily average value of 0.03 mg / m 3.
Hydrogen chloride is a colorless gas with an irritating odor, mainly through the respiratory tract hazardous to human health. Long-term exposure to hydrogen chloride can cause laryngeal mucous membrane irritation, nasal mucous membrane ulcers, dental corrosion and gastrointestinal diseases. Hydrogen chloride gas also has serious corrosive effects on metals. Therefore, hydrogen chloride gas in the atmosphere in residential areas, the maximum allowable concentration of a measured value of 0.05 mg / m 3 daily average concentration of 0.15 mg / m 3.
Nitrogen oxides
Nitrogen oxides in the gas is colorless nitrogen oxides, reddish-brown nitrogen dioxide gas and its mixtures of the general term.
Nitrogen oxides are mainly harmful to the human body through the respiratory tract. Poisoning symptoms manifested as inflammation of the respiratory tract, cough, bronchitis, pneumonia and so on. Inhalation of high concentrations of nitrogen oxides can quickly appear asphyxiation, spasm and even death. Therefore, the maximum permissible concentration of nitrogen oxides (converted to nitrogen dioxide) in the atmosphere of the residents of a single determination of 0.15 mg/m3.
Carbon monoxide
Carbon monoxide is the product of incomplete combustion of carbon-containing substances. Of the gaseous pollutants in the air, carbon monoxide has the largest amount. Carbon monoxide, also known as gas, is a colorless, odorless and highly toxic gas.
Carbon monoxide enters the body through the respiratory tract and causes poisoning. After inhaling carbon monoxide, it enters the bloodstream through the lungs, and soon forms carbon dioxide hemoglobin, making hemoglobin lose the ability to transport oxygen, which leads to poisoning of the whole body tissues, especially the central nervous system, due to severe lack of oxygen. When carbon monoxide is 10ppm, it will cause chronic poisoning, when it is 100ppm, people will feel headache and nausea, and when it is 10,000ppm, people will die immediately. Mild poisoning by carbon monoxide will cause headache, nausea, vomiting, weakness of limbs, or temporary fainting. In moderate poisoning, in addition to worsening of the above symptoms, there is coma or collapse, and the skin and mucous membranes are cherry-colored. Severe poisoning will also occur sudden fainting, coma lasts for several hours, and complicated by myocardial damage and other symptoms.
The maximum permissible concentration of carbon monoxide in the atmosphere of a residential area is 3 mg/m3 in a single measurement, and the daily average value is 1 mg/m3.