Why is automobile exhaust harmful to human health?

Scientific analysis shows that automobile exhaust is mainly divided into gasoline exhaust and diesel exhaust. It contains hundreds of different compounds, and the main pollutants are solid suspended particles, carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides, lead and sulfur oxides. The harmful exhaust gas emitted by a car in a year is three times larger than its own weight. The British Association for Air Cleanliness and Environmental Protection has published a research report saying that compared with the victims of traffic accidents, the number of people who die from air pollution in Britain is 10 times more each year. Now, let's analyze the harmful substances in automobile exhaust.

1, solid suspended particles

The composition of solid suspended particles is very complex, and it has strong adsorption capacity, which can adsorb all kinds of metal dust, strong carcinogen benzopyrene and pathogenic microorganisms. Solid suspended particles enter the lungs with breathing, and stay in different parts of the respiratory tract through collision, diffusion and deposition, causing respiratory diseases. When suspended particles accumulate to a critical concentration, it will stimulate the formation of malignant tumors. In addition, suspended particles can also directly contact the skin and eyes, blocking the hair follicles and sweat glands of the skin, causing dermatitis and conjunctivitis, and even causing corneal damage.

2. Carbon monoxide

Carbon monoxide binds to hemoglobin in blood 250 times faster than oxygen. Carbon monoxide enters the blood circulation through the respiratory tract, and forms carboxyhemoglobin after affinity with hemoglobin, thus weakening the function of blood to deliver oxygen to various tissues, endangering the central nervous system, causing dysfunction such as sensation, reaction, understanding and memory, and even endangering the blood circulation system, leading to life-threatening. Therefore, even if a small amount of carbon monoxide is inhaled, it may cause terrible hypoxia damage to people.

3. Nitric oxide

Nitrogen oxides mainly refer to nitric oxide and nitrogen dioxide, which are harmful gases to human body, especially respiratory system. Exposure to air with nitrogen dioxide concentration of 9.4 mg/m3 10 minute can cause respiratory dysfunction.

4. Hydrocarbons

At present, its direct harm to human health is not clear. However, under the action of solar ultraviolet rays, nitrogen oxides and hydrocarbons will produce an irritating light blue smoke, which contains complex compounds such as ozone, aldehydes and nitrates. The most prominent harm of this photochemical smog to human body is to stimulate the eyes and upper respiratory mucosa, causing eye redness and laryngitis. 1952 65438+February, photochemical smog occurred in London, and the number of deaths in four days was 4,000 more than that in the same period of normal years, and the number of deaths over 45 years old was the highest, about three times as high as usual; /kloc-the number of people under the age of 0 is about twice as high as usual.

5. Lead

Lead is a toxic heavy metal element. Most automobile engine oils are mixed with explosion-proof agent tetraethyl lead or methyl lead, and the lead and its compounds produced after combustion are toxic substances. More than 60% of lead in urban air comes from the burning of leaded gasoline in automobiles. Excessive lead content in human body will cause cardiovascular diseases and affect the functions of important organs such as liver and kidney and nervous system. Because of the high ratio of lead to dust, it usually accumulates in the air at a height of about 1 m, so it poses the greatest threat to children.

6. dioxins

Dioxin, also known as dioxin (qǐ), is a colorless and odorless fat-soluble substance with serious toxicity. It is an environmental pollutant that poses a great threat to human health. It has strong carcinogenicity, can cause deformity, damage human immune function and male and female reproductive function, and is one of the most toxic compounds known in the world.