Hazards of air pollution The hazards of air pollution mainly include the following aspects:
(1) Harm to human health
People need to breathe air to keep alive. An adult breathes about 20,000 times a day and inhales 1.5 ~ 20 cubic meters of air. Therefore, polluted air has a direct impact on human health.
The harm of air pollutants to human body is various, mainly manifested in respiratory diseases and physiological dysfunction, as well as the irritation of mucosal tissues such as eyes and nose.
For example,1February 5-8, 952, the soot incident in London, England, killed 4000 people. People put
Soot incident
The smoke of this disaster is called "the smoke of killing". According to the analysis, this is because there was no wind and fog in London, and the smoke and dust generated by factory chimneys and residents' heating permeated the urban area of London for a long time. The highest concentration of smoke and dust reaches 4.46 mg/m3, and the daily average concentration of sulfur dioxide reaches 3.83 ml/m3. Sulfuric acid droplets produced by chemical reaction of sulfur dioxide attach to smoke or condense on fog droplets, and enter organs with breathing, which makes people sick or accelerates the death of patients with chronic diseases. This is also called photochemical pollution.
As can be seen from the above example, when the concentration of pollutants in the air is high, it will cause acute pollution poisoning, or aggravate the symptoms, and even kill thousands of people within a few days. In fact, even if the concentration of pollutants in the atmosphere is not high, breathing this polluted air all the year round will cause chronic bronchitis, bronchial asthma, emphysema, lung cancer and other diseases.
(2) Harm to plants
Air pollutants, especially sulfur dioxide and fluoride, are very harmful to plants. When the concentration of pollutants is high, it will cause acute damage to plants, damage to the surface of plant leaves, or directly cause leaves to wither and fall off; When the concentration of pollutants is not high, it will cause chronic damage to plants, make the leaves of plants fade, or have no harmful symptoms on the surface, but the physiological functions of plants are affected, leading to the decline of plant yield and deterioration of quality.
(3) Impact on weather and climate
The influence of air pollutants on weather and climate is very significant, which can be explained from the following aspects:
(1) Reduce the amount of solar radiation reaching the ground: A large number of smoke particles discharged into the atmosphere by factories, power stations, automobiles, household heating equipment, etc. make the air very turbid, which blocks the sunlight and reduces the amount of solar radiation reaching the ground. According to observation and statistics, in the days when smoke and dust are not scattered in large industrial cities, the direct sunlight on the ground is reduced by nearly 40% compared with the days without smoke and dust. In cities with serious air pollution, people, animals and plants will be stunted due to lack of sunshine every day.
② Increase atmospheric precipitation.
acid rain
Many particles emitted by large industrial cities have the function of condensation nuclei of water vapor. Therefore, when there are other precipitation conditions in the atmosphere, there will be precipitation weather. In the downwind areas of large industrial cities, there is more precipitation.
③ Acid rain: Sometimes, the rain falling from the sky contains sulfuric acid. This kind of acid rain is the oxidation of sulfur dioxide, a pollutant in the atmosphere, to form sulfuric acid, which falls with the precipitation in nature. Sulfuric acid rain can destroy large areas of forests and crops, corrode and destroy paper products, textiles and leather products, degrade metal antirust coatings and reduce their protective effects, and also corrode and pollute buildings.
(4) Raise the atmospheric temperature: Over large industrial cities, the air temperature near the ground is higher than that in the surrounding suburbs due to a large amount of waste heat discharged into the air. This phenomenon is called "heat island effect" in meteorology.
⑤ Impact on global climate: In recent years, people have gradually noticed the impact of air pollution on global climate change. After research, people think that carbon dioxide plays an important role in various air pollutants that may cause climate change. About 50% of the carbon dioxide released into the atmosphere by countless chimneys and other exhaust pipes on the earth remains in the atmosphere. Carbon dioxide can absorb long-wave radiation on the ground and raise the air temperature near the ground, which is the so-called "greenhouse effect". It is roughly estimated that the near-surface temperature will increase by 0.5 ~ 2℃ for every 25% increase of carbon dioxide content in the atmosphere. If 100% is increased, the near-surface temperature can be increased by 1.5 ~ 6℃. Some experts believe that the carbon dioxide content in the atmosphere will increase at the current rate, which will melt the ice in the North and South poles in a few years, leading to global climate anomalies.