We all know that air pollution mostly refers to pollution caused by excessive suspended particulate matter, sulfur dioxide, nitrogen oxides, etc. in the air. However, in the past two years, a new term called " ozone pollution " has emerged in environmental and air quality monitoring. Does ozone also cause pollution?
Many friends know about ozone. This gas has a smell like fish (some people smell it like grass), hence the name. It has strong oxidizing properties, so it has a strong disinfection and sterilization effect, so we all I have heard of ozone disinfection or ozone decontamination, and some families use it to wash dishes. And many friends know that there is an ozone layer in the atmosphere, which can block ultraviolet rays in the sun and has a protective effect on human skin. Therefore, it is generally believed that ozone is a something beneficial.
However, according to a report by CCTV News on June 28, the China Environmental Monitoring Center jointly discussed with the regional air quality forecast centers and relevant provincial air quality forecast departments and found that from June 28 to July 2, many regions in my country ( Moderate ozone pollution may occur locally in the central and southern, northwest and southwest regions of Beijing-Tianjin-Hebei) or moderate ozone pollution may occur. Will ozone also cause pollution? How is this going?
Ozone is an allotrope of oxygen, and it is also a form of oxygen molecules that exists in nature. The chemical formula is O₃, and the formula weight is 47.998. Under normal conditions, it appears as a light blue gas. Ozone is stronger than oxygen Oxidants can produce oxidation reactions at lower temperatures. For example, they can oxidize silver to silver peroxide, lead sulfide to lead sulfate, and potassium iodide. 2016 If turpentine, gas, etc. are placed in ozone, it is likely to occur. Spontaneous combustion phenomenon, if ozone is dissolved in water, it will be a powerful bleaching agent, so ozone is actually used more often in daily life. In addition to acting as a strong oxidizing agent and bleaching agent, it can also be used to make hair deodorants, air purifiers for volatile organic compounds (VOCs), and automobile exhaust gas forming agents. In addition, it is also widely used in chemical production and can also be used as a hair deodorant. To be used as oxidizer for rocket fuel, etc.
In fact, the strong oxidizing property of ozone also shows that the human body cannot be exposed to too much of this kind of thing, otherwise oxygen poisoning reaction is likely to occur. Medical experiments have found that when the ozone concentration reaches a concentration of 200 micrograms per cubic meter (200μg/ m³): People's eyes, nose and throat will feel irritated; when the concentration reaches 1300 micrograms per cubic meter, the human body's lung air bubbles gas diffusion capacity will decrease significantly; when the concentration exceeds 2000 micrograms per cubic meter, the eyes and There is an acute burning sensation in the respiratory organs and central nervous system disorders. Long-term breathing (1 to 2 hours) will cause changes in lung cell proteins and a headache. When the concentration exceeds 4000 micrograms per cubic meter, breathing for a long time may be life-threatening. .
It can be seen that too high ozone concentration is harmful to the human body, so the environment and air monitoring department has set up an ozone pollution monitoring mechanism. So why is it said that ozone pollution may occur from June 28 to July 2? The main reason is that in summer, when the sun is strong and the temperature is high, ozone is more likely to be produced.
The main conditions for the generation of ozone are high light radiation intensity, high temperature, low humidity, poor atmospheric diffusion conditions, the existence of inversion phenomenon, etc. When ultraviolet rays in sunlight are irradiated onto oxygen molecules in the air, they can be It decomposes into two oxygen atoms and , and a single oxygen atom can combine with oxygen molecules in the air to form ozone molecules, so the ozone concentration will increase under strong light conditions. Therefore, the clearer the weather and the clearer the sky, the more serious this ozone pollution will tend to be.
In addition, volatile organic compounds VOC and nitrogen oxides formed from automobile exhaust will also catalyze the production of ozone under the combined action of high temperature and light radiation. Therefore, the highest peak of ozone concentration during the year is concentrated in summer, that is Because there are conditions that are conducive to the formation of ozone, such as strong sunshine, few clouds, and weak winds; and throughout the day, the concentration of ozone is the highest between 11 a.m. and 15 p.m., and then slowly decreases.
In fact, on June 21 this year, the China Environmental Monitoring Station, regional air quality forecasting centers and relevant provincial air quality forecasting departments jointly issued an ozone pollution forecast for June 21st to 25th, saying North China, northwest China, and the central and northern parts of East China will be sunny, hot and drier, and it is expected that a light to moderate ozone pollution process will occur. However, individual cities in central and southern North China are at risk of severe pollution. The large-scale rainfall from the 26th to the 28th will end this ozone pollution process. However, conditions for ozone production in the air were sufficient after the 28th, so the forecast was issued again. It can be seen that the clearer the weather is not the better the air quality! The conditions for the occurrence of ozone pollution are basically opposite to those of other types of air pollution.
So how to avoid the damage caused by ozone pollution? In fact, high concentrations of ozone mainly appear in outdoor environments with strong light, so you should try to reduce going out and outdoor activities when the light is strong during the day. If you must go out, you should enter the room as soon as possible, because the indoor ozone concentration will be 50% lower than outdoor. In addition, The elderly and children are more sensitive to ozone and should pay more attention to protection.
Reference:
"CCTV News" June 28 article "Ozone pollution weather may occur in Beijing, Tianjin and Hebei in the next five days"
