What are the causes, preventive measures and hazards of smog?

Smog is caused by automobile exhaust, factory exhaust and fireworks.

When the suspended water vapor in the atmosphere condenses and the visibility is lower than 1000 meters, it is called fog in meteorology.

When the water vapor contained in the air reaches the maximum, saturation will occur. If the water vapor exceeds saturation, the excess will condense out and combine with tiny dust particles in the air to form small water droplets or ice crystals, which will be suspended in the air layer near the ground and become fog. The lower the temperature, the less water vapor can be contained in the air, and the easier it is to form smog.

In view of the specific meteorological conditions in Beijing, North China and other places, under the influence of low temperature, when the warm and humid southerly wind near the ground moves horizontally, it gradually cools down after passing through the cold ground or water surface to form fog.

PM2.5

In foggy weather, PM2.5 is the "culprit". There are many main sources. One is automobile exhaust. In recent years, there are more and more cars in cities, and the emission of automobile exhaust is also increasing, which contributes about 60% to PM2.5 in urban air. The second is road dust and construction dust. According to research, road dust is the main source of PM2.5, accounting for about 20% of the source of PM2.5, and the third is the secondary pollution produced by factories. Fourth, the pollutants emitted by low-altitude coal burning during heating in winter. Fifth, the flue gas generated by the burning of biomass (straw and firewood) and garbage incineration is also an important source of PM2.5

Non-diffusion of pollutants

Fog itself is not pollution, but the atmospheric environment that produces fog is in a relatively stable state, and pollutants in the air are not easy to spread outward, resulting in agglomeration effect, which will make pollution more and more serious. Similarly, under the conditions of low air pressure and low wind, the combination of urban pollutants and water vapor in the lower air will also aggravate the degree of smog. "

Meteorologists said that because the fog itself presents an uneven phenomenon. Therefore, there will be different degrees of smog in the same city.

The Central Meteorological Observatory predicts that the cold air activity in China will be weak in the next three to five days, and the central and eastern regions will still be in a foggy period. ?

But the foggy weather in these areas is intermittent. 14 ~ 15, there is a cold air activity in the north, and the haze weather in some areas will also be weakened. Throughout mid-June, there were relatively many foggy days in the central and eastern regions, with high incidence areas in North China Plain, Huanghuai area and Sichuan Basin.

Hazards of smog

According to experts, the smog seems mild, but in fact it contains more than 20 kinds of fine particles and toxic substances harmful to human body, including acids, alkalis, salts, amines and phenols. , as well as dust, pollen, mites, influenza virus, tuberculosis, pneumococcus, etc. Its content is dozens of times that of ordinary atmospheric water droplets. What effects will heavy fog have on human health?

Major danger?

Winter fog is called "winter killer", and pollutants such as industrial waste gas, automobile exhaust, dust in the air, bacteria and viruses in the air attach to these water droplets. In people's daily life and travel, these substances will have an impact on the human respiratory tract, which may cause acute upper respiratory tract infection (cold), acute tracheobronchitis, pneumonia and asthma attacks, and induce or aggravate chronic bronchitis. In particular, children's respiratory mucosa of nose, trachea and bronchus is tender, and the number of alveoli is small, the development of elastic fibers is poor, and the interstitial development is vigorous, which makes them more susceptible to respiratory viruses. Being in foggy weather for a long time will cause tracheitis, laryngitis, pneumonia, asthma, rhinitis, conjunctivitis, allergic diseases, etc., which will have a certain impact on the growth and physique of children and adolescents. In addition, diabetic patients with poor air quality and poor resistance in foggy days are very likely to have lung and trachea infections, which will aggravate their condition.

1. Effects on respiratory system.

The composition of smog is very complex, including hundreds of atmospheric chemical particles. Among them, aerosol particles smaller than 10 micron are harmful to health, such as mineral particles, sea salt, sulfate, nitrate, organic aerosol particles, fuel, automobile exhaust, etc., which can directly enter and adhere to human respiratory tract and alveoli. In particular, submicron particles will be deposited in the upper and lower respiratory tract and alveoli respectively, causing acute rhinitis and acute bronchitis. For patients with chronic respiratory diseases such as bronchial asthma, chronic bronchitis, obstructive emphysema, and chronic obstructive pulmonary disease, smog weather will make the condition acute or acute. Staying in this environment for a long time will also induce lung cancer.

2. Influence on cardiovascular system.

Haze weather also has a serious impact on cardiovascular and cerebrovascular diseases, which will hinder normal blood circulation and lead to cardiovascular diseases, hypertension, coronary heart disease, cerebral hemorrhage, angina pectoris, myocardial infarction, heart failure, etc., leading to chronic bronchitis.

Pulmonary heart disease and so on. In addition, when the air pressure is relatively low in foggy weather, people will feel irritable and their blood pressure will naturally rise. On the other hand, in foggy days, the temperature is often low. Some patients with hypertension and coronary heart disease suddenly go from warm indoor to cold outdoor, and blood vessels expand with heat and contract with cold, which will also increase blood pressure, leading to stroke and myocardial infarction. Therefore, patients with cardiovascular and cerebrovascular diseases must take medicine on time and handle it carefully.

3. Hazy weather will also lead to the weakening of ultraviolet rays in the surface layer, which can enhance the activity of infectious bacteria in the air and increase infectious diseases.

4. It is not conducive to children's growth.

In foggy days, due to the decrease of sunshine, insufficient ultraviolet radiation for children, insufficient production of vitamin D in the body, and greatly reduced absorption of calcium, rickets in infants and young children will be seriously caused, which will slow down the growth and development of children.

5. Affect mental health.

Experts point out that continuous foggy days have an impact on people's psychology and body. Psychologically speaking, foggy days will give people a feeling of depression, which will stimulate or aggravate the state of psychological depression. In addition, due to the weak light and low air pressure in foggy days, some people will feel lazy and depressed in foggy days.

6. Affect reproductive capacity.

20 13 1 1.5 China academy of social sciences and China meteorological bureau jointly issued the "green paper on climate change: report on coping with climate change (20 13)" (hereinafter referred to as Green Book), pointing out that the smog weather in China has generally increased in recent 50 years. Among them, the number of foggy days decreased significantly, the number of haze days increased significantly, and the process of persistent haze increased significantly. [1] Smog weather will have a significant negative impact on climate, environment, health and economy, such as acid rain and photochemical smog in urban atmosphere, which will reduce atmospheric visibility and hinder the communication between air, water and land. Increase mortality, aggravate chronic diseases, aggravate respiratory and heart diseases, change lung function and structure, affect reproductive capacity and change human immune structure.

Hazy weather is more likely to cause cancer.

Zhong Nanshan, academician of China Academy of Engineering and director of Guangzhou Institute of Respiratory Diseases, once pointed out at a forum that in the past 30 years, the smoking rate of the public in China has been declining, but the prevalence of lung cancer has increased more than four times. This may be related to the increase in haze days. Not only foggy days with very low visibility will have an impact on human health, but also foggy days and cloudy days will have the same problem.

How to prevent it

Wear a mask?

Medical masks can block 95% of 0.3 micron particles. When choosing a mask, you should buy a regular and qualified mask, wear it at the same time, buy a model that matches your face size, and stick it on your skin to the greatest extent, so that polluted particles can't get in. The mask cannot be washed. After you take it off, you should wait until it is dry before folding it, so as to prevent the breathing moisture from breeding bacteria on the mask. The elderly and patients with cardiovascular diseases should avoid wearing it, because it is a professional anti-virus aerosol mask with good sealing performance, and it is easy to breathe and feel dizzy after wearing it.

Try not to ride a bike when you go out?

Smog can temporarily reduce morning exercises and try to 10- 14 go out. At the same time, drink more water, smoke less, stay away from "second-hand smoke" and reduce the burden on organs such as lungs and liver. People who are used to riding bicycles and electric cars to work or going out for business should try to avoid the morning and evening rush hours of traffic jams and try to transfer to buses. This is because many chemical components in automobile exhaust are not completely burned and will float with fine particles in the air. When you ride a bike or an electric car, your body needs oxygen, and your lungs will inhale a lot of air.

When you enter the room, there are three things you must do?

The cleaning method is simple. Do three things well: wash your face, rinse your mouth and clear your nose. It is best to wash your face with warm water, which can effectively clean the smog particles attached to the skin; The purpose of gargling is to remove dirt attached to the mouth; The key is to clean the nasal cavity. When cleaning the nasal cavity, be sure to absorb water gently to avoid choking. When cleaning the child's nasal cavity, parents can repeatedly wash the clean cotton swab with water.

Patients should go out less?

In this weather, reducing going out is the most effective way to protect yourself, especially for people with cardiovascular and cerebrovascular diseases and respiratory diseases. According to this study, when the fog concentration increases 103 μ g/m3, the risk of excess death from all causes of residents increases by 2.29\%, and the lag time is 1-2 days after excluding the influencing factors such as age, gender, time effect and meteorological factors. The risk of excess death caused by cardiovascular and cerebrovascular diseases is high, which is 3.08%.

Try not to open the window in foggy weather?

Try not to open the window when the foggy weather escalates; If you really need to open the window for ventilation, try to avoid the morning and evening smog peak hours when opening the window. You can open a crack in the window to prevent the wind from blowing in directly, and the ventilation time should be half an hour to one hour at a time. Residents who use air conditioning for heating should pay special attention to opening windows to ensure adequate indoor oxygen.

Eat more foods that clear and moisten the lungs.

Lily is the first choice, which has the effects of moistening lung and relieving cough, nourishing yin and clearing heat, clearing heart and calming nerves; Lung-clearing food, such as carrot, pear, fungus, soybean milk, honey, grape, jujube, pomegranate, orange, sugarcane, pestle, lily, radish, water chestnut, tremella, etc.