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Morning ladies and gentlemen，it is a great honor for me to be here to do my presentation, today I want to say something about air pollution-PM2.5. As the beginning of my presentation, I’ll show several pictures of foggy cities. Can you guess where is this picture taken from? Yes, it’s the Oriental Pearl in Shanghai. And this place is the Palace Museum in Beijing. This picture is no better than the former two. Ok, let’s come back to my theme. There’re four parts in my presentation. First I will introduce something of PM2.5. Then I’ll tell you how PM2.5 does harm to us, and what we can do to protect us from it. The last but the most important is what we need do to control the pollution. Do you know how small the PM2.5 is? Look at this picture, this is the fine beach sand, its diameter is about 90 micrometers, this is a piece of human hair, the blue ball is PM10, and the red ball is PM2.5.From the picture, we can draw the conclusion that, the diameter of PM10 is one fifth of hair’s, PM2.5 is one forth of PM10, then you can imagine how small the PM2.5 is. So scientists usually use PM2.5 to show the content of particulate in per cubic meter of air. The higher the index is, the more harmful to people. This map shows the PM2.5 all over the world, on the map, the heaviest polluted areas are located in the northeast part of China. If you want to know more about the details, look at this map. Unfortunately, Jinan is listed as one of the heaviest polluted cities in China. Then where is PM2.5 from? I think there are 4 main resources.●Daily power generation●Industrial production●Automotive exhaust emission●Dust on the construction sitesHow does PM2.5 dose harm to us? It does harm to our respiratory system and cardiovascular system. If you are exposed in high density of PM2.5, that may cause DNA damage and increase the risk of lung cancer. So when it comes to protection, we should wear PM2.5 mouth-muffle, chooses public transport, smoke less or don’t smoke, and don’t exercise in fog day morning.To reduce the density of PM2.5, the fundamental measures are as follows:●Control the pollution source●Planting●Using the monitoring network●Setting spray equipmentI hope that in 10 years,20 years, our sky will be like this. Thank you for your attention~Q：如果没有人为的空气污染，那么在空气中的PM2.5浓度是多少啊If there is no pollution, what is the concentration of PM2.5A：即使没有人为污染，空气中也有一定浓度的PM2.5.这个浓度称为背景浓度。
Hello，everyoneGood morning！My name is Xiao Weihong,I’m from Sichuan province.And today,my topic is Fog and haze.This is my name,and this is my student number.From this you can know that my topic is about 5 parts,and now,we look at the first part--Definition.Long long ago,we climb with our hands,as time goes by,We are walking upright.But the environment turns bad,we live in a world which is full of poison.In recent years, air pollution has already become one of the biggest environmental problems in China. Thick haze has blown off the coastal areas.So,what is haze?It’s a combination of little drops of water and tiny particles. For better understanding of this noun.Now,we should know another word--PM.It means particulate matter.It also means a small discrete[dɪ'skrit](离散的) mass of solid or liquid matter.So,we can easily know what is PM2.5.It means particles can be drawn into lung[lʌŋ], which diameter is less than 2.5 micron.We often pay our attention to PM2.5，because the number of 2.5 is very important ,if the diameter of particle is bigger than 2.5 micron,it will be stopped by our nose and will not go into our lung. But ifthe size of particle is less than 2.5 micron.It harms us most.So, wether['wɛðɚ] our weather['wɛðɚ] is good is determined by the number of PM2.5.Look at this picture,if the number of PM2.5 of per unit volume is less than 50,we say the air quality is good.if the number is between 50 to 100,we say the air quality is moderate.But if the number is between 151 to 200,we call it unhealthy.and if the number is above 300,we think it horrible.As we know,many places of China is even above 400.So,it’s very dangerous.Now,let’s look a historical event.London smog!Let’s know about it.First,we watch a short video.(I don’t know wether the computer can paly it) Ok,from this short video we can see a black world full of smog.So,what happened in London?In 1952, London smog happened,and it lead to 12000 people died directly or indirectly.In 1954 ,London launched a special act of pollution.After 4 years later,smog happened again,and 1200 people dead.Only after 1965,the toxic smoke was vanished.In 1968,Britain enacted the Clean Air Act.And until 1980, the fog day has been reduced to five days one year.It took about 30 years to solve the problem.So,from this accident,we know thatonce the fog happened, it will be hard to solve it.How about our situation?First,Let’s look some pictures.There’re two contrast figures.The upper left corner is a picture of beautiful scenery,it’s clear,but the one at the lower left corner looks terrible.And the top right one is the map of our country which looks pretty,but from this one we can see nothing except haze.How about this one?Oh,it’s a man who wears a respirator['rɛspəretɚ] is riding a bike in the endless smog.And again,this picture tells us a man is riding a bike in the road.It’s dangerous because it’s hard to see far. The last one,it looks beautiful in some degree.But like mushrooms,the more beautiful the more toxic it is.In fact,it’s very terrible.So,what caused our country to be this situation ?These several reasons are we recognized.First,burning of fossil fuels in vehicles.As we know,the number of cars in our country is increased rapidly.so ,the demand of fossil fuels is increased fast,too .Second,in our country the power plants still rely on fossil fuels. It contributes to air pollution mostly.Third,various industrial processes are existed everywhere.Their emissions of waste polluted the air.Therefore,it’s time to take some measures to change the situation .So, what should our government do? Firstly,our government should strengthen air monitor to know the the actual situation.Secondly, government should enact more strict laws and regulations in order to reduce the sources of pollution.Thirdly,government should regulate people 's daily action and the industrial stly,our country should help develop green and energy-saving energy.Only do these can our country become beautiful again.For an individual,what should we do to reduce the harm of haze?First,if conditions permit,we can wear a respirator which can help us perhaps not much.Second,if we go out ,we should try to take public transportation.Third,hybrid['haɪbrɪd] cars should be regarded. Four,clean energy should be promoted in our daily life.In the last,the public supervision is important. Not only the role of government, but must have the personal effort.Only do this can we have a better tomorrow.So let’s do something from now on.=============================================== =============Thank you,yes,it dose harm our body.as i have saidbefore,the PM2.5 will go into our lung though our respiratory['rɛspərətɔri] tract.Long-term effects can damage respiratory defenses.Particles can cause the loss of the body's immune function.Thank you!yes ,this is a question that we all care about.But as i said before,the haze is the result of long-term development.and I think it will not disappear totally in recent years.But if our government take more actions on the problem,it will be vanished faster than we expect.1.As you have said that we live in a world of haze ,will it cause any harm to our body?2.when do you think the haze will be vanished?。
