At least 137 people have been killed and about 5000 injured in a violent explosion in the port area of Beirut, the capital of Lebanon, on the evening of April 4. The government of Lebanon held an emergency meeting on the 5th local time to declare Beirut a disaster stricken city. A two-week state of emergency will be implemented in Beirut under the supervision of the military. According to the preliminary investigation by the government of Lebanon, the cause of the explosion was a batch of chemical materials in Beirut port. Lebanon’s prime minister Hassan diab said 2750 tons of ammonium nitrate had been stored in a container in a port warehouse for six years without security measures. For the specific cause of the explosion, some media reports said that it may be related to the spark spatter of welding operation near the container. In an interview with China News Agency, Zhao Haibo, general layout planning expert of Northeast Refining and Chemical Engineering Co., Ltd. of CNPC, said that ammonium nitrate is a common chemical fertilizer and chemical raw material, which is extremely insensitive explosive. It is stable at normal temperature and is not sensitive to impact, collision or friction. However, ammonium nitrate can form a very strong explosive mixture with any combustible solid. At the same time, the decomposition of ammonium nitrate will be intensified after heating, releasing reddish brown nitrogen oxide gas and oxygen. This decomposition is very easy to cause explosion, and “it is easy to explode, and it is difficult to clean up”. Zhao Haibo said that due to the characteristics of ammonium nitrate, safety regulations must be strictly observed in the process of production, storage, transportation and use of ammonium nitrate, such as storing it in a special warehouse, and it is strictly forbidden to bring other articles that are easy to cause combustion and explosion into the warehouse area. Marwan abd, the governor of Beirut, said that the economic losses caused by the explosion in Beirut port may be as high as US $10 billion to US $15 billion, and about 5000 people were killed or injured, according to Arabia television on the 5th. < / P > < p > why was the explosion so severe? According to Zhao Haibo, according to the calculation of the parameters of ammonium nitrate explosive and explosion heat, it is found that the power of the 2700 tons of ammonium nitrate is equivalent to 2400 tons in theory. In addition, the complex situation at the explosion site leads to chain reaction and increases secondary damage. “It is estimated that the life of the personnel within 900 meters from the explosion source is in danger, the personnel within 1300 meters from the explosion source are seriously injured or slightly injured, and the buildings within 900 meters from the explosion source will be damaged to varying degrees.” Zhao Haibo also reminded that a large number of toxic gases and dust containing nitrogen oxides will be produced after severe explosion, and people’s respiratory tract is easy to be damaged, such as chest tightness, shortness of breath, cough and other symptoms, and even lead to pneumothorax and emphysema. In addition to the direct consequences of the explosion, the impact of this catastrophic incident in the capital on the economy and society of Lebanon has also attracted much attention. Ding long, a professor at the National Institute of opening up at the University of international business and economic cooperation, told China news agency that Lebanon was once the economic and financial center of the Middle East, with banking, shipping, tourism, education and press and publishing industries among the top in the Middle East. However, after 15 years of civil war, its dominant position has been basically lost, coupled with the serious deterioration of the economic situation in recent years and the heavy debt burden, the domestic people’s livelihood is difficult. < / P > < p > “the explosion has made the economy of Lebanon worse.” Ding long said, “Lebanon has nearly lost its ability to help itself. I’m afraid it will be difficult to tide over the difficulties without the assistance of the international community this time.” According to Ding Long’s specific analysis, firstly, there are many ethnic groups and religious sects in Lebanon, and the national governance and government capacity are seriously insufficient. The port explosion may aggravate this political tension and lead to further social unrest; < / P > < p > secondly, as one of the most important economic sources of Lebanon, Beirut port was destroyed and closed, and necessary daily necessities were transported In addition, the warehouse near the explosion port stored the main vaccines and drugs in Lebanon. Hundreds of thousands of medicines inside were supposed to be supplied to medical centers in Lebanon. The explosion caused a huge blow to the hospital system, which was facing the severe challenge of the new epidemic situation. All these will be the problems that Lebanon will face in the post disaster reconstruction period. < p > < p > according to media reports, after the big explosion in the port area, Lebanon said it had decided to allocate 100 billion Lebanon pounds of emergency funds to deal with the subsequent impact of the explosion. At the same time, the government urged relevant departments to take measures to help the victims, including opening schools, hotels and other places to the homeless, and ensuring the supply of materials for people’s livelihood. At the same time, two French military aircraft carrying 55 people, about 15 tons of equipment and a mobile medical center arrived at Beirut airport on May 5; a plane carrying medical supplies from Qatar also arrived in Beirut on the same day; Iran and Cyprus sent medical teams or search and rescue teams to Lebanon; Russia will deploy a mobile hospital equipped with doctors in Beirut, In addition, Iraq and Kuwait plan to provide medical assistance, including field hospitals and materials, to Beirut. China’s 18th peacekeeping medical team to Lebanon has also deployed 9 medical personnel to form the “Beirut explosion” emergency medical team, which will carry drugs, consumables, protective equipment and other materials to Beirut. In addition, a number of countries, including the United States, the United Kingdom, Israel and Greece, have indicated that they will provide assistance to help Lebanon tide over the difficulties as soon as possible.