Concept discrimination
Heavily polluted weather conditions
The heavily polluted weather condition PM is called particulate matter in English. Scientists use PM2.5 to represent each kind.
The higher the content of this particulate matter per cubic meter of air, the more serious the air pollution.
Inhalable particulate matter and total suspended particulate matter in daily or weekly reports of urban air quality are two common air pollutants.
Inhalable particulate matter, also known as PM 10, refers to particulate matter with a diameter greater than 2.5 microns and equal to or less than 10 microns, which can enter the human respiratory system; The total suspended particulate matter is also called PM 100, that is, particles with a diameter less than or equal to 100 micron.
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particle source
The main source of PM2.5 is the residue discharged from combustion during daily power generation, industrial production and automobile exhaust emission, most of which contain toxic substances such as heavy metals.
Generally speaking, coarse particles with a particle size of 2.5 microns to 10 microns mainly come from road dust; Fine particulate matter (PM2.5) below 2.5 microns mainly comes from the combustion of fossil fuels (such as automobile exhaust and coal burning) and volatile organic compounds.
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Trait injury
Health damage
Meteorologists and medical experts believe that smog weather caused by fine particles is even more harmful to human health than sandstorms. Particles with a particle size larger than 10 micron will be blocked outside the human nose; Particles with a particle size of 2.5 microns to 10 microns can enter the upper respiratory tract, but some of them can be excreted through sputum and blocked by villi inside the nasal cavity, which is relatively harmless to human health; However, fine particles with a particle size below 2.5 microns have a diameter equivalent to that of human hair110, and are not easy to be stopped. Inhalation into the human body will directly enter the bronchus, interfere with the gas exchange in the lungs, and cause diseases including asthma, bronchitis and cardiovascular diseases.
These particles can also enter the blood through bronchi and alveoli, and harmful gases and heavy metals are dissolved in the blood, which is more harmful to human health. In EU countries, PM2.5 has reduced people's average life expectancy by 8.6 months. PM2.5 can also be a carrier of viruses and bacteria, which contributes to the spread of respiratory infectious diseases.
Wei Ye, an academician of China Academy of Engineering and former chief engineer of China National Environmental Monitoring Center, also studied that the higher the concentrations of PM2.5 and PM 10, the higher the incidence of respiratory diseases among children and their parents, especially the impact of PM2.5.
Experimental demonstration
A new discovery by Pan Xiaochuan, a professor at peking university health science center School of Public Health, and his colleagues was published in the journal Total Environmental Science. During the period of 2004-2006, the daily average concentration of PM2.5 in observation points on the campus of Peking University increased, and the number of emergency patients with cardiovascular diseases in the Third Hospital of Peking University about 4 kilometers away also increased. Although PM 10 and PM2.5 are both risk factors for cardiovascular diseases, the influence of PM2.5 is obviously greater.
The World Health Organization also pointed out in the 2005 edition of the Air Quality Guide that when the average annual concentration of PM2.5 reaches 35 μ g/m3, compared with the situation of 10 μ g/m3, the risk of human death will increase by about 15%. According to the report of the United Nations Environment Programme, if the concentration of PM2.5 per cubic meter increases by 20 mg, about 340,000 people will die in China and India every year.
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Monitor the situation
Monitoring standard
The standard of PM2.5 was put forward by the United States in 1997, which is mainly to monitor the fine particles that appear with the increasingly developed industrialization and are ignored in the old standard and harmful to human health. The PM2.5 index has become an important indicator to measure and control the degree of air pollution.
By the end of 20 10, except that some countries in the United States and the European Union have included PM2.5 in the national standard and imposed mandatory restrictions, most countries in the world have not carried out monitoring of PM2.5, and most countries generally monitor PM 10.
20 10 September, the national aeronautics and space administration (NASA) released the global air quality map, which specifically showed the density of PM2.5 around the world.
Global air quality map
map
The map of global air quality was produced by two researchers from Dalhousie University in Canada. According to two NASA satellites,
According to the monitoring results of the star monitor, the map of the average value of PM 2.5 from 20065438+0 to 2006 was drawn. In this picture, red (that is, the highest density of PM2.5) appears in North Africa, East Asia and China. The density and index of PM2.5 in North China, East China and Central China are even close to 80 μ g/m3, even exceeding the Sahara desert.
On this map of the global average air pollution situation from 20065438+0 to 2006, the regions with the highest PM2.5 in the world are all in North Africa and North China, East China and Central China of China.
The World Health Organization (WHO) believes that PM2.5 less than 10 is a safe value, while all these areas in China are above 50, close to 80, which is much higher than that in the Sahara desert.
The situation in China
According to the Evaluation Report of Urban Air Quality Information Openness Index (AQTI) issued by Law School of Renmin University of China and Center for Public Environmental Research (IPE) 20110, 20 domestic evaluation cities such as Beijing, Shanghai, Guangzhou and Chongqing have not carried out fine particle monitoring. It is worth noting that the pollution levels in international cities such as London, Paris and new york, which regularly monitor and release PM2.5, are relatively low. At the same time, many large cities in developing countries, such as Mexico City and New Delhi, have already carried out frequent monitoring and release of PM2.5.
From 20 1 1, 1 and 1, the Gravimetric Measurement of Ambient Air PM 10 and PM2.5 (hereinafter referred to as "Measurement") issued by the Ministry of Environmental Protection began to be implemented. This measurement standardized the measurement of PM2.5 for the first time, but in the Environmental Air Quality Standard recently revised by the Ministry of Environmental Protection, PM2.5 was not included in the mandatory monitoring index. [ 1]
2011110 Zhang Lijun, vice minister of environmental protection, said at the 7th international symposium on regional air quality management that China's atmospheric environmental quality standard of PM2.5 will be issued soon. The standard will use the value of the first transition period specified by the World Health Organization (WHO) to illustrate the pollution situation of the PM2.5 index.
Air quality in Beijing
be in danger of
The air quality in Beijing is harmful.
201115 Zhang, a famous atmospheric environmental expert and dean of Peking University Institute of Environmental Science and Engineering, revealed that the WHO standard is slightly looser than the American standard. Even according to WHO standards, after joining PM2.5, the number of cities in China that meet the air quality standards will drop from the current 80% to 20%. [2]
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Governance strategy
Air pollution and climate change need to be dealt with in a unified way, not separately. Because air pollution and climate change have a common cause to a great extent, that is, they are mainly caused by emissions from fossil fuel combustion, so reducing and controlling air pollution and reducing greenhouse gas emissions to protect the climate should be consistent in action. Some studies have pointed out that the increase of atmospheric aerosols reduces the amount of solar radiation reaching the ground, which is contrary to the warming effect of greenhouse gases and offsets each other. 50% of the surface warming caused by greenhouse gases may be offset by the cooling effect of aerosols. Once the aerosol is removed, the warming caused by greenhouse gases will be more obvious, which will further increase the pressure of CO2 emission reduction. Therefore, air quality and climate change cannot be solved in isolation, they are closely related.
Heavily polluted air conditions
It is necessary to develop more complex earth system models and long-term monitoring systems for climate and biogeochemical variables. Using this complex model of the earth system
Heavily polluted air conditions
It is a great challenge to simulate and predict the important physical, chemical and biological processes and feedback mechanisms in the above two aspects more accurately. If we try to maintain global warming in an environmental strategy with a specific threshold, we should not only consider reducing carbon dioxide emissions, but also consider measures to improve air quality and its climate consequences. In order to achieve maximum economic savings and win-win results, we should adopt emission reduction and low-carbon strategies to deal with air pollution and climate change, that is, we should adopt unified rather than separate scientific research and response strategies. Especially in the future, with the continuous control and improvement of air pollution, the cooling effect of aerosol can be greatly reduced, which will further increase the emission reduction of greenhouse gases in the future, otherwise the global temperature will rise at a faster speed and range. This strategy is particularly important for China, a developing country with rapid economic development, because these two problems not only exist at the same time, but also contribute to serious air pollution and rapid increase of greenhouse gas emissions due to the rapid growth of economic growth and energy consumption. Solving these two problems from the same source is not only more effective economically, but also can solve the problems of atmospheric environment and climate change at the same time.
In the adjustment of energy structure and industrial structure, the comprehensive or integrated technology of greenhouse gas and aerosol emissions should be considered at the same time, so that both emissions can be reduced and controlled; Organize all forces to compile the first relatively complete aerosol emission inventory in China; Further improve the observation network of greenhouse gases and aerosols, especially the aerosol observation network needs to be expanded and encrypted; Study the aerosol-cloud-climate change interaction between air pollution and climate change, and develop an ensemble model system in which climate models (global and regional models) and air pollution models are coupled and nested, so as to provide scientific basis and support for the establishment of medium and long-term air pollution and its environmental climate impact in China; Establish a coupling risk assessment system of air pollution and climate change, and provide an assessment of the consequences and severity of the impact on social and economic sectors according to their interaction and future scenario prediction. [3]
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Monitoring comparison
2011/February 5, foggy weather occurred in northern China, and the visibility was less than one kilometer, which led to the closure of highways between several provinces, exceeding
Citizens traveling in foggy weather
300 flights to Beijing were delayed or cancelled.
Citizens who travel in foggy days, the US Embassy in China issues PM2.5 monitoring every hour.
Data, the data shows that on February 4, 20 19 165438, the US Embassy in China monitored that the concentration of PM2.5 in Beijing was 522, the air quality index (AQI) was 500, and the health warning was "exceeding the standard index". Because in the AQI published by the US Embassy,
At the same time, the official Weibo "Green Beijing" of Beijing Environmental Protection Bureau releases the 1 monitoring data for the past 24 hours every afternoon, and then releases the forecast data for the next 24 hours. The air pollution index from noon 12 on the 4th to yesterday afternoon 12 was 193, and the quality grade was "light pollution level II".
The difference between the two grades caused controversy. The Beijing authorities explained that this is because the air quality standards of the two countries are different, but all Beijing residents feel that the air is far more than "light pollution". Some netizens ridiculed "Is the squad leader wearing a mask?" Drinking northwest wind may cause poisoning in the future. " [4]
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Monitor the implementation
take advice
201165438+February 5, the deadline for public comments on the Environmental Air Quality Standard (the second draft for comments). The opinion draft proposes to increase the average daily concentration limit of PM2.5 and the 8-hour ozone concentration limit in the basic monitoring project, and the new standard is planned to be fully implemented in 20 16.
In the standard exposure draft, the annual and 24-hour average concentration limits of PM2.5 are set at 0.035 mg/m3 and 0.075 mg/m3, respectively, which are the same as the target values of the World Health Organization (WHO) in the transition period 1 stage. According to the person in charge of the Science and Technology Standards Department of the Ministry of Environmental Protection, there are three major breakthroughs in the ambient air quality standard (draft for comment): First, adjust the division plan of ambient air quality functional zones and merge the three types of zones in the current standard into the second type; The second is to improve pollutant projects and monitoring standards, including increasing the average annual and daily concentration limit of PM2.5 and the 8-hour concentration limit of ozone in basic monitoring projects, and tightening the concentration limit of PM 10 and NO2. The third is to improve the validity requirements of data statistics. This is the first time that China has formulated national environmental quality standards for PM2.5.
Experts say that PM2.5 is a pollutant that seriously harms human health and has been scientifically confirmed. In recent years, the problem of PM2.5 pollution in China has become increasingly prominent. Incorporating PM2.5 into the scope of mandatory pollutant monitoring is conducive to eliminating or alleviating the phenomenon that the public's self-perception is not completely consistent with the monitoring and evaluation results. The annual and 24-hour average concentration limits of PM2.5 are set at 0.035 mg/m3 and 0.075 mg/m3, respectively, which are the same as the WHO target value in the transition period 1 stage, and meet the needs of China's current economic development stage and environmental management.
In addition, Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta and nine major urban agglomerations may be forced to monitor and publish the data of PM2.5 first, and the Twelfth Five-Year Plan for air pollution prevention and control may be approved by the State Council early next year. At the same time, Wu Dui, a researcher at Guangzhou Tropical Marine Meteorology Institute of China Meteorological Bureau, pointed out that the resistance to the release of PM2.5 came from local areas, and the manufacturing pressure in local areas prevented the release of PM2.5, which is a direct manifestation of the current concept of performance appraisal and the dominance of GDP.
The nine major urban agglomerations are the central Liaoning urban agglomeration, Shandong Peninsula, Wuhan and its surrounding areas, Changsha-Zhuzhou-Xiangtan, Chengdu-Chongqing, the west side of the Straits, Guanzhong, Shaanxi, north-central Shanxi and Urumqi urban agglomerations. [4]
Implementation time
201165438+February 2 1 day, at the seventh national environmental protection work conference, Minister Zhou Shengxian of the Ministry of Environmental Protection announced the schedule of PM2.5 and ozone monitoring, and the nationwide PM2.5 monitoring will be divided into "four steps". He said that in 20 12, PM2.5 and ozone monitoring will be carried out in key areas such as Beijing-Tianjin-Hebei, Yangtze River Delta and Pearl River Delta, as well as municipalities and provincial capitals; Monitoring in 1 13 key environmental protection cities and environmental protection model cities 20 13; 20 15 will be monitored in all cities above the prefecture level, and 20 16 is the deadline for the implementation of the new standards in China. By then, all parts of the country will monitor and evaluate the ambient air quality according to this standard, and release the monitoring results to the society.