A, about PM2.5 you do not know those things PM50, PM10, PM2.5, are 3 critical values, the air is not only these 3 diameters of particulate matter, below 50 microns, above any diameter length of particulate matter. 50 microns is the critical value visible to the naked eye, which can enter the nasal cavity, but cannot move on. The nasal hairs in our nasal cavity, which look dense, are sparse for PM50. The nasal hairs can block PM100 and PM75, but not PM50, and what can block PM50 are the cilia of the mucous membrane cells in the nasal cavity, which are invisible to the naked eye and very dense. Moreover, the mucus secreted by the mucous membrane cells in the nasal cavity can also stick PM50, so that they can’t move forward. When it accumulates to a certain level, we want to blow our nose and dig our nose, but don’t do it in public, it is indecent in public. 10 microns is the threshold value that can reach the throat, so the fine particles below PM10 are called “respirable particulate matter”. The throat is the terminus of PM10, the mucus secreted by the mucous membrane cells on the surface of the throat will stick to them, and each mucous membrane cell has 200 cilia (also invisible to the naked eye), which are constantly swinging upwards, just like paddling a dragon boat against the water. We are born with this physiological function to stop PM10 from continuing its downward journey. PM10 accumulates in the upper respiratory tract, where the throat is located, and the more it accumulates, the more mucus is secreted. When it accumulates to a certain level, we want to spit. Therefore, phlegm should be spit, not swallowed, swallowing is harmful. 2.5 microns is the threshold value that can reach the alveoli. fine particles below PM2.5, the upper respiratory tract can not be blocked, they can go down smoothly, into the fine bronchi, alveoli. Our respiratory system is like the root system of plants, from top to bottom, the trachea divides into bronchi, bronchi divides into dense fine bronchi, and dense fine bronchi are connected to dense alveoli, the number of alveoli are 300 to 400 million. The oxygen inhaled eventually enters the alveoli, and then enters the capillaries through the walls of the alveoli, and then enters the whole blood circulation system. The PM2.5 we breathe in, because it is so small, can also enter the alveoli, and then through the walls of the alveoli into the capillaries, and then into the entire blood circulation system. PM2.5 carries many harmful organic and inorganic molecules, which are the source of disease. Bacteria are known to be the source of disease, and PM2.5 has a comparison with bacteria. PM2.5 is a fine particulate matter with a diameter of 2.5 microns, while bacteria are micron-sized organisms, mostly 1 micron, several microns, and a dozen microns in size. In other words, PM2.5 and bacteria are of average size. When bacteria enter the blood, macrophages (a kind of immune cells) in the blood immediately come over and swallow it, and it cannot cause people to get sick, just like a tiger eating a chicken. When PM2.5 enters the blood, the macrophages in the blood think it is a bacteria and immediately come over and swallow it. Macrophages are used to swallowing bacteria, which are alive and are food for macrophages. However, PM2.5 is inanimate, and macrophages swallow it, just like a tiger swallowing a stone, and eventually choke to death, then our immunity will be reduced. Not only that, the choked macrophages, however, release a substance which can lead to inflammation of cells and tissues. As you can see, PM2.5 is more pathogenic than bacteria. The more PM2.5 that enters the bloodstream, the more likely we are to get sick. Second, the harm of PM2.5 to human body 1, cause respiratory obstruction or inflammation Research shows that 75% of the particles below 2.5 microns are deposited in the alveoli. We can imagine that the eyes will be inflamed when sand is in them. Deep in the respiratory system, which is also a sensitive environment, fine particulate matter stays as a foreign body in the respiratory system for a long time, and it will likewise inflame the respiratory system. 2.Pathogenic microorganisms, polycyclic aromatic hydrocarbons, oil smoke, etc. Ride the “hitchhiker” into the body to cause cancer. In addition to their own “bad things”, fine particles are also like a car that can freely enter the respiratory system, other disease-causing substances such as bacteria, viruses, hitchhiking “hitchhiker” to the depths of the respiratory system, causing infection. Do not think that as long as you stay away from the poor diet of large fish and meat, you can avoid cardiovascular disease, fine particles also have many “ways” to induce cardiovascular disease. For example, fine particles can enter the bloodstream directly and induce the formation of blood clots. Another indirect way is that fine particulate matter stimulates inflammation in the respiratory tract, and then the respiratory tract releases cytokines that cause vascular damage and eventually lead to the formation of blood clots. Epidemiological investigations have found that polycyclic aromatic hydrocarbons (PAHs) in urban atmospheric particulate matter are associated with the incidence and mortality of lung cancer in the population. Most of the PAHs in the atmosphere are adsorbed on the surface of the particles, especially those below 5 mm in size, and very few PAHs are found on large particles. In other words, the more fine particulate matter in the air, the more chances we have to be exposed to carcinogens – PAHs. 3.Impact on fetal development causing defects There are also some findings that make people more worried. Several reports in recent years have shown that human fertility is declining significantly, and environmental pollution is believed to be the culprit. An investigation from northern Bohemia, which studied pregnant women exposed to high levels of PM2.5, found that high levels of fine particulate pollution may affect embryonic development. Additional studies have found that concentrations of atmospheric particulate matter correlate with increased perinatal and neonatal mortality, low birth weight, intrauterine growth retardation (IURG), and congenital functional defects. 4, PM2.5 particulate matter can enter blood vessels through air-blood exchange An experiment in 2009 collected PM2.5 in the Beijing urban atmosphere to study the toxicological effects of a human alveolar epithelial cell line (A549) as a model. In this experiment, comparisons with different staining conditions of 25, 50, 100, and 200 μg/ml revealed that PM2.5 caused inflammatory damage in these cells as the staining concentration increased. Between 2004 and 2006, when the daily average PM2.5 concentration increased at the Peking University campus observation site, the number of emergency cardiovascular patients also increased at Peking University Hospital No. 3, about 4 km away. “Using a time-series analysis study, we analyzed the collected data and found that an increase of 10 micrograms per cubic meter of PM2.5 concentration was associated with an 8% increase in hospital emergency patients in the hypertension category and an increase in cardiovascular disease.” Third, the World Health Organization (WHO) that PM2.5 less than 10 is a safe value, and all of these areas in China are higher than 50 close to 80! Air Quality Index: Air Quality Index (AQI) is defined as a quantitative description of the air quality status of the dimensionless index, for individual pollutants also provides the air quality sub-index ( IndividualAir Quality Index (IAQI). The IAQI can be used to visually evaluate the quality of the air environment and guide the control and management of air pollution. Air quality is divided into five levels according to the size of the air quality index, corresponding to the six categories of air quality, the larger the index, the higher the level indicates that the more serious the pollution situation, the greater the health risk to humans. 0～50 Ⅰ excellent can be normal activities 51～100 Ⅱ good 101～150 Ⅲ1 light pollution susceptible people have mildly increased symptoms, healthy people appear irritating symptoms heart disease and respiratory disease patients should reduce physical exertion and outdoor activities 151～200 Ⅲ2 light pollution 201～250 Ⅳ1 moderate pollution heart disease and lung disease patients have significantly increased symptoms, exercise tolerance is reduced, healthy The elderly and patients with heart, liver and lung diseases should reduce physical activity 251 to 300 Ⅳ2 moderate heavy pollution 301 to 500 Ⅴ heavy pollution Healthy people with reduced exercise tolerance, there are obvious strong symptoms, the early appearance of certain diseases elderly and sick people should stay indoors to avoid physical exertion, the general population should minimize outdoor activities.