The harm of free formaldehyde to the human body
Formaldehyde is a colorless, highly irritating gas that has been identified as a carcinogen and teratogen by the World Health Organization. Formaldehyde release pollution can cause respiratory diseases such as eye tearing, corneal and conjunctival congestion and inflammation, skin allergies, nasopharyngeal discomfort, cough, acute and chronic bronchitis, and can also cause nausea, vomiting, and gastrointestinal disorders. In severe cases, it can cause persistent headaches, pneumonia, pulmonary edema, loss of appetite, and even death. Long-term exposure to low-dose formaldehyde can cause chronic respiratory diseases, eye diseases, irregular menstrual disorders in women, pregnancy syndrome, neonatal malformations, and mental depression. In addition, it can also promote a decline in the physical fitness of newborns and cause heart disease in children. According to a survey by the US medical department, formaldehyde release pollution is the main reason for the increase in asthma among children aged 3 to 5 years old.
The harm of benzene to the human body
Benzene is a colorless, transparent, aromatic, volatile toxic liquid. It is a product of coal tar distillation or petroleum cracking and can evaporate at room temperature. , forms benzene vapor. The higher the temperature, the greater the volatilization amount. During occupational activities, benzene mainly enters the human body in the form of vapor through the respiratory tract. Inhaling high-concentration benzene vapor for a short period of time and inhaling low-concentration benzene vapor for a long time can cause physical damage to workers. Inhaling a large amount in a short period of time can cause acute mild poisoning, manifested by headache, dizziness, cough, chest tightness, excitement, and staggering gait. If inhalation continues at this time, severe acute poisoning may develop. The patient will be confused, have decreased blood pressure, muscle tremors, shallow and fast breathing, and a fast and weak pulse. Timely rescue can restore health within a few hours or days, but severe cases may also die due to paralysis of the respiratory center. Long-term low-concentration exposure can cause chronic poisoning, with symptoms gradually appearing, mainly in the blood system and neurasthenia syndrome, manifested as a decrease in white blood cells, platelets and red blood cells, dizziness, headache, memory loss, insomnia, etc. In severe cases, aplastic anemia, even leukemia, and death may occur.
The harm of radon to the human body
Radon is the only natural colorless, tasteless and odorless natural inert gas produced by the decay of radium. Radon is a radioactive gas that is ubiquitous in our living environment. Since the hazards of indoor radon were first discovered in the late 1960s, scientific research has found that the radiation damage caused by radon to the human body accounts for all environmental radiation to which the human body is exposed. More than 55% of the cases pose a great threat to human health, and most of the incubation periods are more than 15 years. Radon has been listed as an important indoor carcinogen by the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency has also listed radon as the most dangerous carcinogen. Therefore, we must pay high attention to the hazards of indoor radon.
Sources of radon: The foundation of the building and the surrounding soil account for about 60.4% of indoor radon, and the sources from building materials and outdoor air account for 19.5% and 17.8% respectively.
(1) Radon precipitated from foundation soil. High concentrations of radon can be found deep in soil and rocks containing uranium, radium, and thorium. Radon can enter the soil and atmosphere through fractures in the ground, and spread into the room along cracks in the ground. Generally speaking, low-rise housing has higher indoor radon levels.
(2) Radon precipitated from building materials (including interior decoration materials) is one of the main sources of indoor radon. Building materials usually contain varying degrees of radium, especially those made from industrial waste residues or by-products containing more radium. Part of the radon produced by the decay of radium enters the room through diffusion. In addition to its radium content, the radon elution capacity of building materials is also related to the porosity of the building materials, the size of the particles, the geometry of the pores, the water content in them, and changes in pressure.
(3) Radon brought into the room by outdoor air. The radiation dose of radon in the outdoor air is very low, but once it enters the room, it will accumulate in large amounts indoors. Indoor radon also has obvious seasonal changes: through experiments, it is highest in winter and lowest in summer. It can be seen that indoor ventilation conditions directly determine the harmfulness of indoor radon gas to the human body.
(4) Radon released during the combustion of water and natural gas. Radon is only harmful if the content of radon in water and natural gas is relatively high. The harm of radon and its progeny: The harm of radon to humans was first discovered in Germany more than 100 years ago. At that time, the incidence of lung cancer among miners in the Snyberg mining area in Germany was extremely high, so it was named "Snyberg disease". It was discovered 45 years later that this may have been caused by the mine having high radon concentrations in the air. It was not until the 1950s that radon was finally identified as one of the important causes of lung cancer.
In this way, people gradually understood the health hazards of radon and its short-lived daughters from the experience of increased incidence of lung cancer in miners who were long-term exposed to high levels of radon and its progeny.
The harm of radon to humans is mainly manifested in deterministic and stochastic effects. The deterministic effect is manifested in changes in blood cells in the body under exposure to high concentrations of radon. Because radon has a high affinity for human fat, especially when radon combines with the nervous system, it is more harmful. The random effect is mainly manifested as inducing tumors. Because radon is a radioactive gas, radon gas and its progeny enter the lungs with the airflow when breathing. When the radon progeny decays, it emits rays. These rays bombard lung cells like small bombs, damaging lung cells and leading to the possibility of lung cancer. sex. If the particles released during radon decay enter the human body through breathing, they will damage the DNA of cell tissues and induce cancer. The American Surgical Association estimates that the resulting lung cancer accounts for about 15% of lung cancer incidence, second only to smoking. At the same time, radon has a high solubility in liquids and fats. It will accumulate in fat-rich organs and decay to produce radon progeny, causing harm to the human body. Under the influence of high concentrations of radon, the human body shows effects such as an increase in the total number of blood cells (red and white blood cells), a decrease in blood pressure, and dilation of blood vessels. The alpha rays emitted by radon progeny are one of the main causes of lung cancer and blood diseases in the human body. External radiation from α and β rays can damage the human body’s facial features, causing dry skin, hair loss and other pathological changes. In severe cases, it can cause skin cancer. Medical research has confirmed that radon may also cause leukemia, infertility, fetal malformation and other consequences.
Each organ of the human body is exposed to different degrees of radiation dose from radon progeny, among which the lungs receive the largest dose. The dose distribution produced by radon progeny in the lungs is also uneven. The dose in the tracheobronchial epithelial basal cell layer is much higher than the average dose in the lung area or the whole lung. Because lung mass and breathing rate change with age, for a given concentration of radon progeny in the air, the effective dose equivalent may reach a maximum at about 6 years old, which is about 2.5 times higher than the effective dose equivalent at 30 years old. On average, the effective dose equivalent produced by a unit of exposure for children under 10 years old is about 1.5 to 2 times that of adults. Therefore, the main harm caused by radon and its progeny to long-term exposed persons is the increased incidence of lung cancer, especially for children.
Scientists have calculated that living in an environment with an indoor radon concentration of 200 Bq/m3 is equivalent to smoking 15 cigarettes per person per day. Scientific research shows that radon is the second largest cause of lung cancer after smoking. The World Health Organization lists it as one of 19 major environmental carcinogens. The International Agency for Research on Cancer also considers radon to be an important indoor carcinogen.
Radon concentration control measures
(1) Frequent ventilation to keep the pressure difference between indoor and outdoor at zero
(2) Laying down an isolation layer, which can Reduces the amount of radon entering newly constructed homes to some extent.
(3) Anti-radon coating
Covering decorative veneers on the wall surface can reduce the precipitation of radon, and applying certain coatings on the walls and floors can effectively inhibit the precipitation of radon. If there is white ash on the outside of the brick, the precipitation rate can be reduced by about three times. If the white ash is coated with paint, the precipitation rate will be reduced by one time. If a layer of material with better sealing properties is applied to the inner surface of the underground project, it can prevent some radon from leaching out, thus reducing the radon leaching rate. Generally, materials with better moisture-proof properties also have better radon-proof properties. This is because moisture-proof materials generally have good sealing properties. They prevent moisture from dispersing and also prevent radon from escaping. There is a radon-proof and moisture-proof paint called "RadonSeal" abroad. When this paint is applied to concrete or bricks, it can penetrate to a certain depth, increase the compactness and strength of concrete and bricks, and achieve better results. Anti-radon effect. A domestic college has researched an environmentally friendly anti-radon interior wall paint that uses cross-polymerization of double-layer film materials to form a film, which improves the density and durability of the paint and prevents radon and moisture.
The harm of ammonia to the human body
Chemical properties of ammonia: Ammonia is a colorless gas with a strong pungent odor, lighter than air (specific gravity is 0.5). The harm of ammonia to the human body: Ammonia is an alkaline substance that has corrosive and irritating effects on the skin tissue it comes in contact with. It can absorb moisture in the skin tissue, denature tissue proteins, saponify tissue fat, and destroy cell membranes. structure. When the concentration is too high, in addition to the corrosive effect, it can also cause cardiac arrest and respiratory arrest through the reverse effect of the trigeminal nerve endings.
Ammonia is usually inhaled into the human body in the form of gas and enters the alveoli. After being inhaled into the lungs, ammonia easily enters the blood through the alveoli, combines with hemoglobin, and destroys the oxygen transport function. Ammonia has extremely high solubility, so it mainly has irritating and corrosive effects on the upper respiratory tract of animals or humans, weakening the body's resistance to disease. A small amount of ammonia is neutralized by carbon dioxide, and the remaining small amount of ammonia is absorbed into the blood and excreted from the body with sweat, urine or respiratory tract. Some people who are exposed to ammonia for a long time may develop symptoms such as skin pigmentation or finger ulcers; short-term inhalation of large amounts of ammonia may cause tears, sore throat, hoarseness, cough, blood-streaked phlegm, chest tightness, difficulty breathing, and may be accompanied by dizziness and headache. , nausea, vomiting, fatigue and other symptoms. In severe cases, pulmonary edema, adult respiratory distress syndrome, and respiratory tract irritation symptoms may occur. Therefore, alkaline substances cause deeper and more serious damage to tissues than acidic substances. In order to prove that low concentrations of ammonia in the air are harmful to human health, experts monitored workers working in an indoor environment with ammonia concentrations of 3 to 13 mg/m3 for 8 hours, with 10 people in each group. Comparing them with healthy people who were not exposed to ammonia, it was found that the levels of urea and ammonia in the urine of the experimental group increased, and the urea in the blood increased significantly.
The sources of ammonia in the air: (1) Mainly from concrete admixtures used in construction. Especially during winter construction, concrete antifreeze containing urea and ammonia as the main raw materials is added to the concrete wall. . These admixtures containing a large amount of ammonia substances are reduced to ammonia gas in the wall as environmental factors such as temperature and humidity change, and are slowly released from the wall, causing a large increase in the concentration of ammonia in the indoor air. (2) Additives and brighteners in interior decoration materials Ammonia in indoor air can also come from additives and whiteners in decoration materials. However, this kind of pollution has a relatively fast release period and will not accumulate in large amounts in the air for a long time, so it is less harmful to the human body.
The harm of TVOC to the human body
Total volatile organic compounds (TVOC): Volatile organic compounds are commonly represented by VOC, the abbreviation of the first letter of the three words Volatile Organic Compound, but sometimes Also expressed as total volatile organic compounds TVOC. TVOC is one of the three organic pollutants (polycyclic aromatic hydrocarbons, volatile organic compounds and aldehydes) in the air that has the most serious impact. VOC refers to organic matter whose saturated vapor pressure exceeds 133.32pa at room temperature. Its boiling point is between 50°C and 250°C. It can exist in the air in the form of evaporation at room temperature. Its toxicity, irritation, carcinogenicity and special odor Sex, will affect the skin and mucous membranes, causing acute damage to the human body. The World Health Organization (WHO), the National Academy of Sciences/National Research Council (NAS/NRC) and other institutions have always emphasized that TVOC is an important type of air pollutant. TVOC can smell and be irritating, and some compounds are genotoxic. TVOC can cause imbalance in the body's immune level, affect the function of the central nervous system, and cause subjective symptoms such as dizziness, headache, drowsiness, weakness, and chest tightness; it may also affect the digestive system. , loss of appetite, nausea, etc. may occur. In severe cases, the liver and hematopoietic system may be damaged, and allergic reactions may occur.
TVOC is divided into eight categories: alkanes, aromatic hydrocarbons, alkenes, halogenated hydrocarbons, esters, aldehydes, ketones and others. They all occur in micro and trace levels, so they can easily go unnoticed. They mainly come from: organic solutions: such as paints, aqueous coatings, adhesives, cosmetics, detergents, caulking glue; building materials: such as artificial panels, foam insulation materials, plastic sheets; interior decoration materials: such as wallpaper, others Decorations, etc.; fiber materials: such as carpets, tapestries and chemical fiber curtains; incomplete combustion of household fuel and tobacco leaves, human excrement.