Is the dust formed by chalk for lectures harmful to human body?

Chalk teaching aid is an indispensable tool in current teaching. Imparting knowledge is one of the most primitive and traditional teaching methods. Chalk has been used for thousands of years and made an indelible contribution to human education. With the progress of history and the development of society, people's understanding of chalk teaching AIDS is constantly improving. That is, chalk not only brings great progress and contribution to human education, but also brings great harm to teachers and students engaged in education.

According to the survey data of the whole country and our province, with the progress of society and the acceleration of social rhythm, the occupational disease rate of teachers is increasing year by year, and the occupational diseases are developing in a diversified direction. Among them, pneumoconiosis caused by dust and various acute and chronic respiratory diseases are the most important, harmful and extensive occupational diseases in China. The prevalence of myopia among students is also increasing year by year, reaching an extremely serious level. For example, Tian Beichen, an education expert, visited Fuzhou on 1995. A questionnaire survey of 3 125 primary and secondary school teachers in 30 middle schools and 6 primary schools shows that the prevalence of chronic respiratory diseases among primary and secondary school teachers is high. Common diseases are chronic pharyngitis and vocal cord diseases. Among them, the prevalence rate of chronic diseases in men is 58.53%, and that in women is 665,438+0.06%, and both of them tend to increase with the increase of teaching experience. Education expert Niu et al. 1996. In February, 240 primary school teachers in Kaifeng were investigated. The results show that teachers have different degrees of throat diseases, and the incidence rate is 60.4%. In 1999, the education expert Lu equals 65,438+0,999. A survey of diseases among 62 college teachers in Qingdao 1 showed that 89 cases were chronic laryngitis, accounting for 54.94%, and 69 cases were chronic laryngitis, accounting for 42.59%. A survey of 2 19 teachers in the second primary school in Jinshui District shows that the prevalence rate of teachers' pharyngitis is 100%, rhinitis is 39%, asthma is 43%, bronchitis is 8%, pneumoconiosis is 1 1.76% and cancer is 2%.

In addition, the long-term survey data of students' myopia caused by black and white blackboard writing and classroom dust pollution show that compared with the similar data of 1992, there are 22 provinces (cities, autonomous regions) in China, and the average decline rate of students' eyesight increased by 23.45% during 10. At present, the low vision rate of primary school students in China is 265,438+0.965,438+0%, the low vision rate of junior high school students is 55.86%, the low vision rate of senior high school students is 75.79%, and the low vision rate of college students is close to 80%, showing an upward trend every year. According to a survey of 2839 students in 57 middle schools in Jinshui District of Zhengzhou City, it is shown that

Because dust contains carcinogens, the data of China Center for Disease Control and Prevention show that the cancer incidence rate of 38 million full-time teachers in China accounts for 20% of the total cancer incidence rate in China, which is more than 8 times that of the general population.

After studying the distribution and harm of classroom dust with system dynamics model, it is found that the working environment is very similar to the severity of dust harm to workers in front of steelmaking furnace in the diameter space of 3m of the podium.

As far as its chemical composition is concerned, chalk is mainly composed of calcium carbonate (limestone) and calcium sulfate (gypsum), with a small amount of calcium oxide and other metal elements, such as iron and cadmium. Even if the original chalk on the market is improved into dust-free chalk, only grease or polyol is added as binder, and then raw materials with higher specific gravity are added, so that the specific gravity and volume of chalk are increased and it is not easy to fly away, but it is not obvious in practical application. According to the chemical pH value of chalk, it belongs to weak alkaline substance. From its physical properties, it is chalk in the process of writing and erasing chalk. According to the main chemical composition, concentration, dispersion, specific gravity, shape, hardness and solubility, a large amount of dust is produced in the whole teaching process, which floats in the air for a long time, seriously polluting indoor air, endangering the physical and mental health of teachers and students, endangering modern teaching auxiliary equipment with modern characteristics such as slide projectors, projectors, computers and laboratories, and affecting the performance, service quality and service life of these equipment. At the same time, due to extensive use, it is inevitable to mine a large number of limestone, minerals and minerals.

Among them, the harm of dust to the physical and mental health of teachers and students is mainly reflected in the following aspects:

Harm to the respiratory system of teachers and students

1. Harm to the lungs: Dust is harmful to the health of teachers, especially the lungs. In the teaching process, chalk dust is easily inhaled into the lungs, and most of it is blocked in the alveoli. After a series of stimulation, chemical and immune actions, it can lead to the loss of lung function, including respiratory inflammation and decreased lung ventilation function. Common lung diseases are: chronic and acute pneumonia, lung cancer, pneumoconiosis and so on.

2. Harm to the upper respiratory tract: chalk dust enters the lungs through the upper respiratory tract, including the nose, pharynx and bronchus. In this process, some dust will stay in the upper respiratory tract, causing mechanical stimulation and damage to mucosal epithelial cells. Working in this environment for a long time will cause a series of pathological changes. Among them, the most common effect on the nose is to induce dry rhinitis, followed by hypertrophic rhinitis. Symptoms are dry nose, stuffy nose and congestion of nasal mucosa. The main effects on pharynx are chronic pharyngitis, dry throat, uncomfortable expectoration, sore throat and itchy throat, and the main effects on bronchus are chronic bronchitis and sometimes asthma. In addition, it may cause nasopharyngeal carcinoma and bronchial cancer.

Damage to other organs and tissues

1. Injury to eyes: The eyes are one of the most delicate and easily damaged organs of the human body. The main components of chalk ash, such as calcium carbonate and calcium oxide, are water-soluble substances, which are easily soluble in water and produce alkaline substances. For example, when a teacher falls into the eyes during the teaching process, it stimulates the secretion of lacrimal glands, and tears hydrolyze calcium carbonate to produce alkaline substances, which will seriously stimulate the eye mucosa, cause mucosal damage and form chronic inflammation.

2. Damage to the skin: In the teaching process, chalk dust will inevitably stick to the hands. At the same time, particulate dust floating in the air will also fall on the teacher's hair, face and neck, which will stimulate the skin membrane. If you sweat in summer, it will produce alkaline substances, which will stimulate the skin and mucosa more. Because the environment of human skin is weakly acidic, it will destroy the basic living environment of skin under the action of dust alkalinity. Chalk dust can change the skin. It's dry and rough, accompanied by itchy feeling, which makes people very uncomfortable. In severe cases, it can cause acne, folliculitis, pyoderma, chapped skin and a lot of hair loss, which affects and interferes with teachers' normal work and life.

3. Harm to ears: chalk dust enters the external auditory canal. Mixed with sebum, cerumen embolism can be formed. If this continues for a long time, it will cause ear inflammation.

3. Induce other diseases.

At present, the composition of chalk in the market contains low metal elements, such as lead, manganese and barium, but high cadmium. After cadmium is inhaled by human body, it is mainly stored in liver, kidney and bone tissue, which has obvious damage effect. The main pathological changes caused by long-term exposure to cadmium compounds are emphysema and renal damage. The disease will develop gradually. Initial symptoms include weakness, emaciation, dizziness, insomnia and dreaminess, anorexia, neurasthenia, etc. Atrophy and ulcers. Emphysema progresses slowly. The patient developed progressive dyspnea, increased activity and palpitation. Cadmium is also one of the most likely carcinogenic metal elements.

Fourth, the impact on air quality.

Chalk ash has a strong adsorption capacity. Many harmful bacteria can be adsorbed on fine dust and brought into students' lungs, leading to acute and chronic inflammation, which leads to collective infection of infectious diseases such as respiratory tract of students. During the course of students' attending classes, the indoor and total bacterial count are getting worse, which will interact with fine chalk dust and aggravate the harm of chalk dust to the health of teachers and students.

Influence of Five Chalks on Students' Myopia

For a long time, our teaching tools are blackboard, metal green board and chalk. Students often use black and white words in books. Because people's vision recognizes fonts and their colors through light perception and color perception, the contrast between black and white is too strong, which is easy to cause visual fatigue, thus causing students' large-scale myopia. According to Lu Naichi, an ophthalmologist in Shanghai, he put forward a new concept of preventing myopia by improving the visual environment in his research, and pointed out that students' myopia is mainly caused by the visual environment rather than bad eye habits. He pointed out that when people read a book, their eyes feel the shape of the font by comparing the chromaticity and brightness between the font and the paper. Chroma is directly proportional to the purity of reflected light, and brightness is directly proportional to the intensity of reflected light. White light can only cause the weakest color vision and the maximum light intensity. When people get the maximum brightness contrast, they will also lead to the greatest visual fatigue, which will lead to functional accommodation myopia for a long time, thus finding beige. The softest color is the most conducive to protecting students' eyesight. According to Dahe Daily, in 2002, Shanghai promoted beige textbook education in the whole city. In addition, Guangdong, Hunan and other provinces have also begun to promote the use of beige textbooks. Shanxi University and other units have developed beige dust-free teaching boards and put them on the market, with good response. More than a dozen schools in our city have used it.

Teachers are engineers of the human soul. They are also noble occupations. Students are the future of the motherland. Their physical and mental health has attracted the attention of the government and society. The concept of green environmental protection has been deeply rooted in people's hearts. Behind the huge education industry, how to completely eliminate the chalk dust pollution in the classroom and protect the health of teachers and students has become a difficult problem that all levels of government and society in China pay close attention to and begin to solve. The population of our city is 6.877 million (end of 2002). The total number of students in school is more than 2124,000, including full-time teachers100,000. The health level of a large group of teachers and students and the improvement of working and learning environment directly restrict the implementation of the strategy of running a well-off society in our city, directly affect the sustainable development of China's education, and also affect and restrict the improvement and improvement of China's educational hard environment.

Suggestion: It needs the joint efforts of the party, the government and the whole society to completely solve the chalk dust pollution. In view of the actual situation of our city's economic development level, we put forward the following suggestions:

1. Set up a leading group to solve classroom dust pollution, formulate relevant restrictions and support policies, encourage and guide classroom dust-free transformation, limit the development of blackboard chalk, support the research and development of dust-free teaching AIDS, take classroom dust-free as a hard indicator for residents in our province to run towards a well-off society, and establish a green campus. Support the research and development, sales and production of dust-free research tools from taxation and other aspects, and guide the dust-free education industry in our province.

2. As the environmental protection investment in education, the government has allocated some special funds to support and encourage the production and circulation enterprises of dust-free teaching AIDS. At the same time, collect a certain amount of classroom dust pollution fees from circulation enterprises and users of green board and blackboard production enterprises to supplement the classroom dust-free renovation fund, which is specially used for classroom dust-free renovation.

3. Intensify propaganda, correctly guide classroom dust-free transformation, make the whole society pay attention to the harm of classroom chalk dust, and let more social forces invest in the research, development, production and sales of new dust-free teaching AIDS and classroom dust-free transformation.