1, traditional chalk (dust-free chalk)
Chalk varies according to age, region, and manufacturer. The earliest use of chalk is lime and water, made of blocky to use. Now, the domestic use of chalk mainly have ordinary chalk and dust-free chalk two, its main components are calcium carbonate (limestone) and calcium sulfate (gypsum), or contain a small amount of calcium oxide.
2, liquid chalk (no dust liquid chalk, environmental protection liquid Chalk and other names)
Organic pigments, edible alcohol, environmental auxiliaries, etc.
The above can be seen, although the ordinary chalk composition is not poisonous, but when wiping a lot of dust, directly affect the health of teachers and students, writing extremely easy to break, easy to damage the blackboard. Pollution to the classroom environment, but also endanger the health of teachers and students!
Liquid Chalk dust-free, easy to rub, writing fluent, no noise, can reduce the fatigue on the blackboard! A point of absolute dust-free, it is conducive to the classroom air, so that teachers and students get rid of dust pollution!
We are looking at the hazards of dust: chalk ash induces teachers and students disease epidemic prevention station in Shanxi province Joseph Yam's test found that, in addition to containing lead, manganese, barium and other metal elements, the content of metal cadmium in chalk dust is higher. Cadmium is one of the most important pollutants in human body, cadmium is inhaled by the human body, mainly stored in the liver, kidney, bone tissue, the damage to these tissues is obvious, long-term exposure to cadmium-containing substances will cause emphysema and kidney damage and other diseases. The course of disease can be progressive development, early performance of weakness, weight loss, dizziness, inattention, daytime sleepiness, sleepless nights, more dreams, anorexia symptoms such as loss of appetite, and nasal bleeding, chronic nasopharyngeal inflammation, nasal mucosal atrophy and ulcers and other phenomena. The patient mainly shows waist back pain, joint pain, systemic pain and so on. Slow progression of emphysema, patients with progressive dyspnea, increased activity, accompanied by palpitation. Cadmium is also one of the most likely causes of cancer.