Those who can meet the specific needs of users are beneficial to the health of users. There are no hidden dangers to human poisoning and injury. There are strict dimensional standards in the production process. Furniture designed according to ergonomic principles should have the following characteristics:  　　 1) Furniture materials tend to be natural and do not contain harmful substances.  　　 2) The green product is designed according to ergonomics and people-oriented. It not only pays attention to the physiological condition of the human body under static conditions, but also studies the physiological condition of the human body under dynamic conditions. It will not adversely affect and harm people in normal use and occasional misuse.  　　 3) Design the production to extend the product life cycle as much as possible to make it more durable and reduce energy consumption in reprocessing.  　　 4) The designed product has high grade and should have cultural heritage and scientific and technological content.  These furniture must be beneficial to the health of the human body. For the height of tables and chairs, the state has established standards. Among them, table furniture height standard is 700  The correct height of the table and chair should enable the person to maintain two basic verticals when sitting: First, when the two feet are placed on the ground, the thigh and the calf can be substantially perpendicular, and the front edge of the seat cannot form a pressure on the lower plane of the thigh. Second, when the arms are naturally drooping, the upper arm and the lower arm are substantially perpendicular, and the height of the table top should be just in contact with the lower plane of the lower arm, so that the person can maintain the correct sitting posture and writing posture. If the height of the table and chair is unreasonable, it will directly affect the sitting posture of the person, which is not conducive to the health of the user. For this reason, the space under the countertop of the writing desk is not less than  As for the size of the sofa, the front width of the single sofa seat should not be less than  There are also standards for bookcases, and the height of the shelf should not be less than  Manual Projector Screen,Cinema Screen,Movie Projector Screen,Pull-Down Projector Screen Dongguan Aoxing Audio Visual Equipment CO.,Ltd , https://www.aoxing-projectorscreen.com
What kind of furniture is safe?