In the natural environment, the normal level of carbon dioxide in the air is 0.04% (400 PPM), when the concentration of carbon dioxide reaches 1% (1000 PPM), people will feel dull, inattentive, palpitations, etc.; when the concentration of carbon dioxide reaches 1500-2000 PPM, people will feel shortness of breath, headache, dizziness; and when the concentration of carbon dioxide reaches 5000 When the concentration of carbon dioxide reaches 5,000 PPM or more, the body’s functions are seriously disrupted, with loss of consciousness and confusion.