Many of us are used to put mothballs into the closet to prevent insects, moths and mildew. Mothballs are what we call sanitary pills and stinky beads, which will give off an odor, and mothballs rely on these odors to repel insects and prevent mildew. But we not only ask, is the odor emitted by mothballs harmful to human body? To know whether the smell from mothballs is harmful to human body, first of all, it is necessary to analyze the type and composition of mothballs. Mothballs are divided into natural mothballs and synthetic mothballs. Natural mothballs are smooth colorless or white crystals that float in water, which are organic compounds with aromatic smell extracted from camphor tree branches and leaves and are non-toxic. It can be used not only for insect prevention, moth prevention and mold prevention, but also for pharmaceuticals, spices, etc. It can also be used as cardiac drug in medicine. Synthetic mothballs are a kind of synthetic organic compounds, the active ingredient is mainly naphthalene or p-dichlorobenzene, mostly white, with pungent smell and sinking in water. From this, we can easily know that the odor emitted by natural camphor pills is not harmful to human body and can be used safely, but one point should be clear that natural camphor resources are limited, and it is difficult to buy natural camphor pills in the market. Most of the mothballs in the market are synthetic mothballs, and synthetic mothballs are mainly harmful to human body, such as naphthalene or p-dichlorobenzene, which are toxic and volatile organic compounds. Prolonged human exposure will cause dizziness, vomiting, skin allergy, numbness of limbs and other symptoms. Excessive use can also cause lung dysfunction, liver damage, acute hemolytic anemia, and irritation of the whistle. In serious cases, it can even cause cancer. Therefore, when we use mothballs, we must pay attention to distinguish them clearly, if they are not natural mothballs, it is not recommended to use them.