Secondhand smoke contains a lot of harmful substances that can cause a lot of harm to babies, such as respiratory diseases, ear infections, tooth decay, and sudden infant death syndrome. 1. Respiratory diseases: respiratory diseases and the degree of smoking is almost directly proportional to, for example, will trigger bronchitis, bronchitis, asthma in children, etc., second-hand smoke can increase the number of asthma attacks and aggravate the severity of asthma. 2. Ear inflammation: Harmful substances in second-hand smoke directly stimulate the mucous membrane of the middle ear, so that the secretion and mucus in the middle ear increases and thickens, and also makes the Eustachian tube not smooth, thus causing otitis media and middle ear effusion. 3. Tooth decay: second-hand smoke will have a negative impact on the baby’s oral flora, the mineralization process of the development of milk teeth, but also affects the development of salivary glands, increasing the risk of tooth decay in children. 4. Sudden Infant Death Syndrome (SIDS): Inhalation of secondhand smoke is one of the known causes of SIDS, while increasing the risk of morbidity. Secondhand smoke is very harmful to babies, in order to their own health and children’s health, it is recommended to quit smoking in a timely manner, pay attention to let the baby away from the secondhand smoke environment.