It is a well known fact that smoking is hazardous to health. Not only do smokers’ health suffer, but passive smokers also suffer from malignancies, asthma, bronchitis, pneumonia, and other diseases caused by inhaling secondhand smoke, the mainstream smoke exhaled by smokers, as well as sidestream smoke that comes directly from burning tobacco. However, the dangers of smoking go far beyond this. Blowing away the “third-hand smoke” can also be harmful to the health of people, especially infants and children. What is third-hand smoke? The harmful substances in the smoke produced by burning cigarettes are difficult to dissipate in a short time, even after the cigarette is extinguished. “Wherever you smoke, the harmful particles in the smoke will be adsorbed to your hair, skin, clothes, carpets, sofas and car seat covers. These toxic ingredients include hydrocyanic acid, butane, toluene, arsenic, lead, carbon monoxide, polonium 201 and more than 10 other highly carcinogenic compounds. When you smoke and then come into contact with your child, your child will still be exposed to the harmful substances produced by burning cigarettes in the environment.” We refer to this phenomenon as “third-hand smoke. Because infants and children can inhale contaminants close to themselves or touch and lick contaminated surfaces, they are highly exposed to the hazards of “thirdhand smoke. In addition, “third-hand smoke” stays indoors for quite a long time, and they remain after the cigarette is extinguished. Researchers say that because of the small body surface area of infants and young children, low levels of smoke particles can cause cognitive deficits in children, similar to low levels of lead in the environment. Studies have shown that the longer children are exposed to smoke particles, the worse their reading skills become. Even at very low levels, there is still a risk of neurotoxicity in infants and toddlers. Crawling babies and toddlers use their senses of touch and taste to explore the world. Their wet hands like to stuff whatever they grab into their mouths, and they often crawl and play on carpets and sofa beds. If an infant’s parents have a bad habit of smoking, the curious infant is likely to become a victim of “third-hand smoke. Up to 90 percent of the nicotine in smoke clings to the surfaces of nearby objects, and babies may inhale nicotine and other harmful compounds when they hug their mothers, even if their mothers never smoke around their babies, said George Matter, a professor at San Diego State University. In a small study of 49 infants under 13 months of age, nicotine was found to be present in the air and dust of smokers’ houses, even when they did not smoke indoors. Tests also found cotinine, a metabolite of nicotine, in the infants’ urine and hair. According to the study, as expected, infants whose parents smoked near them had the highest levels of cotinine, nearly 50 times higher than those whose parents did not smoke. Matt said smoker parents who try to protect their infants only receive partial results. The study showed that the babies of smokers who did not smoke in the home had seven times higher levels of cotinine than those of non-smokers. Matt’s research shows that adults are also at risk of becoming harmed by smoke residue if they rent a car, hotel, or apartment that suffers from cigarette exposure year-round. Young people may be exposed to smoke residue throughout the day. Jonathan W. W. Wickoff, an assistant professor of pediatrics at Harvard Medical School, said that because of the high risk of smoke exposure, young people can be exposed to smoke residue throughout the day. Weidinkopf said that because small children breathe faster than adults, they will inhale more chemicals. And infants who can only crawl may be exposed to chemicals through their skin. As a result, they may be at greater risk because children’s weight is relatively low compared to adults, the same level of toxic substances cause more harm to children. And because of their activity characteristics, they are more likely to come into close contact with harmful substances left in the environment. In addition, children are in a special period of growth and development, their resistance to harmful substances is much lower than that of adults. Therefore, tobacco residues in the environment, including lead and arsenic and other toxic substances, can cause considerable harm to children’s nervous system, respiratory system, circulatory system, etc. Many parents currently believe that smoking while their children are outside and then opening windows to ventilate the room will not be harmful to their children’s health. Such a misconception needs to be corrected. These findings coincidentally confirm the concept put forward by the WHO – there is no safe bottom line for tobacco exposure! Recent surveys have found a lack of awareness of the dangers of third-hand smoke. A telephone survey of 2,000 households counted people’s responses to the question, “Does smoking yesterday have an adverse effect on indoor air today, and is it harmful to children? Of the 1478 respondents who answered all questions, 273 were smokers. The overall results showed that more than 95.4% of non-smokers and 84.1% of smokers were aware of the health risks of secondhand smoke to children. In contrast, 65.2% of nonsmokers and 43.3% of smokers recognized the harm of thirdhand smoke to children. Awareness of the risks of thirdhand smoke was significantly associated with whether smoking was banned in the home. After recognizing the health risks of “secondhand smoke” to others, many smokers have changed their smoking habits. However, researchers have recently published findings that show that even when smokers smoke away from passive smokers, the harmful emissions from smoking can still affect the health of others. Therefore, it may be in the best interest of smokers to give up the cigarette in their hands. For this reason, we call for a ban on smoking in rooms where children live. The health risks of “third-hand smoke” are real, and increased awareness of how “third-hand smoke” can harm children’s health can facilitate the development and implementation of family smoking bans, as well as the integration of “third-hand smoke “pollution into tobacco control and health management.