Passive secondhand smoke can be reduced by increasing exercise, eating more selenium-rich foods, eating more high-vitamin foods to minimize the damage caused by secondhand smoke, and the most effective way is to stay away from the secondhand smoke environment. 1. Increase the amount of exercise: more exercise can speed up the metabolism of lung tissue and reduce the possibility of many lung diseases. For people who regularly inhale secondhand smoke, it is important to increase the amount of exercise, such as yoga, jogging and all kinds of ball games. 2. Eat more selenium-rich foods: If you’re a frequent smoker, it’s best to start with your daily dietary regimen. As smoking can lead to lower selenium levels in the blood, and selenium has an anti-cancer role, you can eat more selenium-rich foods, such as animal liver, eggs. 3. Eat more high-vitamin foods: vitamin C and B vitamins and other vitamins have a protective effect on lung function, it is recommended to eat more grapes, grapefruit, pomelo, kiwi and other fresh fruit. The most effective way to reduce lung damage is to stay away from second-hand smoke environments. Prompt medical attention is needed when there are symptoms of lung discomfort.