Fog is not suitable for exercise. In foggy days, pollutants combine with water vapor in the air, which makes it difficult to spread and settle, making most pollutants gather at the height where people often move. Moreover, some harmful substances will become more toxic when combined with water vapor, such as sulfur dioxide becoming sulfuric acid or sulfite, chlorine hydrolyzing into hydrogen chloride or hypochlorous acid, and fluoride hydrolyzing into hydrogen fluoride. So the air pollution in foggy days is much more serious than usual. In addition, the particles that make up the fog core are easy to be inhaled and stay in the human body, and the air inhaled during exercise is much more than usual, which aggravates the harm of harmful substances to the human body. In a word, the harm of foggy exercise to the body is greater than the benefit of exercise. Therefore, it is not suitable for exercise in foggy days. Fog is a very unclean thing. According to analysis, fog beads contain many harmful substances such as acid, alkali, salt, amine, benzene and phenol. At the same time, some dust, pathogenic microorganisms and parasitic eggs are not attached. Therefore, when there is fog, it shows that the whole atmosphere is relatively stable, the atmospheric disturbance is small, the air convection is weak, impurities are not easy to spread outward, and more harmful substances are accumulated in the air. It can be seen that air pollution in foggy days is more serious in cities than in other places. If you exercise in the fog, take a deep breath in the fog for a long time or be attacked by the fog, it is easy to cause rhinitis, laryngitis, tracheitis, conjunctivitis and other diseases. Because there are many water droplets in the fog, it will affect the normal exchange of gas in the lungs and make the body lack oxygen, so it feels chest tightness and produces adverse reactions such as oppression and physical weakness. Therefore, from the perspective of health care, if you exercise in a place that is not conducive to air diffusion and serious air pollution, it should be said that it is not worth the candle. Therefore, people who like morning exercises are advised not to exercise in foggy days. In addition, attention should also be paid to the air environmental monitoring quality report issued by relevant departments. Where the air pollution index is greater than 100, it belongs to mild air pollution and is not suitable for outdoor sports.