After beginning of autumn, if you work in a dewy farmland for a long time in the morning, what effect will it have on your health?

Working in water for a long time, especially in very cold water, is not good for your health. This is because water is a good conductor of heat, and the human body is easy to dissipate heat in water. In order to avoid excessive heat loss, skin blood vessels will produce protective reflex, which will make skin blood vessels contract. So as soon as you enter the water, your skin becomes pale. After swimming in the water for a period of time, muscle activity makes skin blood vessels dilate, blood circulation speed up, heat increases, skin turns from white to red, and the body feels a little warm, so that people can maintain activities in the water for a period of time. If you stay in water for a long time, the heat generated by the body is lower than the heat emitted by the body in water, and the body temperature regulation function will be destroyed. At this time, the arteries in your skin will contract and the venules will expand, so that your blood will stay in the subcutaneous veins, leading to blue skin, black lips, "goose bumps" and even convulsions. In this case, you must go ashore immediately, dry the water on your body, bask in the sun, and get dressed as soon as possible after the weather is warm to prevent colds, tachycardia, muscle strain and other diseases.