Our body can be affected easily if the temperature of a room changes suddenly. So, this affects our health, too. Unfortunately, people are facing a hotter future because of global warming day by day. Especially in summer, after a hard and hot day, we come home. And we turn on our air-conditioners to feel relaxed. Air-conditioners are very useful devices for our health as long as we use them properly. If not, they can be harmful. For instance, if you expose to cold air when your body is hot, you feel pains on your head, neck and shoulders. Maybe you can get flu or sore throat. An air-conditioner user shouldn’t sit in front of an air-conditioner or cold air. And we should change the temperature decreasingly or increasingly. And try to use your air-conditioner with wind flaps which distribute cold/hot air into the room in different aspects. Most scientists believe that normal temperature in a room must be from 22 to 25 centigrade degrees. Other important rule is to clean and sterilize the air-conditioner and particularly filters. A disease called “humidifier fever” results from air which comes from a dirty and dusty air-conditioner.