Allergic asthma is commonly caused by inhaling fumes, smoke, dust, pollen, molds, and dust mites. Approximately 50 percent of adults and 90 percent of children have allergies and asthma. Other things affect asthma, such as exercise and cold air. If you have asthma, you should use your inhaler before exercise, and then listen to your body. If you begin to feel your chest tightening, or you can hear yourself wheeze, you need to stop exercising. If you live in a cold climate, you should wear a scarf around your mouth and nose to help warm the air before it hits your lungs. If you are outside, you should not breathe through your mouth, because this will likely bring on an asthma attack. It is not uncommon to start coughing as soon as cold air hits your bronchial tubes and lungs. The bronchioles often go into bronchospasms when cold air hits them. No one really knows what causes asthma, but for much of the population, allergies play a big role. The immune system protects the body by attacking bacteria and viruses to keep the body healthy. The Immunoglobulin E (Ig E) part of the immune system overreacts and mistakes harmless substances, like pollen, dog dander, and cat dander as harmful invaders. The immune system can't tell cat dander apart from disease causing bacteria and viruses. The Ig E part of the immune system triggers other parts of the immune system to release histamine. Histamine tries to get rid of the invaders, and block new ones from coming into the body by causing an allergic response; this is why you get the runny nose or stuffy nose, watery eyes, coughing, wheezing and chest tightening. The wheezing and chest tightening is caused by bronchospasms. A mask won't help you prevent allergy and asthma symptoms, because the particles can be inhaled right through the mask.