Asthma usually does show up during childhood and the early adult years. Regardless at what age symptoms develop, they need to be diagnosed properly and effectively treated. Therefore, you may be referred to a pulmonary laboratory or to a specialist such as a pulmonologist or allergist for this type of testing. I do not believe that people should avoid certain foods or avoid certain areas unless there has been documented testing that would support these types of actions. In most cases, proper diagnosis will lead to appropriate treatment and good outcomes.
People are more worried about outdoor pollen counts than they are about indoor allergens.
However, to understand the impact of indoor allergens as opposed to outdoor allergens, all you need to do is think about how you use your barbeque. When we barbeque foods outdoors we will often see the smoke rise into the air. However, if someone was foolish enough to bring the barbeque into their living room and close all the windows and doors to the house, the room would quickly fill up with smoke. That's the difference in an outdoor allergen and an indoor allergen. The indoor allergen becomes a greater part of the air that we breathe as opposed to outdoor pollens that spread throughout the air.