I believe it is due to the amount of pollutants that are in the world. Not only are there increasing amounts of pollutants in the air but we are discovering more and more compound that people are allergic to. Another thing that adds to this number is due to genetics. As more and more generations form there is more of a chance that somewhere in there genetics is a suseptibility to an allergen.
Yes, the increase in allergy sufferers has a definite cause. This is the increased amount of time that people spend indoors, particularly as children. Because they do not have time to build up a resistance to those allergens, when they do go outside, they have more of a reaction than our ancestors did.
All the people above me I believe are correct but I also believe there is more than one reason. With today's science people with health conditions are living longer and living in General, when they have kids they pass on their genes. Back then if people had health problems they died and didn't pass on weak genes. Allergies might not seem dangerous today because of the medication we have today but allergies can kill
I believe there is a reason people suffer more from allergic reactions today. I believe the main culprit is our standard of living. Everything is clean and we try to keep it that way. I think by doing this we expose our immune system to less and that eventually ends up causing problems such as more allergic reactions.
The rise of pollution in the air, as well as other factors, such as smoking, may have a lot to do with more people suffering from allergic reactions. Also, there are more new products and chemicals and things being produced that could trigger allergic reactions in people today. The way people live today is different.
The "clean world" hypothesis simply states that excessive cleanliness prized in today's home and school environments interrupts the normal development of the human immune system, and this interruption leads to an increase in detectable allergies. In other words because we are cleaner our bodies don't get the chance to develop antibodies to normal items in our community.