Each spring, trees release billions of tiny pollen grains into the air. When you breathe them into your nose and lungs, they can trigger an allergic reaction. Staying inside can help, especially on windy days and during the early morning hours, when pollen counts are highest. When you do head outdoors, wear glasses or sunglasses to keep pollen out of your eyes. A filter mask can help when you mow the lawn or work in the garden.
No matter what type, the truth is that up until now, no known cause has truly been pinpointed. There are many risk factors, yes, but most studies have concluded that development of cancer cells are caused by high doses of free radicals which can damage cellular structures including DNA.