Asthma is now the most common cause of hospitalization among American children, affecting a total of five million. Deaths among children with the condition rose by 78 percent from 1980 to 1993, according to a recent analysis. Asthma is the leading cause of missed school days for US children. Allergy-related deaths, particularly from asthma, have almost doubled every decade for the past 40 years. Females are more likely to experience pollen-related allergies than males.
Females are far more likely to have an adverse reaction to male pollen than are males.
Pollen is overwhelmingly local. In the case of plant or pollen allergies, the fewer allergenic plants in an individual's immediate vicinity, the less the chance of exposure, because the great majority of windborne pollen grains of all species are deposited quite close to their source. A pollen-producing tree or shrub next to a home can create ten times more exposure than a tree or shrub one or more houses away. For most grasses or other herbaceous plants, dispersal is still more concentrated with most pollen falling within a few meters of the host plant. Prevention in the garden and landscape makes sense.