Aerobiology of common environmental allergens: sizes of allergen carrying particles.

There is increasing evidence that environmental inhalatory aller­ gens are not exclusively carried in the atmosphere by so-called primary allergen carriers, such as mite faecal balls, pollen grains, etc., of relatively big aerodynamic sizes, but also by secondary allergen carriers, mostly of (much) smaller dimensions. This evidence is illustrated by three exam­ ples of common environmental allergens, at least in most of the moderate climate zones of the world: products of mites, of cats, and of grasses. In other climate zones the allergen sources may sometimes be different, but the principles are the same.