[Pollen environment and its evaluation]

We review the methods available for determining airborne pollen. In addition to the classical gravimetric and volumetric methods, new immunochemical techniques are also used for detecting allergenic pollen and measuring of the size of allergen-carrying particles. Pollen counts are available in France for 39 urban sites. In the last decade changes in the pollen environment have basically concerned higher counts from resinous trees in southern France and birch tree counts in northern France as well as a lesser role for ash trees. Among the recent acquisitions, it has been demonstrated that allergens are present in twigs and leaves, or even the bark of certain trees. Interactions with atmospheric pollution is better understood and could be a contributing factor to the increasing number of people allergic to pollen. Pollen allergens can be carried on particles of various sizes and immunochemical studies have demonstrated that gramineous pollen allergens can be carried on starch particles less than 3 mu in diameter. These recent studies would explain the apparent disagreement between pollen counts and the number of clinical manifestations.