Indeed, pollen concentrations are often lower in coastal areas. This is indeed the case for tree pollen. A stay at the seaside when birch trees are flowering (April-May) is recommended to individuals sensitised to birch pollen.

However the rule does not apply to grass pollen. The influence of wind directions plays a role on pollen concentrations in the atmosphere. Densities are low in case of sea winds whereas with inland winds, pollen densities may be as high as inside the country. This is why hayfever sufferers (sensitised to grass pollen) do not necessarily feel relieved at the seaside.