The spring allergy capitals are based on tree pollen counts, while the fall cities are ranked on ragweed pollen counts from September through November of the previous years.

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While people are tempted to say they have spring tree pollen allergies, it is helpful to know the exact types of trees you are sensitive to -- that way you can watch the pollen counts more efficiently.

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"If you have a choice to plan an outdoor event versus an indoor event, people with spring allergies, who have tree pollen allergies, would be better off choosing indoor activities during the peak pollen season, " he said.

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Dr Hume said the team had also found thousands of leaves, wood, pollen, tree and shrub seeds including the famous dodo tree (Tambalacoque), plus a large number of small land snails and insect parts.

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Pollen particles are "so small, even if you're not sitting under a tree or anything, you're going to get large amounts of pollen that could be blown from miles away, " Mr. Robinson said.

WSJ: Sniff, Sneeze, Blow, Wipe, Repeat