As part of the wider trend of milder European winters, December pollen is troubling asthma sufferers as far north as Scandinavia.

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This has led to a huge rise in allergens and pollen in the air, which can trigger asthma attacks.

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"People who are diagnosed with asthma that is made worse by pollen and people who have been diagnosed with seasonal allergic rhinitis need to keep track of pollen and other outdoor allergen levels, " says Dr. William Lunn, the director of the interventional pulmonary service at Baylor College of Medicine, in Houston.

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Research presented at the American College of Allergy, Asthma and Immunology in November suggests that pollen counts are going to get a lot worse in the next 30 years.

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About 60% of the 17 million U.S. asthma sufferers are allergic asthmatics, meaning that their asthma attacks can be triggered by allergic reactions to pollen, dust or other normally harmless substances.

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Allergies to pollen, furry or feathery animals or house-dust mite, can be triggers for asthma, because they irritate the airways.

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IgE can mistake harmless specks of pollen or dust as dangerous invaders and start biochemical chain reactions leading to nasty allergy or asthma attacks.

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Not only is the pollen apocalypse on its way, three of the state's major cities made the Asthma and Allergy Foundation's annual list of the 10 worst places for spring allergy sufferers.

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