The polen grains in this plant causes asthama in man

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Explanation:

Tree pollen is a common hay fever trigger. It’s the first pollen to be released during hay fever season, and levels are typically highest from late March to mid-May.

Around 95% of people’s hay fever is triggered by grass pollen, which tends to be highest between mid-May and July. In fact, there’s strong evidence that when grass pollen levels are high, people with asthma are more likely to need hospital treatment.

Hay fever can also be triggered by weed pollen, which is highest from the end of June until September.

Know your pollen triggers

You can be allergic to more than one kind of pollen across the year. Different pollens are released at different times, but our changeable weather makes it hard to predict exactly when. If you have hay fever symptoms all year round you might have non-allergic rhinitis.  

If you regularly get hay fever and take antihistamines, start taking them up to four weeks before you normally get symptoms. Starting them early means that when pollen starts being released, the medication has already built up in your bloodstream so you may be less likely to react.

If you usually use a steroid nasal spray, it can take up to two weeks to start working, so again, start using it before your personal pollen trigger is released.

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