From a health perspective, pollen is vital and annoying. It is an important part of plant reproduction and can give rise to things like many of the foods that people enjoy eating. However, certain forms also create an allergic reaction, usually called hay fever, which can be difficult to experience and sometimes worsens with age.
These male plant cells are analogous to things like animal sperm in their purpose because they often have to travel to create fertilization or pollination with other plant parts. This journey takes place in many ways. Wind can blow these cells away, insects pick them up and deposit them elsewhere, they can ride on animal skins, and even humans wear them in their hair and clothing.
Many people make assumptions about pollen that are not always accurate. Since some cells are larger than others, they are highly visible, and seeing this, people with allergies may assume that these are the worst allergens. Usually that is not the case. The smaller, less easily visualized cells are more likely to be easily inhaled and tend to be the biggest offenders in causing conditions like hay fever.
Another assumption is that these cells only come from one source, such as flowers, grasses, or trees. They actually come from many sources and people with hay fever can be allergic to much more than grass-based pollen, although ragweed cells are considered to be allergy-inducing. However, many people are also significantly affected by these cells produced by certain trees or flowers.
When people are allergic to pollen, what this really means is that the contact, often through inhalation of pollen cells, causes the body to produce a histamine response. Exposure to these reproductive cells creates inflammation in the mucous membranes and can lead to numerous symptoms, including a runny or itchy nose, postnasal drip, itchy eyes, occasionally asthma, cough, and others. There is usually no fever in this immune response and people may not be allergic to hay.
Hay fever can have peak seasons, when most of the pollen is present in the air. It can be difficult to avoid, although people can take medications that help reduce the response to histamine. Minimizing outdoor activities when a high cell count is reported, and making sure to wash your body and hair thoroughly after spending time outdoors, is also helpful. Since most forms of these irritant cells are microscopic, they are not likely to be seen or felt in the body. An allergic person can still tell they are present, anyway, by displaying an allergic response.
Many regions publish helpful counts for certain pollens to help people determine when an allergic response is most likely. However, many people do not know specifically which plants give them problems. Allergy testing can help determine this, and can also rule out the possibility that allergies to other substances, such as dust mites, can also cause hay fever symptoms.