This type of allergy refers to a pollen allergy, such as trees, weeds and grasses. Perennial allergies, on the other hand, are usually present year-round, and include allergens such as pet dander and house dust mite. Molds can be a seasonal or perennial allergy trigger.
What are Pollens?
Pollens are tiny egg-shaped powdery grains released from flowering plants, which are carried by the wind or insects, and serve to cross-pollinate other plants of the same type for reproductive purposes. When pollen is present in the air, it can land in a person's eyes, nose, lungs and skin to set up an allergic reaction. Symptoms may include allergic rhinitis (hay fever), allergic conjunctivitis (eye allergies) and allergic asthma.
Pollens that are spread by the wind are usually the main cause of seasonal allergies, while pollens that rely on insects (such as the honeybee) to be carried to other plants do not. Most plants with bright, vibrant flowers (such as roses) are insect pollinated and do not generally cause seasonal allergies since the pollen is not usually present in the air.
Pollen can travel long distances and the levels in the air can vary from day to day. The pollen level can be quite different in various areas of a particular city or area. Levels of pollen tend to be highest from early morning to mid-morning, from 5AM to 10AM.
What Causes Springtime Allergies?
Spring allergies are a result of pollen from trees, which can start pollinating anytime from January to April, depending on the climate and location. Trees that are known to cause severe allergies include oak, olive, elm, birch, ash, hickory, poplar, sycamore, maple, cypress and walnut.
In some areas of the world, some weeds will also pollinate in the springtime.
What Causes Summertime Allergies?
Grass pollen is typically the main cause of late spring and early summer allergies. Grass pollen is highest at these times, although grass may cause allergies through much of the year if someone is mowing the lawn or lying in the grass. Contact with grass can result in itching and hives in people who are allergic to grass pollen, this is called contact urticaria.
Grasses can be divided into two major classes, northern and southern grasses. Northern grasses are common in colder climates, and include timothy, rye, orchard, sweet vernal, red top and blue grasses. Southern grasses are present in warmer climates, with Bermuda grass being the major grass in this category.
What Causes Fall Allergies?
Weed pollen is the main cause of seasonal allergy in the late summer and early fall. Depending on the area of North America, these weeds include ragweed, sagebrush, pigweed, tumbleweed (Russian thistle) and cocklebur.
In some areas of the world, some trees can pollinate in the fall as well.
How Do I Know What Pollens are Present?
In most areas, pollen is measured and counted, with the different types of pollen identified. This may be reported in terms of trees, weeds and grasses, or may be further divided into the types of trees and weeds identified. Specific grasses are not usually identified on pollen counts, as grasses look the same under a microscope.
How Do I Know Which Pollens I am Allergic To?
An allergist can help determine if you have seasonal allergies, and to which types of pollens to which you are allergic. This is accomplished through allergy testing, which typically involves skin testing or a blood test (RAST). Allergy testing can be helpful in predicting the times of the year that you are likely to experience allergy symptoms, and is needed if you are interesting in taking allergy shots.
How Can I Avoid Pollen Exposure?
Unlike avoidance of pet dander and dust mites, it is more difficult to avoid exposure to pollens, since it is present in the outdoor air. Here are some tips to minimize pollen exposure:
- Keep windows closed prevent pollens from drifting into your home
- Minimize early morning activity when pollen is usually emitted-between 5-10 a.m.
- Keep your car windows closed when traveling.
- Stay indoors when the pollen count is reported to be high, and on windy days when pollen may be present in higher amounts in the air
- Take a vacation during the height of the pollen season to a more pollen-free area, such as the beach or sea.
- Avoid mowing the lawn and freshly cut grass
- Machine dry bedding and clothing. Pollen may collect in laundry if it is hung outside to dry