Harvard Health Letter

Fall allergen alert

It's not just weed pollen causing allergy symptoms; mold is also potent during autumn months.

There's more in the autumn air than just falling leaves. Ragweed pollen, mold, and other allergens are especial-ly common at this time of year. "The fall allergy season is usually the result of pollen from weeds. But after the first frost, it's all about mold," says Dr. John Dobrowski, an otolaryngologist at Harvard-affiliated Massachusetts Eye and Ear Infirmary.

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Ragweed Ragweed produces large amounts of pollen that's carried by the wind,not insects, for pollination.

Allergens

The predominant allergen in the fall is ragweed, which grows abundantly throughout the South, North, and Midwest. It has lightweight pollen with grains that can travel on the wind for hundreds of miles. Other weed aller-gens include tumbleweed, curly dock, lamb's-quarter, pigweed, sheep sorrel, and sagebrush.

Outdoor molds are another cause of fall allergies. They are in soil, com-post piles, and leaves. "Mold spores are common after the ragweed season. They are light, very small, and easily inhaled into the lungs," explains Dr. Dobrowski. Spring and summer allergies are usually related to pollen from trees and grasses.

Mold
Fallen leaves and other yard debris are breeding grounds for mold. Mold spores become airborneand are easily inhaled.

How they affect us

For some people, inhaling allergens causes the body to overreact. The im-mune system mistakes a harmless sub-stance, such as pollen, for an invader. That triggers a chain of events that makes mast cells release histamine. "Histamine allows fluid to escape from the capillaries into the tissues. This leads to the classic symp-toms of a run-ny nose and watery eyes, and sneezing," says Dr. Do-browski. This condition is known as aller-gic rhinitis, an inflammation of the mucous membranes, and it is often marked by nasal congestion and a sore throat.

Diagnosis and treatment


Tumbleweed

Before tumbleweeds dry up, break away from their roots, and roll along, they release a powerful pollen into the wind.

The symptoms of allergic rhinitis are similar to those of the common cold. "That can be confusing, but the hall-mark of allergies is clear, watery nasal drainage that lasts for six weeks, as op-posed to more yellow or green mucus for a few days," says Dr. Dobrowski.

If you're not sure what's causing your symptoms, a round of allergy testing might pinpoint the problem. This takes place in a doctor's office with either a blood test or a skin test. The latter involves introducing small amounts of allergens into the skin.

Once you know which allergens are causing your body to react, you can devel-op a plan with your doctor to manage your symptoms . Treatment can involve over-the-counter or prescription medications, or possibly allergy shots.

Top tips to avoid allergens

While you can't avoid all allergens, you can reduce your exposure to them. Try some of these steps.

  • Stay inside. Pollens are released in the morning, so people with fall allergies have greater symptoms at that time of day. Try to stay inside between 5 a.m. and 10 a.m., when pollen counts are highest.

  • Wear a face mask. If you do go outside, cover your face to cut down on the allergens you breathe in. This
    is especially helpful on windy days or when you're doing yard work.

  • Remove decaying leaves. These may harbor mold spores. Remember to wear a face mask when you remove them, or have someone else remove the leaves for you.

  • Shower frequently. It will remove pollens from your skin and hair. Rinsing the sinuses with saline spray is also helpful.

  • Change air filters. Do this in both air conditioners and heaters. Clean all vents and ducts, too. This will help eliminate allergens inside the home.

  • Keep windows closed. Apply the rule to your home and your car.

  • Have someone else do yard work. Ask a family member or friend,
    or hire someone if possible.