St. Louis Allergy Index

Pollen Allergy in St. Louis

Pollen allergy Pollen allergy is the primary cause of seasonal allergic rhinitis, although mold is present in the outdoor air at the same times of year. The single most important measure to minimize pollen exposure is to keep the windows closed and use air conditioning during the warm weather months.

Tree pollen is in the air in the Spring months, often beginning in late February with maple, elm, and juniper (red cedar) and extending through March and April into May. The yellow or green dust we see on our cars in the Spring is tree pollen.

Grass pollen is present when grasses pollinate in the late Spring and early Summer, approximately from May 15th to July 15th.  Cutting the grass stirs up grass pollen, particularly when the ground is dry.

Ragweed and other weeds pollinate in the late Summer & Fall, from August 15th through the first frost. This is also the time of year of the highest mold counts.

Mold Allergy

Mold allergy molds are organisms that propagate by forming microscopic spores that become airborne. Other names for molds include fungi and mildew. There are both outdoor and indoor sources of mold spores, so measure to avoid both indoor and outdoor mold should be undertaken.

Mold spores are present in the air in this area from Spring through the Summer until the hard frost in the late Fall, with highest counts in the late Summer and Fall. Keeping windows closed throughout the warm weather months, including in mild weather in the Spring and Fall, is the most effective measure to avoid outdoor mold.

Fallen leaves, grass clippings, and compost piles, all being dead vegetation, support heavy mold growth. Raking leaves or cutting grass is not a good idea for the mold-allergic patient. If one must do these activities, wearing a mask and taking an antihistamine before these activities may help minimize symptoms.

All damp, musty-smelling areas are sources of mold exposure. Examples would include damp basements, barns, cabins, and caves. Basements, even if they seem dry will generally contain more mold than an upstairs room of the same house. Basements are therefore not good locations for bedrooms of mold-allergic patients.  A dehumidifier in the basement can help retard mold growth by keeping the air drier. Mold-retarding paints and paint additives are available at hardware stores to reduce mold growth on basement walls.

In the home, furniture, pillows, mattresses and stuffed toys are potential sources of mold. Feather and foam rubber pillows should especially be avoided since both tend to support mold growth. Even polyester pillows, however, should be encased in dust-proof covers. Molds can be found in rubber door gaskets and drip trays of refrigerators, in shower stalls, or on damp walls and ceilings. Various mold-killing products, generally containing bleach, are available to clean these surfaces.

Vaporizers or room humidifiers should not be used long-term (for weeks or months) for two reasons. First, the vaporizer itself can become contaminated with mold, and, secondly, the room can become overly humid and this can encourage mold growth.  Short-term use (a few days) of a vaporizer if acceptable if the device is emptied and dried out daily and cleaned every couple of days with dilute bleach. An efficient furnace humidifier (without a reservoir) is often helpful to the allergic patient in the Winter and generally will not increase mold growth. Ideal humidity is 30 - 45%.

Air conditioning helps the patient both filtering mold from the air and by dehumidifying the indoor air. Air conditioning should continue from the Spring through the late Fall.

Maple, Juniper and Elm Trees are known to be the top 3 pollen trees that can affect your allergies.


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