Fall allergies are far more complex — regionally and individually — than most people realize. Let’s explain some lesser-known nuances of allergen irritants.
Autumn Allergens Aren’t Just for Autumn
The standard acid test for allergy categorization goes something like this: if they occur year-round, they are perennial allergies prompted by indoor contaminants (such as dust mites); if they only occur in certain seasons, they are seasonal allergies prompted by outdoor contaminants (such as pollen). However, this distinction is less helpful than you might think.
One 2023 paper from the University of Naples states, “In many areas, pollens and molds are perennial allergens [...Meanwhile, some] patients sensitized to perennial allergens may not show symptoms throughout the year but only a few weeks per year.” In other words, just because your allergies are worse in the fall does not mean that they are due to fall pollen; similarly, just because you are allergic to fall-pollinating plants doesn’t mean that your allergies will only bother you in the fall.
As an additional factor of uncertainty, pollution may also make you more allergic to certain contaminants than you would normally be. The paper goes on to note that “various studies have shown that aeroallergens can become chemically modified by outdoor pollutants and aggravate allergic symptoms.”
Pollen Maps Are Unavoidable Oversimplifications
Originally, we set out to create a pollen map of the entire United States. However, after hours of research, we realized that any such map would have to be an approximation for multiple reasons. First, pollen collection stations only sample a small area, and many areas of the United States have no monitoring at all. Second, many pollen collection stations don’t operate year-round. Third, the flora in Alaska and Hawaii are so environmentally different from the rest of the United States that they don’t participate in national monitoring systems (and thus most national allergy reports don’t bother to include them).
Fall Allergies Are Caused by More Than Ragweed
The oft-repeated myth about seasonal allergies is that spring allergies are caused by trees, summer by grasses, and fall by weeds. There is a grain of truth to this: ragweed tends to pollinate late in the year; a single plant can send a billion light-weight grains soaring upon the air (and into your nostrils).
However, ragweed isn’t the only culprit. Some trees pollinate into fall or even winter. Elm trees are known to have two pollen peaks per year. Grasses and amaranths may also keep pollinating as late as December in certain climates.
In 2019, the University of Washington compiled a year-round pollen calendar for 30 North American cities. We mined their data for any plant families or genera that release pollen between August through December. Below is a full list of all 13:
| Latin Name | Common Name(s) or Examples | Number of Cities |
|---|---|---|
| Gramineae / Poaceae | Cereal Grasses | 24/30 |
| Cupressaceae | Cypress/Juniper/Cedar | 24/30 |
| Ambrosia | Ragweed | 23/30 |
| Ulmus | Elm | 19/30 |
| Amaranthaceae | Amaranth | 16/30 |
| Urticaceae | Nettle | 11/30 |
| Artemisia | (Mugwort, Sagebrush, Wormwood, etc.) | ~6/30 |
| Plantago | (Ribwort, Hoary Plantain, European Plantain, etc.) | ~5/30 |
| Pinaceae | Pine | ~4/30 |
| Cyperaceae | Sedges | ~3/30 |
| Rumex | Dock/Sorrel | ~2/30 |
| Alnus | Alder | ~2/30 |
| Asteraceae | (Daisy, Sunflowers, Mums, Asters, etc.) | Only Kansas City, MO |
You’ll notice something missing from this list: goldenrod. Most people think that these lovely fall flowers are causing their allergies, but here’s where our research busted another myth. Goldenrod pollen is too sticky to be carried on the wind like ragweed. Instead, it relies on insects and birds to spread. This doesn’t mean you can’t be allergic to goldenrod pollen if you get close and take a big sniff; it just means that the pollen is not likely to be invading your air.
It’s Not All About Pollen
The solution to pollen getting indoors is simple: an air purifier with a HEPA filter. However, pollen is not the only biological allergy trigger. Mold spores also thrive in the cool, damp autumn mists. Autumn leaves fall to the ground and collect moisture, providing the perfect habitat for mold spores to munch on. From there, they may find their way indoors, leading to sniffly noses and winter basement odors.
Mold spores are best met by a multi-pronged moisture-control effort. ActivePure’s partner SmellBusters is adept at repairing acute mold and moisture issues. As a bonus, they also will provide you with a device Powered by ActivePure® Technology that addresses mold, bacteria, viruses, and pollen. Learn more by contacting SmellBusters today.
