Mold spores don't receive nearly the attention of the Big 3 tormentors of the allergic – grass, trees, and ragweed – but allergy experts say it's a big reason why some continue to suffer even after those seasons wind down.

For those sensitive to mold spores – not to be confused with indoor mold – the first day of Fall 2016 was a landmark day.

With the Thursday morning report, the spore count hit an all-time high of 19,990, according to the Asthma Center's Dr. Donald J. Dvorin, the official counter for the National Allergy Bureau for the last 30 years.

Consider that 7,000 – that's the number of spores that pass through a refrigerator-sized parcel of air in a 24-hour period – is considered "extreme."

Unlike the Big 3, these are spores produced by fungi, rather than pollen grains.

They typically show up in early spring and persist in the fall until the weather turns cold. The Asthma Center says the numbers are highest midsummer to late fall.

Conditions this week have been perfectly aligned for a harvest of mold spores, Dvorin said.

They love to grow on fallen leaves, of which we have plenty around here. The rains Monday might have given them a production boost, and the subequent warmth and dryness have been ideal for flight.

Inhaling the spores can trigger a reaction that apes that of inhaling tree, grass, or ragweed pollen.

The tree and grass seasons are done, and ragweed is winding down, so if you're still feeling like you're under attack from pollen, the culprit might well be a spore.

Mold spores might be the under-the-radar ugly ducklings of the allergens, but about 60 percent of Asthma Center patients who complain of grass, tree, or ragweed allergies also react to mold spores, Dvorin said.

For more on the spores and pollen, check out the Asthma Center site.