Ragweed season is underway in Philly, and it’s about to get worse for allergy sufferers

For allergy sufferers the summer break is ending, and any day now hundreds of thousands of them may wake up sneezing or rubbing their eyes, or both.

So much of the intensity of the ragweed season, which peaks in September, depends on the abundance of the crop — which is unpredictable — and the daily weather. Need we say more?

But, “no matter how you slice it, it’s going to be bad for people,” said Manav N. Segal, an allergist in private practice with Chestnut Hill Allergy and Asthma Associates.

» READ MORE: As pollen torments millions, it might be getting worse, and it’s poorly measured in America

What’s more, he said, with worldwide warming and the delay in the arrival of autumnal chill, the seasons are getting longer. “Ragweed pollen levels don’t start coming down until temperatures start coming down,” he said.

Added Marc Goldstein, an allergist with the Asthma Center, in Center City, pollen may remain at irritating levels “through early to mid-October.”

» READ MORE: Pollen season peaked in mid-September last year. It does have predictable rhythms

If nothing else, ragweed, a homely, tooth-leafed member of the Ambrosia family, is aptly named. It grows all over the country.

It doesn’t need a landscape service to propagate. It’s perfectly happy among roadside detritus. And does it ever reproduce; pollen emissions are the key to that process.

» READ MORE: The secret life of pollen: It can solve crimes

“Individual plants produce tons of pollen, like a billion particles per plant,” said Segal.

Those particles are inhaled without incident among the majority of the population, but the immune systems of allergy sufferers treat the pollen as an invader, tormenting their bodies with mind-numbing spells of sneezing and eye irritation.

The Environmental Protection Agency estimates that ragweed irritates more than 50 million Americans.

Plants have been pollinating for eons, yet the history of pollen allergy is primarily a modern saga.

It was not until the late 19th century that pollen was identified as the cause of the misery. Two researchers figured it out the hard way. By inhaling ragweed pollen deliberately, Morrill Wyman, a Massachusetts physician, proved the connection.

In an 1875 paper, he succinctly described the ragweed season, writing that it “sets in toward the end of August as surely as swallows come in spring.”

In an exhaustive treatise published a few years later, English researcher Charles H. Blackley, a 20-year allergy sufferer, recounted a sneezing fit when a passing carriage stirred up a cloud of dust.

Blackley returned to the spot the next day and stirred up a pile of dust, with the same results. Examining some of the particles, he “easily” recognized pollen grains. He went on to conduct experiments on himself, inhaling more pollen and rubbing it in his eyes.

Blackley surmised that pollen grains were so light that they could travel for hundreds of miles on air currents.

For reasons that remain unclear, the incidence of ragweed symptoms evidently increased tremendously during the first half of the 20th century, when cities grew rapidly. Researchers have found urban residents appear to be more pollen-sensitive than their rural counterparts, who may have built immunity through more contact with plants.

Whatever the cause, ragweed had become such a problem in New York City that city council declared war on it in 1948.

It didn’t go well.

Health Department officials had hoped to eradicate all the ragweed in the five boroughs with herbicide. But after nine years, ragweed numbers were down only about 50%, according to a study published in 1956.

What’s more, “By all criteria the effects of Operation Ragweed on the city’s pollen index are not striking,” the authors concluded.

For one thing, the tenacious weed “grows naturally and profusely,” in New York, they said. Plus, perhaps more significantly, much of New York’s pollen is imported on west winds from Pennsylvania and New Jersey. One reason why people can have sneezing attacks on a Jersey beach.

Pollen flight is all about the winds, and those are dicey to forecast more than a few days in advance.

Rain is the sufferer’s friend, since it dampens pollen flight. The lengthening growing seasons associated with climate change and increased precipitation argue for more robust pollen harvests. But the rain cuts both ways.

“If there is lots of rain during the pollen season,” said Estelle Levitin, an aerobiologist and emeritus professor at Tulsa University, “you get washout and the pollen season seems less intense.”

The antecedent conditions also are critical. Donald Dvorin, with the Allergy and Asthma Doctors in Mount Laurel and the region’s only certified pollen counter, says that this year they are hard to read. It is unclear whether the general wetness that took hold in mid-June has countered the spring dryness.

Andrew Frankenfield, agronomy educator at the Penn State agricultural extension in Montgomery County, says he is betting on the recent wetness to give the crop a boost. Ragweed will have its days, he said: “Don’t expect it to disappoint.”

» READ MORE: First freezes in Philly have been occurring later in the fall in recent years

Along with medications, doctors advise limiting outdoor time on dry, breezy days when counts are high. Segal says counts typically peak in the early morning.

It doesn’t hurt to wear masks outside, nor to shower and change clothes when back inside. Also, keep the windows closed if possible.

Daily counts are posted by Center City’s Asthma Center, which uses an automated system, between 6 and 7 a.m. Dvorin’s counts, based on a 24-hour sample of what has been captured in his Mount Laurel trap, are available on afternoons Tuesday through Friday.