CHICAGO -- Fall is in the air. Chicago evenings have a crisp breeze. But something has been bugging Annie Andrews.

Specifically, bees and wasps and a whole lot of sneezing.

“It’s gotten to a point, like, I couldn’t stop sneezing during a shift,” said the 28-year-old restaurant server. Earlier this week, she thought, “I need to take an allergy pill again.” When she waits tables outside, the insects swarm patrons, who desperately ask her to be moved elsewhere, anywhere the bees and the wasps aren’t.

Chicagoans from all over can likely relate. Pollen has concentrated in the city over the past three weeks, mostly from ragweed. Wednesday counts were the highest recorded so far this year — the last time the area had so much ragweed was in 2018, according to Loyola Medicine.

Allergy season is getting worse, climate science nonprofit Climate Central reports. And shorter winters are contributing to more days with high pollen counts and buzzing insects that can derail residents’ hopes for peaceful patio dining.

A warmer, earlier spring and a later fall frost are lengthening the growing season for plants, giving them more time to release allergy-inducing pollen earlier in the year and for longer. Plant-based allergies in the U.S. come from tree pollen in spring, grass pollen in early summer and weed pollen in summer and fall.

In Chicago, the time between the last spring freeze and the first fall freeze has increased by an average of 21 days since 1970.

“And it’s not just in Chicago,” said Andrew Rorie, associate professor at the University of Nebraska Medical Center Division of Allergy and Immunology. “Study after study all around the world (is) showing that, generally, pollen season is lengthening.”

Over the last 55 years, the number of so-called freeze-free days has increased by an average of 20 days in 172 of 198 U.S. cities, according to data from the National Oceanic and Atmospheric Administration analyzed by Climate Central.

Not only is the season lengthening, Rorie said, but more pollen is being produced throughout, and the number of peak days — when pollen counts are at their highest — is also increasing.

In the Chicago area, ragweed counts have been unusually high this year, according to Rachna Shah, lead of Loyola Medicine’s Allergy Count. She gathers samples every weekday morning between March and October from the roof of a hospital in Melrose Park, then counts spores and grains under a microscope.

On Wednesday, Shah tallied 148 grains of pollen per cubic meter of air. Any number between 50 and 500 is considered a high count. Earlier in the season, it would take her some 15 to 20 minutes to count — lately, it takes her closer to an hour or an hour and a half.

“This is actually a pattern. For the past month, essentially, I’ve been reporting: Ragweed is high. Ragweed is high,” Shah said. “This year, symptomatically, I’m just seeing a lot more (patients).”

Seasonal pollen symptoms — such as a runny or stuffy nose, itchy or swollen eyes, sneezing and coughing, and trouble breathing — can be inconvenient. But they have very real, daily implications for millions of people in the United States, plaguing 1 in 5 children and 1 in 4 adults, according to the Centers for Disease Control and Prevention. Prolonged exposure for people who are susceptible to asthma attacks is also increasing emergency room visits.

“It is really tempting, as the mornings and evenings cool off, to open up the windows and open the house a little bit. That lets all that pollen indoors,” Rorie said.

Most of the allergenic product comes from “boring-looking plants,” Rorie said, which rely on the wind to carry their pollen to reproduce. But just like their growing season is lengthening, so is that of pretty flowers that insects — like bees and, to a lesser extent, wasps like yellow jackets — pollinate, meaning they are active earlier and later in the year.

Outdoor activities in the early fall not only expose people to pollen that can cause allergies, but also to some confused insects.

“They become just a little bit more perturbed and a little more aggressive because they’re kind of running out of food,” Rorie said.

Studies have directly linked higher levels of planet-warming carbon dioxide to a boost in pollen production in plants such as grasses and ragweed. Shah said recent high counts of ragweed can also be connected to the abnormally dry, mild weather for this time of year.

“We’ve had some rain and we’ve had some storms, but we haven’t had a lot. Rain breaks down pollen,” she said. “We’ve also had either mild temperatures or, next week, it’s going to get a little higher.”

It’s the perfect combination for ragweed to bloom, Shah said.

If there is no reduction in human emissions of heat-trapping gases, the United States could face up to a 200% increase in pollen production by the end of this century, according to a 2022 study.

“We’re always looking for evidence about what’s happening with climate change,” Rorie said, “and when we can find really hard, objective evidence that there’s something changing that’s directly impacting our health, I think it’s important to really take note. And this is certainly an example.”

Bees love flowers, wasps love trash

Andrews has been waiting tables at a Lincoln Park restaurant for six years. In recent weeks, yellow jackets and bees have been swarming patrons eating on the patio. The former are gunning for food and leftovers; the latter, for the real flowers that beautify the space.

There’s no easy solution, though: “You either have to share your meal — make (the insects) an offering — or just sit inside,” she said.

She doesn’t remember it being as much of an issue in her first few summers.

“As it stays warmer longer, they definitely (stay out) longer,” Andrews said. “So they’ve been more of a problem into, like, October. I even feel like I notice them showing up earlier, too, especially these past couple of years.”

To the untrained eye, bees and wasps all look the same: like small, buzzing blurs of black and yellow.

“I find that people have a lot of trouble distinguishing a yellow jacket from a bee, and they’re biologically really different,” said Alan Molumby, associate professor and director of prairie biological science at the University of Illinois Urbana-Champaign. “Let’s just say, in terms of evolutionary classification, a bee and a yellow jacket are about as different from each other as a rhino and a tiger.”

While bees typically don’t sting unprovoked, yellow jackets often do.

“So if you’re out on the patio trying to have some food and cocktails, those are the ones that are problems,” Rorie said.

Most yellow jackets in the city are one of three species: German, common or western. All three are invasive.

“They’re Old World, but they’ve spread everywhere,” Molumby said, “because they have made an ecological jump. It happens only a few times in evolutionary history.”

That is, they’re one of the few animals — like raccoons and rats — that have evolved to survive on human garbage.

“It’s the reason why they’re hunting at your barbecue looking for salami, they’re hunting for your Coke can, because we provide ideal resources for them,” he said.

At this time of year, the queen of the colony is also focused on producing more males and new queens — and the worker yellow jackets are close to the end of their lives.

“They have absolutely no purpose whatsoever,” Molumby said. “So this period of time, there are confused workers flying around with no real function.”

Most of them die by the first frost.

On the other hand, honeybees can overwinter, hunkering down in their colony and feeding off honey when it’s too cold for flowers to grow and offer them nectar. When it’s warm and flowers abound, that’s where they go. Even when they are potted in restaurant patios.

Besides yellow jackets, which scavenge for food and prey on other insects, other wasps are important pollinators, like bees.

“People are going to have irrational expectations because they don’t understand them,” Molumby said. “If you’re anywhere near flowers, you’re going to get bees and wasps. The only way to avoid it is if you … buy the most boring, soulless flowers you can get.”

Pollen and pollution

Each spring, yellow dandelions sprout all over in green spaces across the city. While they are considered weeds, the Chicago Park District avoids spraying pesticides to control them in 90% of public parks.

The practice allows grasses to grow strong roots and access water deep underground, making them grow tall and naturally shade out certain weeds. Dandelions are managed naturally with scheduled mowing. They also don’t cause a lot of allergies in humans because of the way their pollen is dispersed.

Dandelions and other flowering plants, such as tulips and roses, are showier to attract insects that will help carry their pollen far away. Honeybees see bright, fragrant dandelions and will pollinate them, Rorie said.

Because pretty plants don’t rely on the wind for dispersal — rather, they stick to the legs of pollinators like bees and butterflies — there is not much of their pollen floating in the air.

On the other hand, ragweed, oak trees, grasses and other plants that produce allergens are mostly wind-pollinated, which means they produce large quantities of light, small pollen grains that can be easily picked up by air currents — increasing the chances that people will inhale them.

In addition, people are experiencing more strain on their respiratory systems because of worsening air quality due to pollutants like ground-level ozone and small particulate matter.

It’s a double whammy to public health, Rorie said.

“Not only does it look like maybe it’s making some pollen more allergenic, but that poor air quality has a detrimental effect directly on our airways, and causes a lot of inflammatory airway disorders,” he said. “So those airways become more inflamed, and then on top of it, (they’re) getting hit with possibly more allergenic pollen.”

And no one is really safe forever. People can develop allergies anytime, Rorie said. He has patients in their 60s and 70s who suddenly became allergic to a certain food or medication, to ragweed, or to cats or dogs.

“It can happen at any point, and we don’t really understand what flips that switch,” he said. “We can certainly see more people become sensitized to some of these pollens, including ragweed.”

Widely considered the worst and most common pollen allergen, ragweed is the main culprit of symptoms between late July or early August and early fall. Most plants often continue producing pollen until the first frost. A single ragweed plant can release up to 1 billion grains of pollen that can be carried long distances by the wind.

“This is a bad time of year for allergy sufferers all over,” Rorie said.

Ragweed also thrives in urbanized areas; a 2003 study found that the urban heat island effect — when gray buildings and a lack of green space in cities trap high temperatures, amplifying heat — causes ragweed to grow faster and produce more pollen.

Pollen can trigger asthma, which affects 6.5% of children across the United States. And allergic asthma is the most common type. Black and Puerto Rican children are between two and three times more likely to have asthma than white children, and thus more at risk for allergic asthma, according to the Asthma and Allergy Foundation of America.

The U.S. Environmental Protection Agency published a report in 2023 that found 3.6 degrees Fahrenheit of global warming could increase asthma-related emergency room visits among children by 17% annually from exposure to oak, birch and grass pollen.

And younger generations, already exposed to allergy seasons that are intensifying due to climate change, will experience more warming and thus exponential effects on their health.

What to do

Short of reducing greenhouse gas emissions that warm the planet and increase pollen production, people can take certain steps to respond to longer, worse allergy seasons.

Rorie suggested taking “basic avoidance measures, if at all possible.” That includes keeping windows at home and in vehicles closed and running air filters in indoor living spaces.

People can check daily air quality and allergen forecasts before heading outside as well. Daily counts can be found on the Loyola Medicine website, and residents can sign up for notifications from the American Academy of Asthma, Allergy and Immunology, which uses Shah’s reports to the National Allergy Bureau.

After spending time outside on days with particularly high counts, Rorie said people should shower to rinse off pollen and do nasal irrigation to clean their mucous membranes. Over-the-counter allergy medication can also be useful.

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