Allergy Season: Why It Keeps Getting Worse

More Americans than ever are finding themselves experiencing seasonal allergies, or are finding that their allergy symptoms are getting worse every year. The evidence suggests they’re not imagining it. Around the world, the intensity and duration of allergy season, as well as the rates of people affected by seasonal allergies, is increasing.

“We’re seeing a whole bunch of people who have seasonal allergies for the first time,” said Dr. Clifford Bassett, the founder and medical director of Allergy and Asthma Care of New York. “It’s the elderly and young alike, who have never had allergies before, even people in their middle-aged years.”

“So it’s on the rise,” he continued.

Struggling with seasonal allergy symptoms? Read more about the best allergy management tips and treatment options.

Part of this trend is captured by research showing that the number of people suffering from allergies generally has steadily risen over time. Quest Diagnostics released a report in 2011 which found that over a four-year period the rate of sensitization to common allergens, like the pollen that causes seasonal allergies, had grown by 5.8 percent.

In the case of ragweed pollen, a common cause of seasonal allergies, the sensitivity rate grew by 15 percent in the same period, more than any other allergen.

Allergies may seem like a relatively minor concern, but they can have profound effects on quality of life.

“During the peak season, 85 percent [of allergy sufferers] complain of fatigue, 67 percent are irritable, 60 percent are miserable, a third are depressed, and 25 percent are anxious,” said Bassett. “So there are effects on the workplace, learning, children, and productivity."

Seasonal allergies are also connected to the development asthma, which itself can be a burdensome and sometimes deadly condition.

So why are allergies getting worse? And can anything be done about it?

Climate change

There are many hypotheses attempting to explain the rise of seasonal allergy symptoms, and it seems most likely that some combination of explanations will prove to be correct.

One of the most commonly cited hypotheses is our changing climate. According to the National Centers for Environmental information, 2015 was the warmest 12-month period on record, stretching back 136 years. And the top six warmest years on record have all taken place since 1998.

What does this mean for allergy sufferers? Perhaps most noticeably, it means longer allergy seasons. As winters become warmer on average, trees have a longer period of time during which they can spread the pollen that causes symptoms. Many will noticed that the distinctive allergy symptoms of runny nose, congestion, and watery eyes have been starting earlier and earlier in the year.

The Environmental Protection Agency found that in a study of 11 locations in North America,10 have experienced extended allergy seasons since 1995. This included one area which had an allergy season that increased by nearly a month in the studied period. On average, more northern areas experienced more significant increases in the length of their allergy seasons, as the map below shows:

Mariana Castells, MD, an allergist at Brigham and Women’s Hospital, reports that the early allergy season is evident at her practice. “I have noticed this year that people have already in February and at the beginning of March started to come in complaining of allergic symptoms,” she explained.

“We have had more patients, I’d say 10 to 15 percent more, coming in at least two or three weeks earlier than we were expecting,” she continued.

But the effects of climate change on allergies don’t stop there. The increased amounts of carbon dioxide in the air associated with global warming may also cause trees and plants to thrive in new regions, which introduces people to more potential allergens than they previously would have experienced.

It also seems that a warmer climate enables plants to produce more pollen total, which raises the burden placed on sensitive immune systems and worsens symptoms. And according to Dr. Bassett, this pollen may be “super-charged” – that is, it may contain more of the protein that causes people to have allergic reactions.

The hygiene hypothesis

Increasing allergy rates, though, go back even further to a time before the effects of climate change were noticeable. Many experts believe that the modern revolution in hygienic practices – which have, in many ways, made us safer and healthier – have likely contributed to the rise of allergies.

This idea is known as the “hygiene hypothesis.” The basic idea is that our world has gotten too clean. By protecting ourselves, and especially by protecting very young children, from exposure to various contaminants, we fail to give our immune systems the ability to “learn” which foreign substances are dangerous and which are not.

Our immune systems thus overreact to non-threatening substances, which we experience as allergies.

The hygiene hypothesis implicates the overly dirt- and bacteria-adverse behaviors that are common among many overly-anxious parents. It also includes our habit of spending so much of the day indoors, especially with closed windows, which reduces our contact with the messy natural world.

One of the main pieces of evidence for this hypothesis is the fact that people in wealthy countries like the United States are more likely to have allergies and asthma. This effect is nonexistent for people who came to the United States after infancy.

“When a kid’s immune system doesn’t see a lot of germs and things like that, it gets into trouble,” Dr. Bassett explained. “It starts to think these harmless allergens like trees, grass, and dust mites are the enemy. It produces an immune system motif that is geared toward having allergies.”

Counterintuitive though it may seem, Bassett explained, children may benefit from a little lack of hygiene. “We think as adults, it’s good to use Purell and things like that,” he said. “But as kids, it’s good to be exposed to germs.”

Of course, this doesn’t mean kids should be playing in the sewers – but neither should you boil their toys every time they’re played with.

Air pollution

We also shouldn’t assume that allergies are only caused by “cleanliness,” or that allergies primarily affect wealthier people. Individuals who live in areas with more air pollution, which often includes people of lower socioeconomic status, have a greater risk of developing allergies and asthma.

“The particulate matter that is at the core of pollution seems to have an activating effect with the with the pollen and actually triggers the allergic immune cells,” Castells explained. Pollutants like car exhaust can, especially in high concentrations, exacerbate the body’s responses to allergens.

Castells pointed out that we see these evidence of these effects in the greater rates of allergies present in more heavily polluted American cities when compared to cleaner cities.

This effect also helps to explain why studies show that rural teens are less vulnerable to allergies and asthma than those that live in urban areas. Among other benefits, rural neighborhoods provide a much less polluted environment for children.

Antibiotics

Related to the hygiene hypothesis, the overuse of antibiotics may also play a role in increasing the rates of allergies.

In particular, some researchers believe that the use of antibiotics in children may affect the makeup of their intestinal bacteria, which is closely related to the immune system.

According to Castells, overuse of antibiotics, “changes the ‘microbiome,’ the bacteria that actually live in our intestine. And changing the microbiome has a tremendous impact in the way we ‘see’ the environment.”

“Some microbiomes are geared toward seeing the environment as allergic, and that has been indirectly shown to possibly be the result of overusing antibiotics,” she explained. “It changes the microbiome to bacteria that do not protect us and that permit allergens to be seen as foreign proteins that we need to fight against. “

However, the evidence for this hypothesis is mixed. While some studies have supported the theory, others that looked at the connection between antibiotic use in children and subsequent allergy development and found no connection.

Nevertheless, some preliminary studies show that some probiotics, which are strains of healthy intestinal bacteria, may serve as a treatment for seasonal allergies. This treatment method needs more research, but if it proves effective, it would be evidence that our use of antibiotics may be playing a significant role in increasing the prevalence of allergies.

Unfortunately, fighting climate change, reducing pollution, managing the overuse of antibiotics, and taking a more measured approach to hygiene and germ avoidance all require a great deal of coordinated societal effort and agreement.There are steps we could take that would likely reduce the spread of allergies in our world, but the multifaceted causes make significant progress a daunting challenge.

Photo Credit: Clara Morice via Flickr