Allergic rhinitis: The chronic disease society underestimates

One in three people in Western countries lives with allergic rhinitis, yet it is rarely taken as seriously as it deserves. In this interview, Dr. Ibon Eguiluz, an allergologist and ClimAIr researcher, explains why this disease ranks at the top of the social cost rankings, how air pollution and climate change are worsening it, and how the ClimAIr project is developing tools to predict and manage its impact.

When people think of allergies, they often picture a few sneezy weeks in spring. But according to Dr. Ibon Eguiluz, a specialist in allergology and one of the researchers involved in the EU-funded ClimAIr project, allergic rhinitis is a serious, chronic condition with profound consequences for individuals and society, and it is getting worse.

A disease that follows you through life

Allergic rhinitis affects between a quarter and a third of the population in Western countries, with rates reaching up to 40% in highly industrialized societies. Unlike conditions such as diabetes or hypertension, which typically emerge later in life, allergic rhinitis usually appears in childhood and accompanies the individual throughout life, through school and work, and often into old age.

"It doesn't kill you," Dr. Eguiluz acknowledges, "but if you estimate the indirect costs of chronic diseases to society, particularly the loss of productivity, allergic rhinitis is probably at the top of the list."

In children, the condition is linked to poorer academic performance. In adults, it translates into reduced workplace productivity, a phenomenon known as presenteeism: being physically present but unable to perform at full capacity. This, Dr. Eguiluz explains, is the disease's greatest social burden. "It is clearly linked to greater school failure in children, which has significant repercussions, both social and personal, on the life options available to that person."

What allergic rhinitis actually does to you

The four cardinal symptoms of the condition are: nasal discharge (which can run forward or drip down the throat), nasal itching, sneezing, and nasal congestion. These may sound manageable in isolation, but in practice, they can be deeply disruptive.

"Everything that requires concentration becomes very difficult," Dr. Eguiluz explains. Driving, studying, and working are all seriously affected. Allergic conjunctivitis, which frequently accompanies rhinitis when the trigger is pollen or animal epithelium, adds a further layer of disability. "If you have significant allergic conjunctivitis, you cannot even see properly. You cannot drive, you cannot read, and if you rub your eyes a lot, they end up hurting." Dr. Eguiluz is clear that conjunctivitis can be as disabling as the nasal symptoms themselves, or more so.

night, severe nasal congestion leads to another problem. "When you have a lot of nasal congestion, you usually end up with post-nasal drip. That irritates the throat a great deal and prevents you from sleeping, so it is also an important cause of sleep-onset insomnia."

The disease rarely appears alone. It is commonly associated with asthma, atopic dermatitis, and food allergies. And crucially, it tends to worsen over time: a person who starts out allergic to one thing often becomes allergic to many, and someone who began with rhinitis alone may eventually develop asthma. "It does not stay stable. One tends to become allergic to more and more things, usually starting with one allergen in childhood, and ending up being allergic to many. And perhaps at first there was no asthma, and later there is."

Climate change and pollution: A worsening picture

Allergic rhinitis is, by its very nature, an environmentally driven disease. It is caused by the immune system developing antibodies against airborne allergens, such as pollen, dust mites, or mould spores. But both air pollution and climate change are worsening the situation significantly.

Outdoor pollution, particles, ozone, and other compounds from traffic and industry damage the nasal mucosa, making it more permeable and allowing allergens to penetrate more deeply and trigger stronger inflammatory responses. Beyond this direct irritation, pollution acts on the allergens themselves. "Pollution not only affects human beings," Dr. Eguiluz explains, "it also acts on the allergens themselves. Nitrogen oxides, a pollutant derived from industry, modify pollen allergens and make them more allergenic, meaning they have a greater potential to sensitize individuals who are not yet sensitised." The overall effect is twofold: "Pollution makes our airways worse and makes ordinary allergens even more potent."

Climate change adds further complexity. Rising temperatures are extending the pollen season. "Someone who used to have symptoms for a few months of the year now has them all year round, or the symptoms are more intense because the quantity of allergens is greater." Warmer, more humid conditions also favor the growth of dust mites and molds. And as ecological niches shift, new allergenic species are colonizing regions where they were previously unknown. Ragweed (Ambrosia) is the clearest example: "Twenty years ago, in areas like Romania and Bulgaria, southeastern Europe, there was no ragweed pollen. Now those areas are completely colonised by ragweed, because the temperature change has allowed it to grow where it could not before."

Extreme weather events bring additional risks. Flooding promotes mould growth in homes, exposing occupants to fungal allergens and mycotoxins. And there is the phenomenon known as thunderstorm asthma: "When there are thunderstorms, a very special set of barometric pressure conditions is created. These sudden changes cause pollen grains to burst, all at once, in the small geographic area where the storm is. This generates very small particles that can reach much further down into the airways, producing sudden, localised epidemics of visits to emergency departments for bronchospasm, like an asthma attack, and even deaths."

The ClimAIr Project: Building a predictive tool

It is precisely this intersection of climate, pollution, and allergic disease that the ClimAIr project seeks to understand and, ultimately, to predict.

The project brings together researchers from 9 European countries, clinicians, immunologists, engineers, environmental scientists, meteorologists, and science communicators, to collect and analyze data at a scale that would be impossible at the national level.

The consortium's participating health centers are focusing on allergic rhinitis, chosen both for its prevalence and for practical reasons of research viability. "We chose rhinitis for its prevalence and its universal distribution, with similar rates across all the countries participating in the consortium," Dr. Eguiluz explains. Asthma, though perhaps appearing more serious at first glance, is harder to diagnose objectively, which matters enormously for a research study. "Confirming it with an objective test, which is what you need for a research study, is not straightforward, especially in mild asthma cases, which are the ones we would have recruited, because they do not show sufficient loss of lung volume to diagnose with certainty."

The project is specifically studying pollen allergies: olive pollen in the Mediterranean region, grass pollen in Western Europe, and birch pollen in the north and northeast of the continent. From each patient, a blood sample and a nasal wash will be collected, on which participating centers will perform what are known as omics studies: epigenomics, transcriptomics, proteomics, and metabolomics. All of this will then be correlated with clinical data: the number of flare-ups, medication use, and quality of life.

The goal is a clinical decision-support tool that, given a patient's location, their pollution exposure, and predicted climate conditions, can estimate their risk of experiencing more severe symptoms. "The tool will be able to predict, for an individual in a given location, knowing the pollution levels and being able to roughly forecast the climate in that area, what risk they have of experiencing more or less severe rhinitis, and how much medication they are likely to need." This has practical implications for daily life: "When people do outdoor sport or go for a picnic, there can be a huge difference in symptoms from one day to the next. The tool can help them avoid the moments when they are likely to have the most problems."

But the tool also has clinical implications. "Identifying the patients who are going to get worse is important, because you can offer them a curative treatment, allergen immunotherapy, which, above all, prevents this progression." Without it, standard treatments fall short: antihistamines, nasal sprays, and eye drops control symptoms but do not address the underlying cause of the disease or prevent progression. Allergen immunotherapy, by contrast, addresses the root cause and can prevent patients from developing new sensitivities and, eventually, from progressing to asthma.

Why projects like ClimAIr drive meaningful change

For Dr. Eguiluz, one of the greatest values of ClimAIr lies not just in its scientific outputs but in the very structure of the consortium itself.

"In national projects, you tend to work with people who do similar things to you," he reflects. "What is unique about this type of European Research and Innovation Action is that it brings together professionals you would never otherwise encounter: engineers in chemistry, industry, and telecommunications; environmental scientists and meteorologists; bioethicists; science communicators. That interdisciplinary contact is what makes it genuinely different."

And it comes with resources to match. "Developing a clinical decision-support tool costs around a million euros. No national funding body in Europe would finance that on its own."