The Overlooked Global Warming Cost We Can’t Ignore

Beyond being an environmental issue, climate change is a serious threat to public health, especially for individuals with food and respiratory allergies. A recent review in Laryngoscope found that climate change is altering pollen seasons and concentrations, allergic rhinitis (AR) disease prevalence, allergy sensitization, and AR symptom severity. Projections suggest that pollen emissions could rise by 16–40% by the end of the century, with pollen seasons lengthening by up to 19 days. These changes in the duration and intensity of allergy seasons could lead to increased frequency and intensity of allergy patients’ symptoms – particularly in sensitized individuals. 

Climate change not only impacts patients with respiratory allergies, but it also has potential broad and emerging impacts on patients with food allergies and overall public health. In the face of longer and more intense pollen seasons, rising temperatures, and increased pollution, it’s crucial for patients to determine the root cause of their allergy symptoms so they can work with their healthcare team to create an effective treatment plan. 

Climate change and respiratory allergies

As allergy seasons come earlier and last longer due to warming temperatures, it’s causing pollen seasons for trees, grass, and weeds to overlap, increasing pollen exposures. In addition to pollen seasons, weather in general can affect allergies. One phenomenon, thunderstorm asthma, happens when storms pulverize pollen due to dramatic environmental changes. When this happens, pollen is broken down into smaller particles, which, when inhaled, go deeper into the airways and cause more severe exacerbations of people with allergic asthma that are allergic to these pollens. Increased rain and humidity lead to the proliferation of common indoor allergens like mold and dust mites. 

Rising CO2 levels also affect mold and plant growth. With some species of mold, they grow three times the number of spores and produce twice the number of antigenic proteins that cause an allergic reaction or sensitization. Increased CO2 levels can also boost plant growth and pollen production, especially in weeds and certain grasses like Bermuda and Johnson grass, causing them to spread more and grow into regions that they wouldn’t normally grow into. For food allergies, elevated CO2 levels may also increase allergenic proteins in foods, such as the Ara h1 in peanuts, potentially making them more allergenic.

Beyond CO2, air pollutants like ozone, nitrogen dioxide, and particulate matter contribute to increases in allergies by damaging the epithelial barrier, whether it’s within the gut, respiratory tract, or even the skin. When this barrier is disrupted by these pollutants, it increases a patient’s exposure to allergens and sensitization, which can in turn lead to a clinical allergy. One study of children in China found that early-life exposure to high levels of outdoor and indoor air pollution leads to the first and second wave allergy epidemics, with the airway being a new route of food sensitization in addition to gut and skin. 

Beyond respiratory: Global warming’s implications for food allergies

In addition to the epithelial barrier dysfunction, there are other ways that people become sensitized through skin that are being impacted by climate change, like alpha-Gal syndrome (AGS), a type of serious, potentially life-threatening allergic reaction to red meat and other products made from mammals. A study by scientists at the University of Kansas, Kansas State University and Walter Reed suggests that in recent years, the lone star tick, which is known to cause AGS, has been found in increasingly northern and western locations, as far west as Wyoming and as far north as Maine, with researchers believing that the growth of the lone star tick’s habitat could be due to longer seasons of warm temperature caused by climate change.

The spread of mycotoxigenic fungi like deoxynivalenol (DON) is also suspected to be influenced by climate change, specifically linked to increased levels of CO2. Research found that these fungi can impair gut barrier integrity. In the research, mice that were fed barley, wheat, and corn contaminated by DON developed sensitization and a clinical allergy to peanuts. Offspring of exposed mice also showed increased susceptibility to egg allergies, suggesting possible generational impacts.

Pollution may influence not just prevalence of food allergies and related conditions, but also their severity. One Utah study found that higher levels of particulate matter among patients with eosinophilic esophagitis (EoE), who typically have worse symptoms during peak pollen seasons, were associated with an increased risk of symptoms due to impaction, where food becomes lodged in the esophagus.

The toll of allergies on healthcare system and how diagnostics can help

Each year, there are about 1.1 million emergency room visits associated with allergy-related conditions, with food allergy-related visits in the U.S. alone sending someone to the emergency room every 10 seconds. Emergency department visits for food allergies are a particularly significant cost driver, with one study estimating the overall cost of childhood food allergy in the United States at $24.8 billion annually, primarily due to inpatient, outpatient, and ED visits. If patients have an accurate picture of the triggers that cause their symptoms and take steps to avoid them, it can keep them out of the emergency department and hospital. To help alleviate this economic burden, the healthcare system must adapt as environmental changes continue to reshape pollen patterns and shift allergen exposure. 

As the environment continues to change and drive exposure to new allergens and increase existing sensitizations, prioritizing early and accurate allergy diagnosis can help patients avoid unnecessary exposure to allergens and proactively address their symptoms, reducing the severity of their allergic reactions and contributing to less unnecessary emergency department visits. Taking the right diagnostic approach ultimately shifts allergy management from proactive to reactive, ensuring better care and improved quality of life for patients.

Photo credit: BigStock Photo

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