As the planet warms, the far-reaching impacts of climate change on global health are becoming increasingly apparent. Rising temperatures, extreme weather events, and higher concentrations of air pollution are just some of the ways that changes to the climate can directly affect human well-being. Among the most troubling of these changes is the surge in airborne allergens, which are intensifying and spreading across the globe.
Fossil-Fueled Climate Change
The single largest source of greenhouse gases globally is oil and gas development, accounting for 74% of emissions that contribute to global climate change. The fossil fuel industry emitted 93% of CO2 emissions in the U.S. in 2022.
Greenhouse gas emissions from shale gas operations, which include hydraulic fracturing or fracking, are primarily composed of methane, a gas 80 times more potent that CO2. Despite industry claims that fracked gas burns cleanly, shale gas development and use produces CO2 in large quantities. One study predicts that a single shale gas formation in the U.S. could emit 27.8 billion metric tons of carbon over the lifetime of planned operations. At the moment, U.S. energy policy calls for an expansion of shale gas drilling. One of the most detrimental impacts of expanded shale gas production is that it could lead to a slower rollout of the transition to more renewable energy, which is crucial to curbing the climate crisis.
The knock-on effects of climate change are vast due to the intertwined nature of the climate with almost all natural processes. While higher temperatures, extreme weather conditions, lethal storms, and devastating wildfires are the most visible of these outcomes, many other processes are changing as global temperatures rise. One of these less visible outcomes is the increase in allergens and allergic responses in humans.
Allergens on the Rise
Pollen is a major allergen. It is estimated that 60 million people in the U.S. report having some allergic response to pollen. The addition of excess carbon dioxide (CO2) to the environment via climate change risks increasing pollen production across the board. This is because plants will take advantage of the excess CO2 in the atmosphere, increasing their biomass, photosynthesis rate, and efficiency with which they utilize water. This increased production will allow pollen-producing plants to get bigger, survive longer, and ultimately produce larger quantities of pollen.
In the United States, pollen seasons are beginning earlier and lasting longer, resulting in more individuals seeking seasonal allergy treatment. In 2021, the Centers for Disease Control and Prevention (CDC) reported that 1 in 4 adults and 1 in 5 children, totaling over 80 million, reported suffering from seasonal allergies. Depending on the type of pollen and when it spikes, emergency room visits can increase up to 20% during critical pollen episodes. And a recent study using advanced computer modeling to predict the effects of climate change on allergens found that found that, pollen loads will drastically increase, even in areas where such pollens are historically uncommon.
Changes in weather patterns also run the risk of increased mold growth in areas where they may not have grown before. Warmer temperatures and wetter storms are leading to longer periods of mold growth and spore production, particularly in temperate regions where these pollutants were not previously present. Increased flood risk is a particular danger, since disaster management may be stretched more thinly as disasters become more frequent and severe. Researchers predict that climate change will make weather conditions more extreme—areas that are already humid may become much more humid, increasing the risk of mold growth in these areas.
Allergen Health Effects on the Body and Beyond
The health consequences of this shift are significant, affecting millions globally who already suffer from allergic responses such as hay fever and eczema. However, the impact is far more serious than just discomfort. Increased exposure to allergens, especially among those with pre-existing respiratory conditions like asthma, can result in severe complications, including life-threatening asthma attacks. A 2023 EPA report indicated that annual cases of asthma are expected to increase between 4% and 11% as the planet warms between 2°C and 4°C.
Additionally, mold growth, exacerbated by warmer and wetter climates, poses significant health risks. Some molds produce toxic compounds called mycotoxins, which can cause severe reactions in vulnerable individuals. Long-term exposure to mycotoxins can cause immunodeficiency disorders and cancer in rare cases. In extreme cases, exposure to these molds can lead to life-threatening conditions like allergic bronchopulmonary aspergillosis or hypersensitivity pneumonitis. Studies have shown that mold exposure is linked to an increase in hospitalizations for respiratory issues and can trigger deadly fungal infections in people with compromised immune systems.
Chronic allergies can also take a toll on mental health if not properly managed or cared for. Studies have shown a link between severe allergic responses and increased anxiety, depression, and poor sleep outcomes. The stress of managing recurring health issues, coupled with the economic and social burdens, has a broader impact on individuals’ overall well-being.
The rising allergen load also has substantial economic consequences. Allergies are one of the leading causes of missed work and school days in the United States, with an estimated 4 million workdays lost annually due to hay fever alone. Americans spend upwards of $18 billion each year on allergy relief medications, medical visits, and other treatments. For those managing chronic conditions like asthma, the financial burden can be even higher, with regular hospital visits and medications driving up healthcare expenses.
Vulnerabilities
Children are particularly vulnerable to a world with more allergens. Due to the immaturity of their immune systems, allergy responses in children are either insufficient to suppress a wider infection, or their bodies are not strong enough to withstand the increased immune response.
Urban populations are also more vulnerable to an increased allergen content in the air. Those already exposed to ambient air pollution, as well as indoor air pollution due to poor housing conditions, may lead to increased asthma outcomes as a result of allergen exposure.
Interestingly, studies suggest that children in poor urban environments are less prone to food allergies, which may suggest a certain protective element against certain allergies due to high exposures at a younger age.
Finally, racial and ethnic minorities, especially African Americans and Hispanics, face higher rates of allergic diseases like asthma and food allergies due to environmental stressors, genetics, and limited access to healthcare.
What Can Be Done to Safeguard Health?
Various personal preventive measures may help lessen the exposure to allergens or reduce the impacts of health effects experienced.
Allergen avoidance: Staying indoors during peak pollen hours (mid-morning and late afternoon).
Air quality monitoring: Using resources like the National Allergy Bureau’s Pollen Count or Pollen.com to avoid allergen exposure.
Home interventions: Using air purifiers, keeping windows closed, showering after being outdoors to reduce exposure to pollen and mold.
Medication management: Preemptively using allergy medications like antihistamines, nasal sprays, and asthma inhalers as directed by health professionals.
The growing threat of allergens caused by fossil fuel-driven climate change poses serious health challenges, especially for vulnerable populations like children, urban residents, and racial minorities. As pollen counts rise and mold growth becomes more widespread, the number of individuals affected by respiratory issues such as asthma and allergic reactions is expected to increase. While personal preventive measures can help mitigate exposure, broader climate action and healthcare access improvements are necessary to safeguard public health in the face of this escalating risk.
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