Allergies, asthma, and climate change

Rising global temperatures are damaging not only our ecosystem, but also our health, for example by affecting food supplies and exacerbating disease.1 Many studies have examined correlations between climate change and disease, from cardiovascular disease to respiratory diseases. . For allergies and asthma, data is emerging on the potential impacts of climate change, such as contributing to the onset of allergic disease and asthma and creating conditions that exacerbate pre-existing allergies and asthma.1

Allergic rhinitis/hay fever


Common aeroallergens in the environment are pollen (tree, grass, weeds), dust mites, mold, pet dander and mice. Environmental allergies are on the rise and it is estimated that up to 40% of children have symptoms of allergic rhinitis.2 In 2018, there were 12 million visits in the United States where allergic rhinitis was listed as the primary diagnosis.3 The increase in the incidence of allergic rhinitis, usually hay fever is likely multifactorial, with climate change playing a critical role due to rising temperatures and rising carbon dioxide levels. Due to global warming and climate change, pollen seasons are longer and more pollen is produced. Drastic changes in temperature can potentially make pollen more potent.1 It takes a few seasons of exposure for pediatric patients to develop allergic rhinitis, and the risk of developing allergic rhinitis increases with age. A study in Europe, modeling the effects of climate change, estimated that the number of patients with ragweed allergies would double in some regions in the coming decades.4 However, the effects of climate change and allergies are not limited to pollen.


Rising temperatures with increasing humidity also create an ideal breeding ground for mold.1 These conditions can contribute to increased mold growth outdoors, which can have adverse health effects, especially for patients with asthma. In a Chicago study, death rates from asthma were twice as high when the amount of Alternaria outdoors was high


allergic asthma

The majority of asthmatics are allergic in pediatric patients. Multiple factors that contribute to climate change and its effects on environmental allergens (eg pollen and mold) can contribute to the development of asthma or worsening of symptoms. Some studies have shown that the effects of climate change result in pollen with a stronger binding of immunoglobulin E, such as birch pollen, which may contribute to pollen-induced asthma exacerbations.1

Along with global warming and climate change, some regions are experiencing increased precipitation and flooding that can contribute to the spread of fungi. Moisture has been linked to the spread of mold, which is known to contribute to the development of asthma and worsening asthma symptoms.5 In the aftermath of Hurricane Katrina, clinical trials showed that flooded homes showed more mold , and implementing environmental remediation can help mitigate adverse respiratory effects

thunderstorm asthma

After thunderstorms, asthma attacks and visits to asthma-related emergency rooms (ED) are reported to rise, a phenomenon called “thunderstorm asthma.” It has been postulated that asthma during thunderstorms is primarily caused by grass pollen, but some weed pollen and fungi may also play a role. Larger particles of pollen and molds are broken down into smaller particles that increase the concentration in the air. During thunderstorms, high winds allow the smaller particles to travel farther, and they can also travel deeper into the lungs and cause asthma flare-ups or respiratory symptoms.1


With the increase in carbon emissions and other pollutants, these gases become trapped in the atmosphere and reduce air quality. Major pollutants, including nitrogen dioxide (NO2), ozone, diesel fuel exhaust and particulate matter, are known to aggravate asthma. In addition, pollutants increase airway permeability and may enhance the effects of pollen in sensitive individuals.6

forest fires

The increasing number of wildfires can also contribute to the development of respiratory diseases, including asthma. This is especially important in pediatric populations because of the small surface area of ​​their lungs. Just a small amount of exposure to air pollution from wildfires can have dangerous effects on respiratory health. In a recent California study, wildfire particulate matter was 10 times worse compared to environmental particulate matter exposure, resulting in increased emergency and emergency care visits for respiratory symptoms, including asthma attacks, coughing, and wheezing in children.7 In addition, recent findings published in JAMA linked wildfires with higher health care use for atopic dermatitis flares, and patients reported worsening itching8

Health inequalities and vulnerable populations

In the United States, there are striking health disparities between multiple health conditions. Colored and low-income communities suffer disproportionately from the prevalence, morbidity and mortality in many disease states. The effects of global warming and climate change are likely to widen health disparities. For example, black and Puerto Rican people have twice the asthma prevalence of white people, as well as higher asthma morbidity. Air pollution is known to aggravate asthma, and there is higher exposure to environmental air pollution in communities of color. In a study conducted in California, despite fuel-efficient cars, traffic-related NO2 levels were higher in communities of color and low-income neighborhoods. Levels were 37% higher in non-white communities.9 Living conditions and the built environment play a critical role because, although climate change is a global phenomenon, vulnerable populations are disproportionately affected. For example, in communities of color, schools may be closer to roads, which multiple research findings show contribute to asthma morbidity. Prenatal exposure, early exposure and exposure to pollutants in childhood may have a synergistic effect on respiratory health

How to help

Practicing clinicians play a critical role in helping to combat the adverse health effects of climate change, starting with evaluating and treating patients. This goes beyond individual patient care and includes advocating for policies to reduce carbon emissions and greenhouse gases, with an emphasis on protecting vulnerable populations who experience the impacts disproportionately and are at greater risk. At the individual patient level, it is important to take a detailed clinical history, including environmental history to assess exposure and refer patients to appropriate resources, such as social workers or case managers (Table 1). Clinicians should also empower patients by providing them with strategies to reduce environmental exposure (Table 2). It is also important to work with both local and national medical associations to drive policy changes at all levels. For example, the American Academy of Pediatrics has a Climate Change Initiative that brings members and partners together to educate and advocate for policy changes to combat the risks of climate change to human health. The doctor’s voice must be heard to ensure that patients’ health needs are at the heart of the fight against climate change.


1. Poole JA, Barnes CS, Demain JG, et al. Impact of weather and climate change on indoor and outdoor air quality in asthma: a working group report of the AAAAI Environmental Exposure and Respiratory Health Committee. J Allergy Clin Immunol. 2019;143(5):1702-1710. doi:10.1016/j.jaci.2019.02.018

2. In-depth assessment of allergic rhinitis. World Allergy Organization. Accessed May 24, 2021. %20people%20suffer,fifth%20most%20normal%20chronic%20disease

3. Allergies and Hay Fever. Center for Disease Control and Prevention. Accessed May 25, 2021.

4. Lake IR, Jones NR, Agnew M, et al. Climate change and future pollen allergy in Europe. Environment Health perspective. 2017;125(3):385-391. doi: 10.1289/EHP173

5. Baxi SN, Portnoy JM, Larenas-Linnemann D, Phipatanakul W; Working group Environmental allergens. Exposure and health effects of fungi on humans. J Allergy Clin Immunol Pract. 2016;4(3):396-404. doi:10.1016/j.jaip.2016.01.008

6. D’Amato G, Chong-Neto HJ, Monge Ortega OP, et al. The effects of climate change on respiratory allergy and asthma caused by pollen and mold allergens. Allergy. 2020;75(9):2219-2228. doi:10.1111/all.14476

7. Aguilera R, Corringham T, Gershunov A, Leibel S, Benmarhnia T. Fine particles in wildfire smoke and pediatric respiratory health in California. Pediatrics. 2021;147(4):e2020027128. doi:10.1542/peds.2020-027128

8. Fadadu RP, Grimes B, Jewell NP, et al. Association of forest fire air pollution and health care use for atopic dermatitis and pruritus. JAMA-dermatol. Published online April 21, 2021. doi:10.1001/jamadermatol.2021.0179

9. Nardone A, Neophytou AM, Balmes J, Thakur N. Ambient air pollution and asthma-related outcomes in children of color in the US: a scoping review of literature published between 2013 and 2017. Curr Allergy Asthma Rep. 2018;18(5):29. doi:10.1007/s11882-018-0782-x

Comments are closed.