[INFORMATIVE] Worsening Allergies in a Warming World: How climate change is altering our immune responses

Worsening Allergies in a Warming World: How climate change is altering our immune responses

By: Leah Mari Li

As the world is facing the growing impacts of climate change, from endangered polar bears to suffering rainforests and melting ice caps, we, too, are slowly feeling the alarming heat in increasingly obvious ways. In addition to these problems, we are breathing in the literal effects of global warming. Pollen is becoming more and more of a pest, plague, and a pandemic. In the UK alone, approximately 44% of all adults are suffering from at least one allergy. For millions of people, the sneezing, coughing, and itching eyes of the allergy season are becoming a familiar battle, and they are all linked to the warming of the globe.

Allergies 101
Allergies are caused by both genes and environmental factors. They occur when the immune system mistakens a harmless substance, such as pollen, as harmful and tries to attack it. The primary function of the immune system is to protect the body from potentially harmful invaders, such as bacteria, viruses, and toxins. By detecting the unique proteins on the surface of these invaders, it recognizes the threats. The immune system consists of two components: innate immunity, which acts as a general defense mechanism, and acquired immunity, which develops when individuals are exposed to pathogens. Additionally, passive immunity is passed from the mother to the child through breastfeeding or the placenta.

Difficulties arise when the immune response is either underactive or overactive. When the immune system mistakenly identifies a harmless substance as a pathogen, it triggers an immune response. This might include inflammation, sneezing, itching, and even nausea. Pollen especially affects the immune system, with 1 in 5 people experiencing hay fever at some point in their lives.

Rising heat, rising risks
There are several ways in which climate change impacts our allergies. With rising temperatures, we notice a significant shift in our seasons, as spring arrives earlier and autumn arrives later. Comparing the start of the pollen seasons, biology professor William Anderegg‘s research shows that the allergy season starts approximately 20 days earlier today than in the 1990s.

Warmer temperatures can either encourage or restrain vegetation growth, thereby impacting annual pollen production. However, not only are the seasons longer, pollen production itself is also intensifying. Increased CO2 levels in the atmosphere may support photosynthesis that facilitate pollen production. Similarly, a high CO2 concentration may lead to a higher number of male flowers and therefore a higher number of allergens.

While you might think that this is primarily bad news for people who are already allergic, these changes could harm anyone. According to professor and allergy specialist Leonard Bielory, longer exposure increases the probability of being sensitized to that specific allergen. Thus, pollen allergies could intensify symptoms, and even people without allergies may start to develop them.

In particular, urban populations are affected by the change. Harmful pollutants like particulate matter (PMx), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO) directly alter the physical and chemical properties of pollen grains. This pollution is all caused by human activities like car emissions, industrial processes, power plants, and the burning of fossil fuels. However, it does not just make the air harder to breathe—it transforms the pollen itself. Pollutants can modify the surface of the pollen and alter the molecular structure of its protein, increasing its allergenic potential.

However, city dwellers also suffer from another issue.Many city planners prefer planting male trees to avoid fruit and seeds that produce pollen instead of fruit. Some experts have, however, disagreed with this statement, as most trees have both male and female reproductive parts.

Another reason for the increase in allergies could be social behavior. Bacteria and diverse microbiota are crucial for human health, yet with our modern, western lifestyle, our exposure to microorganisms is far more restricted than it was in the past. According to Finnish scientists, microorganisms found in natural environments play an essential role in maintaining the immune system.An analysis of the bacteria on the skin of teenagers in Finland found that those living near farms or forests had a higher diversity of bacteria and, in addition to that, exhibited lower allergen sensitivity. Similarly, urban lifestyle limits microbial exposure to newborns, which hinders early colonization of the infant gut. A previous study found that babies who have been exposed to both bacteria and allergens within the first year of life are less likely to develop asthma and allergies later on.

How to allergy-proof your life
Although it is impossible to control every factor that influences an individual’s allergies, there are small steps you can take to manage symptoms. Experts advise keeping windows closed during pollen seasons, using air purifiers, and regularly cleaning homes. Furthermore, you can also check the air quality index to determine how polluted the air is at that moment. If you must go outside, you should wear sunglasses, a hat, or even an FP2 mask to create a barrier between you and the allergen.

Citations
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Mayo Clinic. (2018). Allergies - Symptoms and Causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/allergies/symptoms-causes/syc-20351497‌

Allergy UK. (2022). Statistics and Figures. Allergy UK | National Charity. https://www.allergyuk.org/about-allergy/statistics-and-figures/

‌“Hay Fever.” NHS Inform, www.nhsinform.scot/illnesses-and-conditions/immune-system/hay-fever/#:~:text=Hay%20fever%20is%20a%20common.

‌Harrington, S. (2023, April 19). “In every breath we take”: How climate change impacts pollen allergies» Yale Climate Connections. Yale Climate Connections. https://yaleclimateconnections.org/2023/04/in-every-breath-we-take-how-climate-change-impacts-pollen-allergies/

‌Zhang, Yingxiao, and Allison L. Steiner. “Projected Climate-Driven Changes in Pollen Emission Season Length and Magnitude over the Continental United States.” Nature Communications, vol. 13, no. 1, 15 Mar. 2022, p. 1234, www.nature.com/articles/s41467-022-28764-0, https://doi.org/10.1038/s41467-022-28764-0.

‌Capone, P., Lancia, A., & D’Ovidio, M. C. (2023). Interaction between Air Pollutants and Pollen Grains: Effects on Public and Occupational Health. Atmosphere, 14(10), 1544. https://doi.org/10.3390/atmos14101544

‌Do seasonal allergies seem to be getting worse? Blame climate change. (n.d.). AAMC. https://www.aamc.org/news/do-seasonal-allergies-seem-be-getting-worse-blame-climate-change‌

Shute, Nancy. “Early Exposure to Bacteria Protects Children from Asthma and Allergies.” NPR, 6 June 2014, www.npr.org/sections/health-shots/2014/06/06/319420973/early-exposure-to-bacteria-protects-children-from-asthma-and-allergies.‌Kinver, Mark. “Lack of Contact with Nature ‘Increasing Allergies.’” BBC News, BBC News, 4 May 2012, www.bbc.com/news/science-environment-17952320. Accessed 14 Sept. 2024.