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Human Health

From air quality to spreading disease, climate change is detrimental to human health. It creates conditions that are favorable to the spread of disease and makes it easier for respiratory issues to take hold. Even more relatable, climate change will expand pollen allergy seasons, affecting millions of people across the world. All of these effects also compound to affecting low-income and marginalized people the most since they don't have the same access to healthcare and treatment.

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Hana Prokop

Air Quality

Air quality has a tremendous impact on human health, as we all need clean, breathable air to survive. Unfortunately, climate change, greenhouse gas emissions, and more frequent wildfires cause air quality to deteriorate rapidly, increasing the risk of health complications and the development of respiratory and cardiovascular issues. Outdoor air pollution is staggeringly high, with 99% of the world’s population living in a place that did not meet the World Health Organization’s (WHO) Air Quality Guidelines in 2019. Unfortunately, air pollution has been steadily rising, increasing the risk of lung and other cancers in humans. Particulate Matter (PM) is used to represent air pollution, and particles with a diameter of fewer than 2.5 microns (represented as PM≤2.5) can actually enter the bloodstream by passing through the lung membrane. Any exposure to this particulate matter has negative health effects on humans, but increased long-term exposure to these small particles is directly linked to increased mortality.


Wildfires have been increasing in frequency due to climate change and droughts drying out organic matter which makes forests more likely to catch fire and increases the likelihood of those fires spreading quickly and uncontrollably. Wildfires release large quantities of carbon dioxide and harmful air particles, as discussed in the Air Quality section. In addition, wildfires have been shown to release massive amounts of mercury into the air by stirring up industrially sourced mercury that has settled in the soil. An estimated 44 metric tons of mercury are released into the atmosphere from United States wildfires annually, which can lead to decreased visual capabilities, difficulty walking, speaking, hearing, and more. 

Respiratory Concerns

While more research is needed to determine a direct link between climate change and respiratory diseases, the warming atmosphere causes an increase in ground-level (troposphere) ozone, a reactive gas that exists in the air we breathe. Breathing higher concentrations of ozone can result in decreased lung functions, asthma, airway inflammation, and other respiratory problems. The upward trend in both heat and ozone will put much more strain on individuals with respiratory conditions and can have lasting effects as humans are consistently exposed to both. Furthermore, as tropospheric ozone increases, stratospheric ozone decreases, removing much of the natural barrier from harmful UV rays that cause skin cancer and other diseases. Youth are especially at risk due to the fact that asthma is more common in children and ozone exposure is more prevalent outdoors. If significant mitigation efforts aren’t taken, growing up will be much more difficult for future generations. 

Allergies and Pollen

Pollen allergies are increasingly common in industrialized countries, and chances are we all know someone who has seasonal allergies. Changes in the climate drastically affect the production and distribution of pollen which can significantly aggravate those with preexisting allergies or respiratory conditions. Earlier spring seasons may kickstart allergy season faster, and rising carbon dioxide levels in the atmosphere can actually cause plants to undergo photosynthesis and the reproduction process more often. This process results in plants producing more pollen and further affecting those with allergies in addition to increasing the risk of developing allergies in those without current symptoms. Many studies have identified a link between high pollen counts, respiratory medication sales, and asthma-related hospital visits, demonstrating how a drastic increase in pollen could prove detrimental to the respiratory health of individuals all over the world. Rising carbon dioxide levels also affect the rate at which mold grows and spreads, which can be dangerous due to the fact that mold spores can reach into the respiratory tract (nose and lungs) to cause allergies or hay fever symptoms. Rates of pollen-adjacent respiratory issues such as asthma have increased, and seem to be continuing to rise just as temperatures and increased carbon emissions have. A recent study published in the National Academy of Sciences followed pollen levels from 1990 to 2018 and reported a 20.9% and 21.5% increase in annual and spring pollen concentrations, showing a sharp escalation in the intensity of allergy seasons worldwide. Allergists overwhelmingly predict persisting allergies even past the typical spring allergy season, and the specialists predicted the need for “increased care for allergic sensitization and symptoms of exposure to plants or mold.”

Diseases and Pests

Climate change impacts the incidence of vector-borne diseases such as Lyme disease, West Nile Virus disease, and more. While many Vectorborne and Zoonotic (VBZD) diseases are prevalent mainly in developing countries, climate migration, due to rising temperatures and natural disasters, threatens to spread these illnesses further. Significantly, vectors (carriers of disease) such as mosquitos and ticks are able to thrive in warmer climates. As the world turns towards longer, hotter summers and potentially shorter winters, these vectors have the opportunity to reproduce and survive in a wider geographic and seasonal area. For instance, an increase in the spread of Lyme disease is predicted as the ticks that carry it are able to live longer and spread farther north. This scenario is likely the case for many other diseases, causing many risks for increased pest transmission in the United States. In addition, warmer temepratures may lower the time it takes for disease to take hold of someone's body (the incubtaion period), which could disastrously increase the disease spread. Climate change is allowing these diseases to affect new populations, resulting in the threat of these diseases rising even in areas like the United States where they have not been found in some time.


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