The Impact of Climate Change on Allergies
Climate change is hurting the earth and your health
From rising temperatures and sea levels, melting of the ice caps, and increases in extreme weather events, we all hear about how climate change greatly impacts the environment. But climate change is also a threat to your health. It is leading to increased allergens in the air causing worse symptoms of seasonal allergies and asthma.
What is climate change?
Scientists predict that 95% of climate change related events are caused by human activity and the burning of fossil fuels. Fossil fuels are mostly burned for transportation and industrial use, including cars, ships, airplanes, and coal-fired power plants. The burning of fossil fuels releases harmful gasses into the atmosphere. These gases, called greenhouse gases, include carbon dioxide, methane, nitrous oxide, and water vapor. Greenhouse gases get trapped in the atmosphere and cause changes in the climate.
Carbon dioxide is one of the greatest driving factors of climate change. It can stay in the atmosphere for 300-1,000 years, impacting many generations to come. Scientists predict that atmospheric carbon dioxide levels have increased 47% since the industrial revolution. Carbon dioxide has not only been shown to lead to rising temperatures, but also increased crop plant growth. Plants need carbon dioxide to survive, and with the abundance in the atmosphere, they are able to grow faster and larger, resulting in increased pollen production.
Fall allergies
One of the plants benefiting from increased carbon dioxide levels is ragweed. Ragweed blooms during late summer and fall and is the underlying allergen responsible for 75% of the cases of hay fever in the US. Symptoms of hay fever, or allergic rhinitis, include eye irritation, runny nose, sneezing and congestion.
Not only does ragweed produce more pollen when atmospheric carbon dioxide rises, the pollen it releases is more potent. One study found a correlation between increased levels of carbon dioxide and allergenic protein in ragweed pollen. In a controlled experiment, the concentration of atmospheric carbon dioxide was adjusted to replicate pre-industrial conditions (end of the 19th century), current conditions, and predicted conditions (middle of the 21st century). The amount of allergenic protein in ragweed pollen increased by 70% when carbon dioxide levels were raised above the current conditions. As carbon dioxide levels rise, the allergenicity of ragweed pollen is expected to increase and subsequently the prevalence and severity of hay fever symptoms will too.
Spring allergies
Trees typically release their pollen in the early spring while grasses pollinate later on, triggering allergy symptoms for many throughout the months of March- June. The rise in temperatures has caused an increase in the duration of the pollen season. From 1995-2011, pollen seasons in the US became 11-27 days longer. Causing people with allergies to trees, grasses and weeds to suffer with symptoms for longer.
Warmer temperatures also favor the expansion of the habitats suitable for more allergenic tree species. Oak and hickory are two highly allergenic tree species that thrive in warmer climates. The increased temperatures have favored their growth in the Northeast region, from Pennsylvania to Maine. On the other hand, the warmer climate is harmful to species like pine, spruce and fir which are less allergenic trees.
Indoor allergies
The change in climate is also impacting molds and other fungi, which can cause allergy symptoms year round. Molds can grow outdoors on rotting logs, fallen leaves, and in compost piles. They can also grow indoors in damp areas, like bathrooms, kitchens and basements.
Extreme weather conditions, like heavy rainfall and flooding have increased with the changing climate. These events lead to an abundance of fungal spores and molds which thrive in dampness. The worsening of allergy symptoms, chronic coughs and childhood asthma reported in New Orleans after Hurricane Katrina is just one example of how extreme weather can increase the prevalence of allergies.
Asthma
Some patients with environmental allergies also suffer from asthma. More than 25 million people in the US have asthma, and allergic asthma accounts for 60% of those cases. Greenhouse gases interact with allergens in a way that amplifies both of their harmful effects on the lungs.
Ozone, a toxic gas, is formed at ground level when air pollutants emitted by cars, power plants, industrial boilers, chemical plants, and other sources react chemically in the presence of sunlight. The increased use of fossil fuels have caused ozone levels in the lower atmosphere to rise. Ozone primes our lungs to be more sensitive to allergens, making less pollen necessary to trigger an asthmatic response.
When air pollution like diesel exhaust particles are inhaled, they can stay in our lungs for a prolonged period of time. Airborne pollen grains can attach to the harmful air pollutants and penetrate the lungs, staying in our bodies for a longer period of time. The prolonged exposure increases the duration and severity of asthmatic symptoms.
Similar to rising carbon dioxide levels, air pollution has also been shown to increase the amount of allergenic proteins in some plant pollen. Making allergic asthmatic symptoms more prevalent and severe.
What can you do to protect yourself from the harmful effects of climate change?
Speak to your doctor about how to avoid places and situations that may cause allergic reactions or asthma attacks.
Check the Air Quality Index to see how polluted the air is before leaving your home. On days the pollution is high, try to avoid outdoor activities.
Get allergy testing so you know what plants can trigger your allergies and when they bloom so you can reduce time spent outside when necessary.
Speak to your medical provider about air pollution and allergens, and how to minimize exposure.
Advocate for your health and support policy makers who are working to reduce climate change.