The month of March brings the beginning start of the spring season. For some, this only means warmer weather and getting to see the spring flowers bloom. But it also marks the beginning of allergy season, where pollinating flowers and increasing temperatures trigger discomfort, affecting the quality of life for many. This period is exacerbated by the changing climate.

Climate change is a serious global issue, resulting in severe environmental and weather changes such as floods, drought, hurricanes and thunderstorms. They also have a significant effect on human health, particularly allergies.

Around 30-40% of the world’s population suffers from some type of allergy. Due to drastic climate changes, this has been predicted to only increase in the future and can be attested to the increased pollen counts and global temperatures.

Allergies can significantly affect the quality of life of individuals. This article will explore the specific effects of climate change on respiratory allergies, and what can be done to help.

How can climate change increase allergies?

An allergy is when an individual’s immune system has an adverse reaction to a substance, for example, a certain type of protein in food or pollen in the air.  Climate change affects the air quality, and can therefore have profound effects on human health and allergy.

Changes in the air

Climate change induces changes in temperature as well as increased carbon dioxide (CO₂) emissions due to fossil fuel emissions. Increases in CO₂ concentrations and their effects on the environment have been well-established. Concentrations of the greenhouse gas have increased from 280 parts per million (ppm) in 1870 to 421 ppm in 2022 and only continue to increase, inducing significant changes in the atmosphere.

There has been a drastic increase in the number of people suffering from respiratory allergies over the last 60 years and is expected to rise to 4 billion by the 2050s. One of the reasons for this includes the changes in duration and amount of pollen present in the air. This could be due to certain plants that thrive off CO₂ increasing in growth, and in turn, releasing more pollen by-products for longer periods.

Climate change, pollen and allergy

The link between respiratory allergy and climate change is well-defined. Pollen is a large cause of respiratory allergies, including asthma and rhinitis (or hay fever). Allergic rhinitis is caused by breathing in pollen, dust or other particles (all known as aeroallergens) that may induce an allergic response. This results in inflammation of the airways, resulting in symptoms such as sneezing, itchy nose and sinuses. More severe and long-term symptoms include coughing due to restriction of the airways, sore throat, headaches and irritability.

Allergic asthma is also triggered by breathing in aeroallergens and is the most common type of asthma, causing restriction of airways. Symptoms include shortness of breath, wheezing and coughing, and in severe cases can be fatal.

Studies from around the globe including Australia, USA, Spain and Canada have illustrated the clinical significance of increased pollen counts, with higher pollen counts resulting in more emergency hospital visits for asthma. Furthermore, due to climate change and rising temperatures, pollen seasons are lasting longer, affecting more individuals and therefore resulting in more hospital visits.

An increase in air pollutants such as ozone and nitric oxide has also been linked to climate change and may be related to the increase in allergic respiratory diseases. As polluted air is inhaled, toxic chemicals may cause irritation and inflammation to the airways. This inflammatory response makes the airways vulnerable to entry of further toxins and allergens such as pollen. Exposure to Ozone and nitric oxide in early life has been shown to increase the risk of asthma in children by up to 17%, and eczema by 7%.

Thunderstorms and allergy

Severe weather changes, such as thunderstorms can also trigger allergies in humans. Thunderstorms can result in sudden, large amounts of allergens being released into the air, which, when inhaled, can trigger severe allergic outbreaks.

This was seen in 2016, after a thunderstorm hit Melbourne, Australia.  A high level of pollen was released into the air during the thunderstorm, along with excessive rainfall. This rainfall resulted in breaking pollen grains open to release finer pollen particles that were breathed in and taken in by lower respiratory airways, resulting in a large allergic outbreak. The thunderstorm resulted in 10 deaths due to allergic asthma and 9000 subjects in hospital due to severe and near-fatal allergic asthma.

As we have seen, climate change has a significant effect on allergies in humans, making it a public health issue. Although climate change is a large-scale and complex issue that does not have an easy ‘fix’, there are steps that can be taken to mitigate the effects it has on human health, particularly on allergies.

Adapting to the changing climate

Adaptation and mitigation are key of dealing with the changing climate and increasing disease. An article in MDPI’s International Journal of Environmental Research and Public Health (IJERPH) reviews the key ways of adapting to climate change in regards to allergy.

One way involves monitoring the levels of aeroallergens and forecasting the level of aeroallergens in a given time or space. This could be key in reducing the number of hospital visits that are a direct result of elevated pollen counts in the air. By advising people who suffer from allergic asthma and rhinitis to stay at home during this time, it will reduce their overall exposure to aeroallergens, and hence reduce severe symptoms.

Furthermore, the review discusses frameworks should be put in place by governments and councils to ensure that plantation of green spaces are carefully planned out in terms of 1) type of plants used and 2) location of plants in populated areas. This means that planting low-level pollinating plants is important, resulting in a lower amount of allergens in the air over time. Educating communities to plant these types of plants in private gardens, rather than plants that release high concentrations of pollen for long periods, is also key in helping to reduce allergic disease burden.

Plants that depend on pollination by animals and insects are much more beneficial to plant in gardens compared to plants that are pollinated by wind. Some plants or flowers that have been deemed suitable for ‘low allergy gardens’ include Geraniums, Irises, Begonias and Nigellas.

Access to healthcare and future research

Ensuring that all individuals that suffer from allergies are readily equipped with the correct medication is of utmost importance to mitigate the effects of climate change. With the weather and environment becoming increasingly unstable, immediate access to life-saving medication is vital, along with access to appropriate health services that can quickly and efficiently cater to the needs of these individuals.

More research on the topic of climate change and how it affects the extent of allergies in humans is of great importance for public health and reducing disease burden. This includes more efficient monitoring on aeroallergens and epidemiological studies of their effect on the population. MDPI journals such as Atmosphere and IJEPRH publish the most up-to-date research, including themes on allergy and climate change that are accessible and free to read immediately. If you would like to contribute to this important field of research and publish your work on climate change or allergy, please click here for the full journal list.