LivingClimate change may bring new allergies

Climate change may bring new allergies

We are changing the climate , and this change affects many processes and events, both in the atmosphere and in living beings. A change in the environment can cause changes in the life cycle of the plants and animals that inhabit that environment, and even force their populations to move.

And since everything on the planet is somehow connected, these events can affect our health. For example, with pollen allergies.

Altering the rhythms of plants

It is a fact that the environmental modifications produced by global climate change cause changes in the behavior of plants . The increase in temperatures and a higher content of atmospheric carbon dioxide stimulates flowering , which is earlier than its natural cycle.

In some areas, birch pollen , for example, has advanced an average of 3 weeks in the last 20 years . In the same period, pines and grasses have advanced their pollination up to 15 days .
In addition, the flowering periods are getting longer.

And this has a direct effect: by advancing and extending the flowering periods, the period in which the pollen is released into the air is advanced. As a consequence, those allergic to certain pollen grains will suffer from spring allergies earlier and longer .

More and more pollen

Temperature variations also have a direct influence on pollen production. If less water availability is added to this, the plants will tend to produce more flowers to guarantee their offspring. Greater number of flowers per plant, and greater amount of pollen per flower , implies a significant increase in the amount of atmospheric pollen.

In Spain it is estimated that there was an increase of almost 150% in the annual content of pollen in suspension in the air between 1983 and 2008 . In some species, such as the cypress , this increase is quantified up to 229% .

They are also much higher in olive trees (195%) and in grasses (174%). All of them plants that produce allergenic pollen.

A higher concentration of pollen in the air not only harms allergic people , it also facilitates the sensitization of those who are not, favoring the appearance of new allergies .

New pollen from elsewhere

On the other hand, climate change also alters the distribution of plants . In general, global climatic changes have produced and will produce events of migration, extinction and redispersion of species and reorganization of the ecological structure.

As the climate changes, populations tend to move to where the climate is optimal for them, leaving the places where they once lived.

This destructures complex ecosystems and negatively affects ecological succession processes. When the climate changes drastically, the trees in a forest perish and the plant population moves elsewhere. It can be a long time until the vegetation dominates the new area again, and the land where the forest has disappeared becomes dominated by herbaceous plants and shrubs.

All this has several effects. On the one hand, the allergenic pollen reaches new territories where it was not previously, which can cause the sensitization of a part of the population, which has never had contact with these pollen grains. In addition, in general, herbaceous plants, including grasses, have higher pollen production and are more allergenic .

The parallel effect of pollutants

Although pollutants are not a consequence, but rather a cause of climate change, they also play a role in pollen allergies . It has been observed that the presence of pollutants can modulate the expression of certain proteins present in the pollen grain, which are ultimately responsible for the allergic reaction. This overexpression directly increases the allergenicity of the pollen, causing allergic people to suffer worse reactions, and facilitating sensitization by those who are not.

Given all these facts, it is important to maintain historical series of flowering and pollen shedding periods and active monitoring of plant populations with allergenic pollen, in order to be able to predict future trends and implement measures that can prevent epidemic episodes. of allergies . It is also essential to pay attention to the floristic composition of our parks and gardens , and avoid introducing species that could pose a risk to public health.

Most of the events of an epidemiological type tend to subside or attenuate; however, with pollen allergies, due to climate change and associated impacts, the opposite is true. It is a public health problem that is becoming more and more dangerous . Hence the need to seriously reflect on our great capacity to modify the nature that surrounds us, and the possible negative effects that these modifications can cause even on ourselves.


 Bortenschlager, S. et al. 2005. Altering airborne pollen concentrations due to the Global Warming. A comparative analysis of airborne pollen records from Innsbruck and Obergurgl (Austria) for the period 1980–2001. Grana, 44(3), DOI: 10.1080/00173130410005582

Cortegano, I. et al. 2004. Cloning and expression of a major allergen from Cupressus arizonica pollen, Cup a 3, a PR-5 protein expressed under polluted environment. Allergies , 59 (5), 485-490. DOI: 10.1046/j.1398-9995.2003.00363.x
Teran, LM et al. 2009. Allergy, pollens and the environment. Medical Gazette of Mexico , 145 (3), 8.
Teranishi, H. et al. 2000. Possible role of climate change in the pollen scatter of Climate Research, 14 (1), 65-70.
Valladares, F. 2009. Mediterranean forest ecology in a changing world . Autonomous Body National Parks.

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