Tough spring expected for allergy sufferers

This year, people allergic to winter pollens (mainly cypress, ash, hazel and parietaria) began to experience symptoms in mid-February, at which time pollination took off with force, exceeding the normal concentrations recorded from 1994 to 2025.

Given that the year has started with cool temperatures, most winter flowering plants have not released pollen until mid-late February, somewhat later than in previous years, but with higher than normal concentrations thanks to the abundance of water. Pollen from shade trees will appear a little later than usual, starting pollination in mid-March when they usually do so at the beginning of the month. Therefore, allergy sufferers should take all appropriate precautions to minimise symptoms.

Weather models indicate that March will be slightly warmer and much rainier than normal. April, May and June are expected to have normal or slightly above normal temperatures, and April and May will see normal rainfall.

With this information, the forecast of pollen and spore levels in the atmosphere in Catalonia for the coming months made by the Aerobiological Network of Catalonia (XAC) of ICTA-UAB and the Department of Animal Biology, Plant Biology and Ecology of the UAB (BABVE), led by researcher Jordina Belmonte, is as follows:

• At the beginning of 2026, winter pollinations of cypress, hazel, ash and parietaria were lower than the historical averages recorded since 1994, but increased very suddenly in February and March, significantly exceeding the averages. The latest rains have eliminated pollen from the air, but the allergy risk period may extend well into April for cypress and into summer for parietaria, although the cold and rain will contribute to notable occasional drops in concentrations.
• Spring pollinations of tree species (plantain as very allergenic, but also willow, poplar, elm, maple, pine, mulberry, oak-holm oak and, later, birch, and olive tree) will begin normally and strongly, and will have the usual duration.
• Spring-summer pollinations of herbaceous species (parietaria and grasses as very allergenic and early, and later also wheat, plantain and mugwort) will begin normally and strongly, and will last longer than usual, benefiting from the rains forecast by the meteorological services.

These predictions could be modified if the following occurs:

• The episodes of rain are heavy and occur during daylight hours, because they will drag the pollen to the ground and can reduce the risk of allergies (this happens mainly with tree pollen). They will also reduce grass pollen, but this would be temporary, because the plants will be able to bloom again and extend the period of presence of pollen in the air.
• The temperatures are high (above normal), which would make it possible to reduce and shorten the pollination of plants (especially herbaceous plants).
• There are episodes of very strong winds. If this wind comes from directions without or with little pollen/spores (for example, from sea to land or from areas with little vegetation), it could reduce their concentrations and modify the composition of the spore-pollen spectrum. Conversely, wind coming from areas with a lot of pollen/spores could increase the risk of allergies.

According to the XAC, the most abundant types of allergenic pollen in general in the atmosphere of Catalonia are cupressaceae (22%), plane tree (10.7%), olive tree (5.0%), parietaria (4.4%), hazel (4.3%), grasses (4.2%), ash (2.8%), buckthorn (1.8%), and mugwort (0.5%), with significant variations in quantity depedning on the geographical and climatic zones of Catalonia. The spores of the alternaria fungus, despite their significance in allergies, are not among the most abundant in the air (1.9% of the total number of spores). The XAC emphasises that attention must also be paid to other taxa, sometimes not considered in the diagnosis, such as pine (16.3%), holm oaks and oaks (13.1%), birch (3.2%), plantain (2%), poplar (1.8%), alder (1%), honeysuckle (0.4%) and others that may have local impacts. The excellent collaboration existing in Catalonia between biologists-botanists and medical specialists helps with the precise diagnosis in each case.

The XAC has updated the study of trends in the total annual amount of nine main types of pollen and one fungal spore, measured in the nine study locations since 1994. The results reveal that:

• The locations where taxa is decreasing the most are Tarragona, Manresa and Bellaterra-UAB, followed by Girona, Barcelona and Vielha. The one with the greatest number of increasing taxa is Lleida, followed by Roquetes-Tortosa.
• The towns ranging from the highest number of decreases to the highest number of increases are: Tarragona, Bellaterra-UAB, Manresa, Girona, Planes de Son, Barcelona, ​​Vielha, Roquetes-Tortosa and Lleida.
• Tree pollens (cypress, banana, olive and ash) tend to increase.
• Hazelnut bush pollen only decreases significantly in Tarragona (possibly due to the abandonment of crops).
• Grass pollens (parietaria, grasses, brooms and mugwort) show mostly decreasing trends, especially mugwort, urticaceae (Parietaria), brooms and grasses. Grass and broom pollen are the ones that show the most increasing trends.
• The alternaria fungus shows increasing trends everywhere, except in Bellaterra-UAB and Roquetes-Tortosa.

Respiratory allergies and other related diseases

Dr Gaspar Dalmau, specialist in allergology at the Joan XXIII University Hospital in Tarragona and president of the Catalan Society of Allergology and Clinical Immunology (SCAIC), highlights the importance of bronchial asthma and allergic rhinitis in both children and adults. These chronic diseases of the respiratory tract complicate the health of the diagnosed allergic population, especially in spring, and can also affect those who present allergy-compatible symptoms for the first time. Early detection is essential to prevent the progression of rhinitis to asthma, as well as the development of other associated allergic diseases, such as atopic dermatitis or food allergies. This aspect is particularly relevant in the pediatric population, since early diagnosis and appropriate treatment can stop the well-known "atopic march", highlighting the role of allergology as a transversal speciality capable of having a global vision of the allergic patient, whether they have nasal, ocular or bronchial involvement.

Increase in the prevalence of respiratory allergies

Allergic diseases represent a public health concern in Catalonia due to their strong impact on the healthcare system and the quality of life of patients. The high demand for healthcare, which includes emergency room visits, hospitalisations and chronic treatments, is exacerbated when there is no adequate diagnosis and treatment. In the social and economic field, these diseases generate job losses and school absenteeism, also affecting caregivers of pediatric patients.

Respiratory allergy is the most common. In Catalonia, nearly two million people suffer from some type of respiratory allergy, and this figure is expected to double by 2050. According to estimates by the SCAIC, 25% of the population has rhinitis, with or without allergic conjunctivitis, and up to 12% suffer from allergic asthma. The average age of patients who consult for rhinoconjunctivitis and asthma is 30 and 29 years, respectively, with a predominance of females in both cases (55.4% in rhinoconjunctivitis and 55% in asthma).

The data show two peaks in the incidence of asthma: in children aged 5 to 15, and in adults aged 35 to 40. Furthermore, in four out of ten cases, asthma and rhinoconjunctivitis are caused by pollen, which represents the first cause of rhinoconjunctivitis and the second of asthma. Therefore, the quantification of pollen in the atmosphere is key to designing therapeutic and preventive strategies adapted to each patient.

Is pollen becoming increasingly allergenic?

The development and aggravation of allergic diseases depend on genetic and environmental factors. Climate change modifies the pollination patterns of many plants, extending the duration of their emission and increasing their concentration in the air. In Catalonia, current climatic conditions, with mild winters and increasingly warm summers, favour the proliferation of pollen-producing species.

The increase in temperature and carbon dioxide (CO2) levels enhance the production of pollen, prolonging the exposure season and increasing the presence of allergens in the air. In addition, air pollution not only damages the respiratory tract, but also alters the composition of pollen, making it more allergenic. These circumstances explain the continuous growth of allergic diseases, turning them into a public health challenge that requires preventive and therapeutic strategies adapted to the current environment.