Asthma and Allergy

Asthma and Allergy

Allergy and asthma are two of the most common chronic diseases in Europe, and they are often interlinked; Asthma occurs either due to an allergic (IgE-mediated) background, called allergic asthma, or on a non-allergic background, called intrinsic asthma.

Asthma causes inflammation of the smaller airways of the lungs, resulting in breathlessness and wheezing, with severity and frequency varying from person to person. At the moment of an asthma attack, the lining of the bronchial tubes swell, causing the airways to narrow thereby reducing the flow of air into and out of the lungs.

Allergies are immunological hypersensitivities that can lead to a variety of different diseases. Patients with allergies make IgE antibodies against environmental or dietary proteins. Besides allergic asthma, allergies manifest also in various forms such as anaphylaxis, allergic rhinitis, and atopic dermatitis. The most common allergen are pollen, pets, house dust mite, venom allergens, and food allergens. Several environmental risk factors including indoor and outdoor pollution, as well as climate change can elicit and/or exacerbate allergic diseases.

Both allergies and asthma can appear at any age, although very often start in childhood and teenage years. Given the impact and severity of these diseases, it is fundamental to better understand their causes and work towards prevention, particularly in childhood.


In Europe, more than 150 million people are affected by allergy and its prevalence is steadily rising. By 2050, it is estimated that half of the European population could be affected by allergies.

Meanwhile, 30 million children and young adults in Europe are asthmatic, a number that has steadily increased in the last 60 years in industrialised countries. It estimated that the 12.8% of six-year-old children are asthmatic, with a slightly higher prevalence in girls (13.2%) compared to boys (12.3%), and generally, with higher incidences in Northern and Western European countries. 60% of school-aged asthmatic children also have allergies, and between 6.5% and 24.6% of the children self-reported to have at least one food allergy in Europe.


While there are significant psychosocial and economic burdens for patients living with allergy and asthma, there are also additional indirect costs to the economy.

In the EU, insufficiently treated allergies lead to costs ranging between 55 billion and 151 billion euro per year. Appropriate treatments could lead to average savings of around 142 billion euros per year.

The total cost of asthma in Europe is 17.7 billion EUR per year, and productivity loss due to patients’ poor control of their asthma is estimated at 9.8 billion EUR per year. Up to 62.5% of the total costs caused by asthma are related to working days lost and days with limited, non-work-related activities. Additionally, asthma is the leading cause of school absences, emergency visits and hospitalisations in Europe, creating an annual average cost of 1,583 EUR per patient.

Indoor Quality

The World Health Organisation (WHO) defines air quality as the level of “contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural properties of the atmosphere”. The effects of indoor air pollution can be notably pronounced in specific populations, either due to higher exposure or due to increased susceptibility to certain pollutants. Children, patients living with respiratory and allergic diseases and those with a low socioeconomic background are particularly vulnerable to the effects of pollution.

In 2020, there were around 93.3 million children and teenagers enrolled at school in the EU-27, and primary school children represented the most populous group of students (23.3 million children). This specific group of children spends over 1,000 hours per year at school. Thus, the classroom is only second, after home, in time potentially exposed to pollutants and the only one in which public health measures can be directly implemented.

Several studies have addressed the relationship between indoor air quality and health in schoolchildren, confirming that various chemical pollutants and bio contaminants are found in classrooms, sometimes at elevated concentrations, often higher than outdoor levels and above existing guideline values. Indoor air quality in school buildings has been shown to be a complex function of outdoor air pollution, building characteristics, children’s activities, operation and management practices (including cleaning, maintenance), and ventilation strategies. Poor indoor air quality can impact health, school attendance, and academic performance.

Up to 1 in 4 school-age children have allergies or asthma, which are the leading causes of school absenteeism. There is no doubt that indoor exposure to allergens common in schools (such as dust mites, molds, pollen, pests) can trigger allergy/asthma symptoms. There is also evidence that exposure to diesel exhaust from vehicles entering indoor spaces through open windows, may exacerbate respiratory problems. Further aggravating the problem, young children are particularly susceptible to viral respiratory infections, in most cases due to rhinoviruses (RV). The classroom is the main field of transmission of viral infections, that then spread in the community, affecting older individuals, and resulting in considerable morbidity and mortality. Children with allergies and asthma are particularly susceptible, experiencing exacerbations of their disease and allowing increased spread of the virus. This is a major concern and cannot be overlooked, in the context of the COVID-19 pandemic. Viral bio contaminants are notorious in triggering hyper-reactivity towards other irritants, such as allergens or chemical pollutants.

The list of indoor air pollutants that impact on health is long and expanding. Nevertheless, health effects very often result from repeated, complex exposures to both chemical and biological pollutants; it is clear, but not sufficiently understood, that interactions between different pollutants multiply their health impacts. In the past years, different research studies have already found a link between air pollutants and health, but further research studies is needed to investigate the eventual modification of chemical air pollutants induced by indoor allergens.

Approach and Impact


SynAir -G has three main objectives:

  1. Generate new knowledge on chemical and biological indoor air pollutant and their main sources.
  2. Develop user and environmentally friendly solutions for indoor air quality monitoring and timely intervention, including personalisation for most vulnerable populations.
  3. Publish the generated knowledge and possible solutions, in accessible and actionable formats, including database, guidelines, and air quality standards. This dissemination will be targeted to public authorities, policy makers, consumer protection entities, patients’ associations, and society in general.

The SynAir-G project plans to achieve these three aims through the description, quantification, and mitigation of the health effects of synergising biological and chemical pollutants in real-life. This will be possible by using the following components:

  • An adequate range of sensors that can accurately and concurrently survey the wide range of chemical and biological pollutants.
  • In parallel, detailed, and relevant health outcomes need to be obtained from an appropriate population in real-life settings across multiple socioeconomic backgrounds in Europe.
  • Analytical models capable of correlating the complex exposures and dynamic outcomes, reaching conclusions and acting in near-real-time
  • Efficient mitigation strategies


After the completion of SynAir-G project, we envision:

  • Robust scientific evidence about the synergies between air pollutants and allergens in indoor spaces,
  • Increased interest and importance given to research about indoor air quality and allergens in public spaces
  • Implementation of informed and preventative European policies addressing air quality in schools,
  • Increased awareness of the impact of indoor quality on education,
  • Clear guidelines on how to create cleaner indoor spaces in schools,
  • Reduced risk of exacerbations in schools for students living with asthma and allergy