City air is harmful to people with allergies

Climate change and the characteristics of modern urbanisation have meant that the allergy season in Luxembourg now begins much earlier – in some cases as early as December or January – and lasts longer than usual. According to a large-scale study conducted by the Luxembourg Institute of Health (LIH) in Esch-sur-Alzette, more than 40% of the country’s adult population currently suffers from various allergic reactions, primarily affecting the respiratory tract, lungs and nasopharynx.

As Dr Annette Kuehn, a leading researcher at the institute, explains, a key factor in the worsening of the problem has been the anthropogenic stress experienced by urban green spaces. Trees in major cities, constantly exposed to polluted air and exhaust fumes, alter their biological activity and begin to produce significantly more pollen than plants in the wild. The already strained environmental conditions are exacerbated by dry and warm weather, which facilitates the transport of allergens. However, the human body reacts not to the pollen itself, but to the protein substances it contains. The situation is further complicated in the autumn: according to a Norwegian study cited by LIH, parasitic fungi become active on birch trees at this time of year, acting as an additional trigger for flare-ups.

In addition to climate, the rise in disease incidence is directly linked to modern lifestyles, dietary patterns and the overall decline in biodiversity in people’s everyday environments. As a result, the immune system loses its ability to respond adequately to external stimuli. As a preventive measure, experts recommend maintaining a healthy diet from infancy and ensuring regular exposure to the natural microbial environment, which allows the immune system to ‘learn’ the correct responses.

Meanwhile, a research team led by Dr Christiane Hilger has focused on studying household allergens as part of a major European project bringing together clinical centres from eight countries. The scientists are using an innovative biochip capable of recognising 160 different antigens, including microparticles of animal hair, dust mites and mould. Initial blood tests on patients revealed a high degree of cross-reactivity: one in two participants reacts to several types of animals, and two-thirds of them also suffer from pollen and house dust mite allergies.