Atopic diseases, which include eczema, allergic rhinitis, asthma, and food allergy, are closely linked to allergies against airborne particles, such as pollen, dust, mold, or animal dander, or foodstuffs like peanut, milk, soy, shellfish, or wheat. Until the early 20th century, allergy was thought to be a rare disease. But since in the 1920s to 1930s and especially since the second half of the 20th century, the prevalence of allergies has exploded in Western societies. For example, the European Academy of Allergy and Clinical Immunology estimates that half of the population of the EU will have allergies by 2025: an increase by 20 percent points since 2015. Similarly, a survey from 2020 estimated that approximately 100 million (30%) Americans of all ages have allergies today.