Both genes and the environment shape human health and disease. Although IgE-mediated allergic diseases (atopic diseases) have a genetic component and are more prevalent in individuals with a family history of allergic disease, the observed rapid increases in allergic diseases suggest that environmental factors are the predominant driving forces behind these increases rather than genetic alterations. 1,2 Common atopic diseases include atopic dermatitis, food allergy, allergic rhinitis, and allergic asthma. Human diets and lifestyle have undergone major alterations. The exposome, which is the sum total of all the exposures of an individual in a lifetime, has undergone major shifts in the last few decades, affecting human health and disease. A number of environmental factors have been implicated in the increased prevalence of allergic diseases. Predominant among them are increased exposure to pollutants and decreased exposure to microbes and parasitic infections. Air pollution has increased significantly in the last few decades. The hygiene hypothesis suggests that increased hygiene and lack of exposure to microbes and parasitic infections at an early age prevents the necessary stimulus to train the immune system to develop tolerogenic responses. Lifestyle factors,