A new study, published in the Journal of Allergy and Clinical Immunology, examines how early childhood exposure to allergens and bacteria affects later presentation of recurrent wheeze and atopy. According to the American Academy of Allergy Asthma and Immunology, atopy is the tendency to develop allergic diseases such as allergic rhinitis, asthma and eczema. Atopy is typically associated with heightened immune responses to common allergens, especially inhaled allergens and food allergens.

Participants in the study with highest exposure to allergens and bacteria in early childhood, such as those in inner-city settings, were least likely to have allergy issues later in life. The study found that exposure to high levels of certain allergens and bacteria in early life might be beneficial and suggest new preventive strategies for wheezing and allergic diseases.

An analysis of the study in HealthDay asserts that a too-clean home may in fact be dangerous for children. The findings support the “hygiene hypothesis,” which holds that children in overly clean houses are more apt to suffer allergies because their bodies do not have the opportunity to develop appropriate responses to allergens.

Allergies and hay fever affect millions in the U.S.  The U.S. Centers for Disease Control and Prevention (CDC) reports that in the last 12 months, 17.6 million adults and 6.6 million children were diagnosed with hay fever.  As a result of allergic rhinitis, there were 11.1 million visits to doctors in which that was the primary diagnosis.