[Effect of the environment on the development of respiratory allergies]

Allergy reactions may be regarded as resulting from exposure to allergens of subjects who are genetically predisposed to synthesize IgE. The presence of allergens in the environment is necessary to acquire sensitization. With some allergens, sensitization seems to develop very rapidly. The introduction or presence in the environment of certain allergens, such as house dust mites, may increase the prevalence of asthma. Despite conflicting reports, in atopic subjects exposure to pet animals also is a risk factor. Introducing foreign proteins prematurely into infant's food has been considered a factor that facilitates the development of allergic diseases. Contact with occupational allergens results in allergic manifestations in less than one-third of the subjects exposed, which suggests that genetic factors play a predisposing role. Beside exposure to allergens, non-specific environmental factors, such as chronic inhalation of tobacco smoke or atmospheric pollutants (e.g. ozone, SO2, NO2, particles of burnt fuels) might contribute to sensitization. The part played by viral infections (RSV or influenza virus) in the triggering of allergic diseases has often been reported. Interactions between irritants and allergens may encourage the development of respiratory allergy.