Environment and development of respiratory allergy. II. Indoors.

Even if it is difficult to obtain correct epidemiological evidence, there is a body of evidence which suggests that the frequency of allergic respiratory diseases is increasing. The majority of atopic patients, in particular in childhood and adolescence, develop immunoglobulin E (IgE) antibodies with clinical symptoms to aeroallergens, such as those derived from house dust mites, pollens and pets. Since, in the economically-developed countries individuals spend most of their time indoors (home, school and workplace), indoor pollutants (tobacco smoke etc.) and allergens (house dust mite, cats, etc.) are the most important source of exposure. Indoor allergens are associated with a wide variety of particles in a broad size range, only some of which are microscopically identifiable, culturable, or detectable with existing immunoassay. Evaluation of indoor allergens requires both air and source sampling, and several different analytical techniques. It is likely that the increased prevalence of allergy and asthma may be caused in the indoor environment by the synergistic action of air pollution (in particular derived from tobacco smoking) with allergic sensitization. Passive smoking in infancy has also been involved in the airways allergic sensitization to common aeroallergens.