Objectives: The development of allergic conditions is largely dependent on the interactions between genetic (individual genetic predisposition) and environmental factors (exposure to risk factors). The aim of this study was an attempt to assess the influence of selected elements of the hygiene theory in the development of allergic diseases such as allergic rhinitis and asthma. Material and Methods: The study group consisted of 5518 women and 3868 men. The method that was used was the European Community Respiratory Health Survey II and International Study of Asthma and Allergies in Childhood questionnaire validated and adapted to Central and Eastern European conditions. The project was conducted in 8 urban areas (Gdańsk, Wrocław, Poznań, Katowice, Kraków, Lublin, Białystok, Warsaw) and 1 rural area (Krasnystaw county). This study had 2 stages; the first stage involved grouping the 22 500 respondents based on their questionnaire responses with the use of a Personal Digital Assistant (PDA); the second stage involved 7000 subjects, who underwent additional assessments: skin prick tests (birch, grasses/cereals, Dermatophagoides pteronyssinus and Dermatophagoides farinae, molds [set I: Botrytis cinerea, Cladosporium herbarum, Alternaria tenuis, Curvularia lunata, Fusarium moniliforme, Helminthosporium], molds [set II: Aspergillus fumigatus, Mucor mucedo, Penicillium notatum, Pullularia pullulans, Rhizopus nigricans, Serpula lacrymans], cat, dog, molds Cladosporium herbarum, Alternaria tenuis) and spirometry tests. Results: The age at which children attend the nursery school is critical to the development of allergic diseases; in allergic rhinitis, the risk of an IgE-dependent reaction is 2 times higher in the second than in the first year of life (p = 0.00147, p < 0.05), while in asthma, having a large number of siblings increases the risk of developing obstructive disease by almost 6 times (p = 0.00316, p < 0.05).The age at which children attend the nursery school is critical to the development of allergic diseases; in allergic rhinitis, the risk of an IgE-dependent reaction is 2 times higher in the second than in the first year of life (p = 0.00147, p < 0.05), while in asthma, having a large number of siblings increases the risk of developing obstructive disease by almost 6 times (p = 0.00316, p < 0.05). Conclusions: The hygiene theory is particularly applicable and can explain the relationship of selected habits in the development of allergic diseases. Int J Occup Med Environ Health. 2023;36(1):69–83