Environmental factors affecting children's respiratory health in the first years of life: a review of the scientific literature.

The aim of this paper is to quantitatively summarize the original articles on the relationship between environmental hazards and respiratory health in young children. A search was carried out in the main biomedical bibliographical sources in December 2006 and then the results were updated in June 2007. The study period covered 11 years (1996-2006). The information was assessed by reviewing the abstracts. Six hundred and forty documents were recovered. Documents from the United States accounted for 23.5% of articles. The production tended to increase over the study period. The factor most widely studied was air pollution, with outdoor air pollution being studied more (just over 50% of articles) than indoor air pollution (40%). Asthma was the most often studied condition (75% of articles). In a third of the cases, the information was obtained from hospital or health center records, and in 20% from questionnaires. The main diagnostic criterion was clinical. Infection of the inferior respiratory tracts predominated in children less than 3 years of age. An awareness of the role played by pollution and environmental hazards is fundamental in the management and prevention of respiratory problems in childhood, and this is reflected in the literature reviewed. However, very few synthesis studies have been carried out on this matter.