Objective: To analyze the prevalence of asthma and asthma symptoms in students of two distinct age brackets residing in the city of Tangará da Serra, Brazil. Methods: Cross-sectional, population-based study of the prevalence of asthma in children from 6 to 7 years of age and adolescents from 13 to 14, using the standardized International Study of Asthma and Allergies in Childhood, phase 1 questionnaire, validated for use in Brazil. Students who responded affirmatively to question 2 (presence of wheezing in the preceding 12 months) were classified as suffering from asthma. Results: The study comprised 3,362 students, of whom 1,634 (48.6%) were children and 1,728 (51.4%) were adolescents. Of the 1,634 children, 816 (49.9%) were male and 818 (50.1%) were female. Of the 1,728 adolescents, 773 (45.0%) were male and 955 (55.0%) were female. The prevalence of asthma among the children was 25.2%, whereas that among the adolescents was 15.9% (χ2 = 8.34; p = 0.00). The children presented higher prevalences of the following symptoms of asthma than did the adolescents: wheezing ever (54.3%), nocturnal dry cough (43.9%), wheezing in the preceding 12 months (25.2%), and from 1 to 3 attacks of wheezing in the preceding 12 months (19.1%). There were no differences between the two groups regarding physician-diagnosed asthma (approximately 4.5%). There were no statistical differences regarding the prevalence of asthma by gender in the two groups. Conclusions: Tangará da Serra has a high prevalence of asthma in children and adolescents, and this result is compatible with other studies carried out in Brazil and Latin America using the same methodology.

Keywords: Asthma/epidemiology; Child; Adolescent.

Objective: To analyze hospitalizations for respiratory diseases among children under 15 years of age in an area with high levels of environmental pollution. Methods: A cross-sectional study of hospitalizations due to respiratory diseases of patients residing in the city of Tangará da Serra, located in the state of Mato Grosso (Brazilian Amazon region), from 2000 to 2005. Data on hospital admissions were obtained from the Brazilian Unified Health Care System and from Brazilian Institute of Geography and Statistics population estimates. Results: In 2005, the rate of hospitalization for respiratory diseases among children under 15 years of age in the microregion of Tangará da Serra was 70.1/1,000 children. Between 2000 and 2005, there were 12,777 such admissions, of which 8,142 (63.7%) were for respiratory diseases. During the dry season (May to October), the rate of admissions for respiratory diseases was 10% higher than during the rainy season (November to April). The principal causes of admission included pneumonia (90.7%) and respiratory insufficiency (8.5%). Admissions of children under 5 years of age for pneumonia were 4 times the expected number for the city. Children under 12 months of age were the most frequently hospitalized, with an average increase of 32.4 admissions per 1,000 children per year. Conclusions: Tangará da Serra presented a high number of pediatric admissions for respiratory diseases. Therefore, it is logical to consider it a priority area for investigation and monitoring of the environmental risk factors for such diseases.

Keywords: Respiratory tract diseases; Pneumonia; Hospitalization; Climate; Air pollution/Brazil.