The county of Canoas, constituent of the metropolitan region of Porto Alegre, is among the most populous cities of RS and is affected by several meteorological phenomena, such as cold fronts, throughout the year. Therefore, this study aims to determine the meteorological conditions conducive to the increase in the number of daily respiratory diseases due to asthma or bronchitis in children. Were used data from outpatient consultations of children from 0 to 5 years in Basic Health Units in the city of Canoas between January 2005 and September 2008, as well as daily meteorological data on temperature, relative humidity, atmospheric pressure, wind speed and cloudiness, at 12 and 18Z, accompanied by human thermal comfort indexes (HTCI; calculated). We defined 42 days with excessive (peak) consultations. The monthly distribution of these days showed that 81% occurred in winter, being 43% in July and 24% in June, while summer was the only season that did not have days with peak consultations. The number of outpatient care showed a statistically significant (negative) correlation with the temperature and HTCI from three days previous the consultation date for the 12Z and 18Z, occurring the same with atmospheric pressure, however the correlation was positive, with respect to relative humidity, the (positive) correlation was significant only at 12Z. The highest correlations occurred on the day of the consultation, in the morning, with temperature, relative humidity, atmospheric pressure and wind speed, and for two before consultation with HTCI. Therefore, increases in the consultations were associated with the fall in temperature and rise in relative humidity and atmospheric pressure, in the morning. Around 55% of the days of the period were associated, at 12Z, with the sensation of cold. Analyzing all the visits of this period, it was found that more than 65% occurred under the sensation of cold, while for the days with peak of consultations, this sensation prevails for about 90% of the attendances, being approximately 40% under the feeling from 4 to 12oC. After reproducing air masses causing atmospheric conditions favorable to respiratory complications, it was found that 45% of the masses arrived, at 12Z, in the municipality of Canoas by the direction SW, and 19% and 14%, respectively, by the southern and west, the other directions were less representative.
