Silvia Ruiz

Effects of Intermittent Ozone Exposure on Peak Expiratory Flow and Respiratory Symptoms among Asthmatic Children in Mexico City

In a panel study of Mexican children (5-13 y of age) with mild asthma, the authors studied the relationship between ozone exposure and the course of childhood asthma. Decrements in peak expiratory flow rate were associated with ozone, and respiratory symptoms were associated with both ozone level and ambient particulate matter (< 10 microm) level. After the authors adjusted for minimum temperature and autocorrelation in the data, they determined that an increase of 50 ppb in a daily ozone 1-h maximum was related to an 8% increase in cough (95% confidence interval = 2, 15); a 24% increase in phlegm (95% confidence interval = 13, 35); and an 11% increase in low respiratory symptoms index (95% confidence interval = 5, 19). The authors concluded that children with mild asthma who resided in the south of Mexico City were affected adversely by the high ozone ambient levels observed in this area.

Prevalence of Asthma and Other Childhood Allergies in Brazilian Schoolchildren

We determined the prevalence of asthma, rhinitis, and eczema among Brazilian children using the standardized protocol of the International Study on Asthma and Allergies in Childhood (ISAAC) to facilitate the comparison of our results with other studies using the ISAAC methodology. We conducted a cross-sectional study from June to October 1994 to determine the prevalence of asthma, rhinitis, and eczema in 5182 school children aged 7-8 years and 13-14 years residing in the Brazilian towns of Santa Maria and Itabira (iron-mining cities located in Minas Gerais). Parents completed questionnaires at their childs school in the presence of trained interviewers. The cumulative prevalence of doctor-diagnosed asthma was 4.6% for all ages with no significant difference between the age groups. In general, there was a higher prevalence of symptoms in the younger age group than the older. The prevalence of wheezing in the previous 12 months was 14.3% (7-8 years old) and 9.3% (13-14 years old) (p < 0.01), of chronic cough in the previous 12 months was 25.6% (7-8 years old) and 22.1% (13-14 years old) (p < 0.01), and of nighttime cough in the previous 12 months was 22.3% (7-8 years old) and 19.4% (13-14 years old) (p < 0.05). Overall the prevalences of asthma and wheezing symptoms in the previous 12 months were higher for boys than girls (5.2% vs. 3.9% for asthma, p < 0.01, and 13.2% vs. 10.6% for wheezing, p < 0.01, respectively). These results suggest that asthma-related respiratory illnesses affect a substantial part of the childhood population in Itabira and Santa Maria, Minas Gerais. Some factors such as male gender and younger age may be associated with an increase risk for chronic respiratory symptoms. Prevalences of asthma and allergic diseases in these Brazilian cities on the basis of self-reporting of symptoms and of ones medical history may more accurately portray the true prevalence of asthma than the use of medical records.

Efectos agudos de las partículas respirables y del dióxido de azufre sobre la salud respiratoria en niños del área industrial de Puchuncaví, Chile

This study investigated the acute effect of air pollution on the respiratory health of children living in the industrial area of Puchuncaví, in Region V of Chile. The 114 children studied were from 6 to 12 years old; 57 of them had chronic respiratory symptoms and 57 did not. Each day for 66 days the air was checked for levels of sulfur dioxide (SO2) and of breathable particles that were < 10 microns (PM10). The children were selected and classified according to their susceptibility to chronic respiratory disease by means of a questionnaire used with 882 children living within the area of the emissions from a copper foundry and a thermoelectric plant. Each day, each studied childs peak expiratory flow (PEF) and incidence of respiratory symptoms were checked and recorded. Using regression models (generalized estimation equations), estimates were made of the association of SO2 and PM10 levels with PEF and the incidence of cough, expectoration, episodes of wheezing, dyspnea, and use of bronchodilators. Among the children who were initially symptomatic, an increase of 50 micrograms/m3 in the daily mean level of SO2 caused a reduction of -1.42 L/min (95% confidence interval (95% CI): -2.84 to -0.71) in the PEF of the following day. An increase of 30 micrograms/m3 in the cumulative concentration of PM10 over three days produced a PEF reduction of -2.84 L/min (95% CI: -4.26 to 0.00). With respect to symptoms, an increase of 30 micrograms/m3 in the weekly mean level of PM10 was related with a 26% increase (odds ratio (OR) = 1.26; 95% CI: 1.01 to 1.57) in the incidence of cough and of 23% (OR = 1.23; 95% CI: 1.00 to 1.50) in the incidence of expectoration. An increase of 50 micrograms/m3 in the mean level of SO2 for three days was associated with a 5% increase (OR = 1.05; 95% CI: 1.00 to 1.10) in the incidence of expectoration. An increase of 30 micrograms/m3 in the daily average of PM10 increased the use of bronchodilators two days later by 10% (OR = 1.10; 95% CI: 1.03 to 1.18). Among the initially asymptomatic children, a significant effect from PM10 exposure was found after an increase of 30 micrograms/m3 in the mean daily PM10 level, with a reduction of -1.34 L/min (95% CI: -2.68 to -0.67) in the PEF of the following day. A similar increase in the cumulative exposure over three days was associated with an increase of 9% in the incidence of episodes of wheezing (OR = 1.09; 95% CI: 1.01 to 1.31). It is concluded that high levels of PM10 and SO2 affect the respiratory health of children living in the industrial area of Puchuncaví.Se investigo el efecto agudo de la contaminacion atmosferica sobre la salud respiratoria en 114 ninos de 6 a 12 anos de edad residentes en la zona industrial de Puchuncavi, V Region de Chile: 57 con sintomas respiratorios cronicos y 57 asintomaticos. Durante 66 dias se midieron diariamente los niveles de particulas respirables de tamano < 10 mym (PM10) y de dioxido de azufre (SO2) en el aire. Los participantes fueron seleccionados y clasificados segun su susceptibilidad a la enfermedad respiratoria cronica, para lo cual se utilizo un cuestionario de sintomas respiratorios aplicado a un total de 882 ninos residentes en el area de influencia de las emisiones de una fundicion de cobre y de una central termoelectrica. Diariamente se registraron el flujo espiratorio maximo (FEM) y la incidencia de sintomas respiratorios. La asociacion de los niveles de PM10 y SO2 con el FEM y la incidencia de tos, expectoracion, sibilancias, disnea y uso de broncodilatadores fue estimada por modelos de regresion (ecuaciones estimativas generalizadas). En los ninos inicialmente sintomaticos, un incremento de 50 myg/m³ en el nivel medio diario de SO2 dio lugar a una reduccion de -1,42 L/min (intervalo de confianza de 95% (IC95%): -2,84 a -0,71) en el FEM del dia siguiente, mientras que un aumento de 30 myg/m³ en la concentracion acumulada de tres dias de PM10 produjo una disminucion de -2,84 L/min (IC95%: -4,26 a 0,00). Con respecto a los sintomas, un aumento de 30 myg/m³ en el nivel medio semanal de PM10 se relaciono con un incremento de 26% (razon de posibilidades (RP) = 1,26; IC95%: 1,01 a 1,57) en la incidencia de tos y de 23% (RP = 1,23; IC95%: 1,00 a 1,50) en la incidencia de expectoracion, un aumento de 50 myg/m³ en el nivel medio de SO2 durante tres dias se asocio a un incremento de 5% (RP = 1,05; IC95%: 1,00 a 1,10) en la incidencia de expectoracion y un aumento de 30 (myg/m³ en el promedio diario de PM10 incremento el uso de broncodilatadores dos dias mas tarde en 10% (RP = 1,10; IC95%: 1,03 a 1,18). En los ninos inicialmente asintomaticos solo se registraron efectos significativos por la exposicion a las PM10: tras un incremento de 30 myg/m³ en su nivel medio diario se observo una reduccion de -1,34 L/min (IC95%: -2,68 a -0,67) en el FEM del dia siguiente y un incremento similar en la exposicion acumulada de tres dias se asocio a un aumento de 9% en la incidencia de sibilancias (RP = 1,09; IC95%: 1,01 a 1,31). Se concluye que la salud respiratoria de los ninos residentes en el area industrial de Puchuncavi se ve afectada por los altos niveles de PM10 y SO2.