RESUMO
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.
Assuntos
Asma/fisiopatologia , Exposição Ambiental/efeitos adversos , Oxidantes Fotoquímicos/efeitos adversos , Ozônio/efeitos adversos , Doença Aguda , Adolescente , Asma/complicações , Criança , Pré-Escolar , Tosse/etiologia , Exposição Ambiental/análise , Feminino , Humanos , Estudos Longitudinais , Masculino , México , Oxidantes Fotoquímicos/análise , Ozônio/análise , Pico do Fluxo Expiratório , Prevalência , Escarro , Saúde da População UrbanaRESUMO
The relation between air pollution and the exacerbation of childhood asthma was studied in a panel of 71 children (aged 5 to 7 yr) with mild asthma who resided in the northern part of mexico City. During the follow-up, ambient measures of particulate matter less than 10 microns (PM10, 24-h average) and ozone (1-h maximum) frequently exceeded the Mexican standards for these contaminants. The peak expiratory flow rate (PEFR) was strongly associated with PM10 levels and marginally with ozone levels. Respiratory symptoms (coughing, phlegm production, wheezing, and difficulty breathing) were associated with both PM10 and ozone levels. An increase of 20 micrograms/m3 of PM10 was related to an 8% increase in lower respiratory illness (LRI) among children on the same day (95% confidence interval [CI] = 1.04-1.15), and an increase of 10 micrograms/m3 in the weekly mean of particulate matter less than 2.5 microns (PM2.5) was related to a 21% increase in LRI (95% CI = 1.08-1.35). A 50 parts per billion (ppb) increase in ozone was associated with a 9% increase in LRI (95% CI = 1.03-1.15) on the same day. We concluded that children with mild asthma are affected by the high ambient levels of particulate matter and ozone observed in the northern part of Mexico City.