Respiratory tract and systemic responses in clinically healthy children exposed to the atmospheric pollution in southwest Mexico City

Lifelong exposures to ambient air pollutants of clinically healthy children may have clinically important consequences. Southwest Metropolitan Mexico City (SWMMC) children are chronically and sequentially exposed to complex mixtures of air pollutants, predominantly ozone and particulate matter. We have investigated the association between exposure to the SWMMC atmosphere and nasal gross mucosal abnormalities, hyperinflation and interstitial markings assessed in chest-x rays, lung function changes, as well as serum cytokines in a cohort of 174 children ages 5–17 years. These observations were compared to a control group of 19 children residents in a low-polluted area. Children in the control group have no nasal lesions and only one child showed an abnormal chest x ray. Twenty two per cent of SWMMC children exhibited nasal mucosal abnormalities, 67% hyperinflation and 49% interstitial markings. Ten percent had spirometric abnormalities primarily a mild obstructive or restrictive pattern. We found a significant negative association between the key spirometric variables forced expiratory vital capacity (FVC) and forced expiratory volume in 1 second (FEV₁) and increases in concentrations of ozone and PM₁₀. Peripheral blood smear findings included toxic granulations in PMN, schistocytes, and rare giant platelets. SWMMC children had significantly less IL8 serum concentrations when compared to controls. Chronic inhalation of a complex mixture of air pollutants is associated with respiratory tract damage in healthy children living in SWMMC. The radiological abnormalities and spirometric changes suggest the development of small airway disease. Exposed children have a down-regulation of IL8 and this imbalance is most likely the result of the attempts of healthy children to limit the inflammatory responses in the respiratory tract. Thus, these children are potentially at risk of developing chronic lung disease and other systemic effects later in life.