Early pollution exposure has long-lasting respiratory effects

Exposure to traffic-related pollution during the first year of life continues to affect lung function at age 8 years, show the results of a Swedish study.

"Our findings provide further support that early life exposure has long-lasting impact on the lung function development," say Göran Pershagen (Karolinska Institute, Stockholm, Sweden) and colleagues.

The study reports the follow up of a birth cohort of 4089 children recruited between 1994 and 1996. The children were assessed by questionnaire about their respiratory health and allergic diseases at 1, 2, 4, and 8 years of age. The authors estimated their exposure to PM₁₀ (particulate matter with an aerodynamic diameter <10 µm) through dispersion modeling at residential, daycare, and school locations.

Exposure to PM₁₀ during the first year of life was associated with a reduction in forced expiratory volume in 1 second (FEV₁) at age 8 years of 59.3 mL between the 5th and the 95th percentiles of exposure.

Furthermore, the authors calculated that early exposure to traffic PM₁₀ in the 95th versus the 5th percentile significantly increased the odds for an FEV₁ of less than 85% predicted by 6.1-fold at 8 years.

Pershagen and colleagues also observed an effect of particulate matter exposure on forced vital capacity (FVC) but this did not reach statistical significance. They say that this shows that their findings reflect changes to airway mechanics as opposed to lung size.

Importantly, the authors assessed short- and long-term exposure simultaneously, and demonstrated that their findings were not confounded by short-term exposure.

The study adds to evidence of an important influence of early air pollution exposure on lung function in later life. This could be because the alveoli continue to develop during childhood and adolescence, say the authors.

Writing in the American Journal of Respiratory and Critical Care Medicine, they conclude that their findings could have important consequences for public health: "From an individual perspective the estimated effect on lung function seen in our study is rather small, but even a slight shift in the population distribution of lung function can substantially increase the prevalence of subjects exhibiting respiratory function below clinical thresholds."

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