Air pollution link to early childhood pneumonia

European research shows that exposure to elevated levels of air pollutants is associated with an increased risk for pneumonia before the age of 3 years, and particularly in the first year of life.

However, the researchers did not find strong evidence of a link between pollution and other respiratory infections, including otitis media and croup.

Joachim Heinrisch (German Research Centre for Environmental Health, Munich) and colleagues analyzed data from 10 birth cohorts, as part of the European Study of Cohorts of Air Pollution Effects (ESCAPE) project.

Their data included 16,059 children and the cumulative incidence of pneumonia before the age of 3 years was 1.5–7.9%, of otitis media was 21.8–50.0%, and of croup was 10.6–12.9%.

The team found that, after adjustment for confounders, the odds for pneumonia were significantly greater with increasing exposure to several pollutants, including NO₂, NO_x, particulate matter up to 10 µm (PM₁₀), and coarse PM (PM_2.5-10). Additionally, increasing proximity to the nearest street or major streets was also associated with the likelihood of pneumonia.

However, the only other significant association found was between otitis media and NO₂, for which the odds increased 1.09-fold for every 10 µg/m³ increase.

Additionally, the authors report that the association between pneumonia and air pollutant exposure was particularly strong during the first year of life. For example, every 5 µg/m³ increase in PM_2.5 was associated with a 4.06-fold increased odds for pneumonia in the first year of life, and a nonsignificant 2.65-fold increased odds in the second. Indeed, in the second year of life, only NO₂ and NO_x exposure were significantly related to pneumonia risk, compared with all measures of pollution in the first year.

“This finding could highlight a unique period of susceptibility when children are at increased risk of respiratory infections due to air pollution,” comment Heinrisch et al in Environmental Health Perspectives.

They conclude: “Policies aimed at reducing air pollution may be successful in reducing the overall burden of pneumonia in early childhood.”

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