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Air pollution exposure during pregnancy has been linked to a wide range of negative health effects. NO₂, a traffic pollution marker, and benzene, an industrial pollution indicator, stand out among the types of air pollution linked to these effects. The aim of this work is to show the methodology used to assign exposure levels for both pollutants and preliminary reports in the INMA (Environment and Childhood) Asturias cohort in Spain. This cohort consists of 494 pregnant women and their children, who have been recruited and followed since 2004. Air pollution levels were measured at 67 points by means of passive samplers. The mean NO₂ measured value was 21.2 μg m⁻³ (range 3.5 μg m⁻³ to 44.5 μg m⁻³), and the mean benzene value was 2.72 μg m⁻³ (range 0.18 μg m⁻³ to 9.17 μg m⁻³) at urban sampling points and 0.64 μg m⁻³ (range 0.04 μg m⁻³ to 2.62 μg m⁻³) in rural locations. The Pearson correlation coefficient among pollutants was 0.42. Land Use Regression models were built to predict exposure at the homes of pregnant women. Altitude, road distances and land use were part of the models. The percent of explained variance was 52% for NO₂ and 73% for benzene in the urban zones. No residual autocorrelation was found. Predictions were corrected based on the Air Quality Network of the Principality of Asturias taking into account pregnancy seasonality. Exposure indicators were determined for each term and for the entire pregnancy for each woman. Values for urban locations were higher than those for rural and benzene estimations for 5% of the cohort women were above the European Union annual limit value. Air pollution exposure for the INMA-Asturias cohort clearly depends on the place of residence. In particular, benzene concentrations are remarkably high if an individual lives in an urban and industrial area, which is an issue of management intervention and regulatory concern. Exposure assessment for different pollutants will allow us to evaluate potential adverse effects in foetal and infant health caused by air pollution.
