Does residential mobility during pregnancy induce exposure misclassification for air pollution?

Olivier Blanchard,Séverine Deguen,Wahida Kihal-Talantikite,Denis Zmirou-Navier,Romain François

doi:10.1186/s12940-018-0416-8

Abstract

BackgroundPrenatal exposure to outdoor air pollution has been shown to have health effects in many studies; low birth weight, preterm delivery, small for gestational age, and stillbirth are the most often cited. However, exposure of pregnant women is difficult to quantify, especially with regard to their mobility, which is rarely taken into account in epidemiological studies. This study aimed to assess the impact of mobility of pregnant women living in Paris, France, on their exposure estimates to nitrogen dioxide (NO2).MethodsA total of 486 pregnant women were recruited in 5 maternity hospitals in Paris between January and April 2016. A questionnaire was used to collect mothers’ characteristics (demography, education, etc.) and to assess their daily mobility during pregnancy (time spent at work, commuting time and mode used to move from residential to occupational places). Daily NO2 concentrations were estimated based on the combination of annual average concentrations modeled at the census block scale and daily concentrations measured from fixed monitoring stations. Different models were used to compare the exposure of pregnant women in residential and occupational places, also taking into account travel time and travel mode. The socioeconomic profile of the census blocks was characterized using a multi-component index.ResultsDuring the first trimester of pregnancy, women living in the least deprived census blocks were exposed to higher concentrations of NO2 than those living in the most deprived ones. Occupational mobility had a small impact on exposure levels (average increase after taking account of mobility: + 0.52 μg/m3) which was not related to the socioeconomic profile of the women. The commuting mode made a greater difference (+ 1.46 μg/m3 on average), in particular among women living in the most deprived census blocks.ConclusionsOur study illustrates that air pollution exposure can be underestimated when ignoring occupational mobility and commuting mode of pregnant women. This effect might be differential according to the neighborhood deprivation profile.

Highlights

Prenatal exposure to outdoor air pollution has been shown to have health effects in many studies; low birth weight, preterm delivery, small for gestational age, and stillbirth are the most often cited
Our study aims to assess the impact of daily mobility on exposure to NO2 of pregnant women living in Paris, France, in particular through integrating the time spent at work locations and while commuting
The majority of women traveled by metro to move from their residential to their occupational census block; the daily commuting time was equal to 45 min on average; it decreases

Summary

Introduction

Prenatal exposure to outdoor air pollution has been shown to have health effects in many studies; low birth weight, preterm delivery, small for gestational age, and stillbirth are the most often cited. Exposure of pregnant women is difficult to quantify, especially with regard to their mobility, which is rarely taken into account in epidemiological studies. This study aimed to assess the impact of mobility of pregnant women living in Paris, France, on their exposure estimates to nitrogen dioxide (NO2). Exposure to nitrogen dioxide (NO2) in Montreal, Canada, show significant differences between dynamic and static approaches to exposure assessment [18]. When considering their mobility across the city, the authors observed that most individuals had a higher daily exposure compared to the daily average concentration at their home location.

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