Surrounding Greenness and Exposure to Air Pollution During Pregnancy: An Analysis of Personal Monitoring Data

BACKGROUND: Green spaces are reported to improve health status, including beneficial effects on pregnancy outcomes. Despite the suggestions of air pollution related health benefits of green spaces, there is no available evidence on the impact of greenness on personal exposure to air pollution. OBJECTIVES: We investigated the association between surrounding greenness and personal exposure to air pollution among pregnant women and to explore the potential mechanisms, if any, behind this association. METHODS: In total, 65 rounds of sampling were carried out for 54 pregnant women who resided in Barcelona during 2008-2009. Each round consisted of a 2-day measurement of particulate matter with aerodynamic diameter <= 2.5 mu m (PM2.5) and a 1-week measurement of nitric oxides collected simultaneously at both the personal and microenvironmental levels. The study participants were also asked to fill out a time microenvironment activity diary during the sampling period. We used satellite retrievals to determine the surrounding greenness as the average of Normalized Difference Vegetation Index (NDVI) in a buffer of 100 m around each maternal residential address. We estimated the impact of surrounding greenness on personal exposure levels, home-outdoor and home-indoor pollutant levels, and maternal time-activity. RESULTS: Higher residential surrounding greenness was associated with lower personal, home-indoor, and home-outdoor PM2.5 levels, and more time spent at home-outdoor. CONCLUSIONS: We found lower levels of personal exposure to air pollution among pregnant women residing in greener areas. This finding may be partly explained by lower home-indoor pollutant levels and more time spent in less polluted home-outdoor environment by pregnant women in greener areas.