The neighbourhood natural environment is associated with asthma in children: A birth cohort study

Background A lower exposure to the natural environment has been hypothesized to adversely affect the human microbiome and its immunomodulatory capacity. However, the underlying effects of this hypothesis are still not understood. We aimed to evaluate the effect of early-life exposure to greenness and species richness on the development of allergic diseases and asthma in children. Methods A longitudinal study was conducted comprising 1050 children from a population-based birth cohort recruited in Portugal. Residential normalized difference vegetation index (NDVI) and species richness index (SRI) were assessed at baseline to estimate their association with allergic diseases and asthma at the ages of 4 and 7. Results Significant predisposing associations were observed between the exposure to species richness at baseline and the onset of asthma and wheezing at the age of 7. Children living in neighbourhoods surrounded by high levels of SRI were at a significantly higher risk developing allergic sensitization(OR [95% CI] = 2.00 [1.04:3.86] at age 4; 2.35 [1.20:4.63] at age 7). Living surrounded by greener environments was significantly associated with a lower prevalence of asthma and rhinitis at the age of 7(0.41 [0.18:0.97] and 0.37 [0.15:0.93], respectively). Conclusions Living in close proximity to a greener environment at birth has a protective effect on the development of allergic diseases and asthma at the age of 7. Conversely, living in neighbourhoods with a high number of fauna species appears to be associated with a higher risk for allergy, asthma and wheezing. The EXALAR 21 project was funded by the European Regional Development Fund (FEDER), through the Competitiveness and Internationalization Operational Programme, and by national funding from the Foundation for Science and Technology (FCT) under the scope of the project info:eu-repo/grantAgreement/FCT/9471 - RIDTI/PTDC/GES-AMB/30193/2017/PT (POCI-01-0145-FEDER-030193, 02/SAICT/2017 - Project nº 30193). This study was also funded by FEDER through the Operational Programme Competitiveness and Internationalization and national funding from the Foundation for Science and Technology – FCT (Portuguese Ministry of Science, Technology and Higher Education) under the Unidade de InvestigaçãoemEpidemiologia - Instituto de SaúdePública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref. UID/DTP/04750/2019). Ana Isabel Ribeiro was supported by National Funds through FCT, under the programme of ‘Stimulus of Scientific Employment – Individual Support’ within the contract info:eu-repo/grantAgreement/FCT/CEEC IND 2018/CEECIND/02386/2018/CP1538/CT0001/PT.