Background and Objectives:
Environmental exposure to teratogenic factors during pregnancy has been associated with some congenital anomalies (CA). In 2015, a cluster of CA in newborns (NB) was detected in an area with high industrial density. We developed an epidemiological study to analyse the association of CA and atmospheric pollution (AP) in this area in Portugal.

Methods:
A case-control study was developed between 2016 and 2021. A multicriteria spatial analysis using Geographic Information System software was adopted to identify the AP susceptibility map. The variables included: (i) Euclidean distance to industrial units, (high(H)moderate(M)4000m); (ii) kernel estimation of industrial units density; (iii) land occupation: H susceptibility - industrial areas, roads, landfills and dumps; M susceptibility - residential areas; L susceptibility - natural, forest and agricultural areas; (iv) Euclidean distance to the main roads (H M300m); (v) areas of fog, modelled by the digital terrain model using Jenks Natural Break method. The map of AP susceptibility (High, Moderate and Low) derived from previous variables normalization, weighting and crossed in raster matrices using the weighted linear combination.

Results:
Three areas of AP susceptibility were identified, a consolidated urban, a peri-urban area and a southern zone of an urban zone. 21 cases (21%) and 53 controls (25%) were observed in high susceptibility area; 77 cases (75%) and 146 controls (70%) located in areas of moderate susceptibility and 4 cases (9%) and 9 controls (5%) referred to areas of low susceptibility.

Conclusion:
The creation of a map of susceptibility to AP proved to be useful to assess the possible environmental exposure of NB to AP agents during pregnancy. The results, integrated into a more complex analysis, may contribute to the evaluation of potential causal links in NBs with CA.