February 2026
We’re pleased to share our new publication in the International Journal of Population Data Science: “Cleaning and Validating Longitudinal Postcode Histories for Environmental Epidemiology.”
As part of the PCNIC study (Air Pollution, Housing and Respiratory Tract Infections in Children), we developed a robust method for cleaning and validating residential address histories for mothers and children using national NHS administrative data in England.
While postcode cleaning may seem technical, it’s essential for producing accurate environmental exposure estimates. Environmental health research often relies on where people live to assess exposures such as air pollution, temperature, green space, or deprivation. Incomplete or inaccurate address histories can misclassify exposure and bias study findings.
Although similar work exists in Scotland, Wales, and some cohort studies in England, there has been little guidance on doing this at a national scale using routine NHS data. Our approach demonstrates a practical way to build reliable residential histories across pregnancy and early childhood.
We outline common challenges—missing or implausible dates, duplicates, invalid postcodes, and inconsistencies across data sources—and explain how we addressed them. After cleaning the data, we found that around half of children moved during infancy and about one third of mothers moved during pregnancy, highlighting how common residential change is during these periods and why it must be accounted for in exposure assessments.
We hope our methods and recommendations support other researchers working with postcode history data and help strengthen environmental health research across the UK.
