Environmental exposure assessment in the German National Cohort (NAKO)

We aimed to assess the exposure to multiple environmental indicators and compare the spatial variation across participants of the German National Cohort (NAKO) to lay the foundation for health analyses. We collected highly resolved German-wide data to capture the following environmental drivers: urbanisation by population density; outdoor air pollution by particulate matter (PM_2.5), nitrogen dioxide (NO₂), ozone; road traffic noise; meteorology by air temperature, relative humidity; and the built environment by greenspace and land cover. All assessed exposures were assigned to the NAKO participants based on their baseline residential addresses. The NAKO study regions ranged from highly urbanised areas (Berlin, Hamburg) to rural regions (Neubrandenburg). This large variation is reflected in the individual environmental exposures at the place of residence. In 2019, annual PM_2.5 and NO₂ levels ranged from 6.0 to 14.6 and 3.7-33.6 μg/m³, respectively. Annual mean air temperature ranged between 7.8 and 12.7 °C. Noise data was available for a subset of urban residents (22 %), of which 42 % fell into the lowest and 1.8 % into the highest category of Lden 55-59 and Lden >75 dB(A), respectively. Greenspace also showed considerable differences (Normalised Difference Vegetation Index between 0.08 and 0.84). Spearman correlation was moderate to high within the different exposure groups, but mostly low to moderate between the groups. For the first time, a comprehensive population-based dataset with high quality environmental indicators is available for the whole of Germany. Expanding the database by adding innovative indicators such as light pollution, walkability, biodiversity as well as contextual socioeconomic factors will further increase its usefulness for science and public health.