The distance of the place of residence to the power station is considered a proxy for environmental arsenic pollution. A residual confounding with occupational exposure cannot be ruled out.

Every place of residence held for at least 1 year since 1953, when the power plant began operating, was classified according to the distance to the plant

< 5 km, 5-10 km, > 10 km.

The cutoffs were derived from atmospheric dispersion modelling of the historical pollution pattern.

To calculate Asres1, the emission data were weighted by distance and time to estimate the immision burden of a person with respect to places of residence or work.

Note that persons living in the vicinity of the power plant had elevated urinary arsenic concentrations.