IEHIAS mask area weighting: example for pesticides
- The text on this page is taken from an equivalent page of the IEHIAS-project.
This example illustrates areal interpolation using mask area weighting, in the context of a study of worker and bystander exposures to pesticides.
As part of an assessment of health risks associated with agricultural land use change (see case study report, downloadable below), estimates were required of rates of pesticide usage across two study areas in England. Estimates needed to be at small-area scale (5 x 5 km grid) to reflect local variations in crop types and pesticide applications.
The only available data were based on surveys of sample farms, aggregated to county level. More detailed data were, however, available on both crop area (from the annual farm census - the June Agricultural Returns) and land cover (from the CORINE, satellite derived land cover map of Europe). As a basis for estimating potential exposures, therefore, these data were used to help disaggregate the county-level pesticide usage data to a 5 x 5 km grid using the approach illustrated below.
East Anglia example
The following diagram illustrates the approach for disaggregating county pesticide usage to the 5x5km grid for East Anglia.
The resulting maps of herbicide, insecticide and fungicide usage for East Anglia, modelled using mask area weighting, are shown below.