contents   index   previous   next

Spatial Risk Issues


SADA will convert any geospatial estimation map into a geospatial risk map. This conversion is performed by using each modeled block concentration value as the exposure concentration in the risk models.


From a risk standpoint, individual block risk may not provide useful information, especially for small block sizes. The scenario parameters often assume the receptor will be exposed to the contaminant over a number of years. This translates into an assumption that the individual will be exposed to a single block for a number of years and/or a large portion of the day. For small block sizes (e.g., 1ft x 1ft), this is not reasonable.


The spatial risk map does, however, provide useful information from a decision standpoint. With the risk map visible, areas of concern are more easily identified. These areas can then be captured within a reasonable exposure unit size by polygons. By pressing the Statistics button on the main toolbar, the average risk over these blocks in the polygon is calculated. Note: this corresponds to averaging the block concentration values for the polygonal area and applying the result to the risk models.


Spatial risk maps play important roles in other decision frameworks, as well. For an explanation of how to view risk maps and how they are used in decision making, see Risk Maps.