how to measure how far dirty electricity extends out from wall

I understand how dirty electricity can be measured in a wire traveling in a wall, but how can its effect be measured away from the wall.  That seems like the most important measure.  How much does it affect a person standing, say 1 foot, 3 feet, 6 feet, etc. away from the wall with dirty electricity.  What instrument can be used for this and what units of measure are used?

We already have a plug-in Stetzerizer meter and Stetzerizer filters.

Thanks.