Just as illiteracy relates to words, innumeracy relates to numbers.  It’s also the title of a book by John Allen Paulos.

One funny example he gives in the book is that of a high school math teacher who is teaching about very small numbers.  He assigns the task for his pupils to find out how fast their hair grows, in miles per hour.  One boy grew frustrated, finally calling out “Hair doesn’t grow in miles per hour!”.

In today’s real-life example, our plumber told us that the state code for water filtration is 5 microns, but he’s doing something twice as good – 10 microns!  ‘Tain’t so.  10 microns lets particles twice as big as the 5 micron filter, which is going the wrong direction.  And all you can talk about is particle size, not “goodness”.  If the state code says 5 microns, and the E. Coli/anthrax mutant comes in at 7 microns, then the 10 micron filter doesn’t help at all.  It’s not twice as good.  It’s not half as good.  It’s no good at all.

And besides, I think that Ohio Health Code section 3701-28-09, paragraph (E), clause (b) applies (yes, that’s the real section/paragraph/clause).

(E) An ultraviolet light system used as the primary means of disinfection shall also meet the following criteria:

(b) An absolute filter size of one to two microns shall be installed prior to treatment of the water by the ultraviolet equipment.