In a message dated 97-10-29 12:51:20 EST, you write:

<<
 It's that time of the year that Carbon Monoxide can become dangerous.
  Ideal project for a PIC.  Problem, where can you get Carbon Monoxide
 detectors?

 Steve
 sdavidson@its.bldrdoc.gov >>

Hello Steve,
I saw a Popular Electronics (Or was it the other one) article that did this
with those $5.00 disposable cards that are available at most hardware stores.
 They have a chemically sensitive spot on them that turns color when exposed
to CO.  The article used a photo sensor and a light source to detect the
color change.  The only drawback is you have to replace the card once it has
been exposed.

Dave Duley