First of all, please be very careful about the sources of your carbon
monoxide (the car exhause also contains carbon monoxide), and it is fairly
lethal, even in small concentrations.
Insofar as monitoring equipment, there is a lot of it on the market, but
none of it is cheap, either to buy or rent. You may want to try your
local safety supply store, as they may carry MSA (brand) detectors which
will "live-time" analyze for CO2 and CO. If you are only going for
periodic monitoring, you might try a call to the closest environmental
engineering firm to see if they have a Draeger set. This is a device that
uses expendable tubes to do a one-time monitoring of different
constituents. You may also be able to get help r.e. instrumentation from
your local fire department, who will certainly have the type of monitoring
equipment you need.
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