http://wpri.com/2014/11/12/gas-stoves-can-emit-dangerous-levels-of-carbon-monoxide-nov14/
http://www.karg.com/pdf/coairfree_article.pdf
OK I am now enlightened. The 800 PPM (= death in one hour) referred to in Roy’s link is measured by a special instrument used by appliance techs. Using CO meter like mine is called “as measured” and should not be higher than 18 PPM.
When I do an inspection my concern is for CO levels in the house. Once I measured 35 PPM all through the house and 50 PPM in the furnace room (faulty HW heating boiler), most of the time I read 0. My Tacoma’s exhaust pipe emits 15 PPM. (No more garden hose from exhaust pipe to window for those who want to end it all.)
I will stand by my original statement that a properly adjusted gas appliance, old or new should have near 0 CO. My biggest concern with gas stoves is fire, not CO. Don’t use any plastic implements or cotton cloth pot holders etc, when cooking. I try to mention this when I encounter one on an inspection.