How can the Carbon Monoxide detector be checked?

I am interested in a valid procedure for carrying out tests the Carbon Monoxide detector element within a typical 120v plug-in CO Alarm device. My question is next to respect to the CO detector itself not the push button test facet most units own. This only checks the electrical operation of the device not it's proficiency to detect the gas
Water smells resembling bleach!?
Answers:    if it is a plug-in unit receive an extension cord and hold it up to your car muffler beside your car running.
What does it indicate to dust dirt from...
you can buy c02 tester gas surrounded by an aresol can