Why do I need to hold my breath so long before a test? What if I can't?

You're asked to hold your breath for about 10 seconds before a breath test. This is because it takes a few seconds for carbon monoxide to jump from your blood to the air in your lungs.  By holding your breath for at least 10 seconds you get a more accurate reading of CO.

If you can't hold your breath for a full 10 seconds, you can start holding your breath a few seconds after the first notification beep. That way you hold your breath for a little less than 10 seconds. Your breath CO (ppm) results may be slightly lower if you don't hold your breath for the full 10 seconds.

Note: The optimal length of time for holding your breath is 10 seconds, but you must be able to hold your breath for a minimum of 8 seconds in order to obtain an accurate CO reading. If you are not able to hold your breath for 8 seconds, you should not use this device.