There are many ways to identify whether there is bad breath, often used in daily life are: 1, saliva detection, wash your hands, lick the back of your hands with your tongue, with saliva to dry, you can smell the strong smell of bad breath, or wet the paper with saliva, to dry the paper and smell the bad breath. 2, breath detection, you can cover your mouth with both hands, outward breathing, if you can smell a heavy bad breath, it is bad breath. 3, tartar detection After brushing your teeth, use a toothpick or dental floss to remove the tartar from your teeth and smell carefully for bad breath odor. 4, tongue moss detection, patients with bad breath have thick tongue moss, use a clean toothbrush, gauze or wet wipes to remove part of the tongue moss, dry it and smell for bad breath odor. You can use a halitosis detector, the main component of the formation of halitosis is methyl mercaptan, mainly through the detection of the concentration of the substance to determine whether there is bad breath.