Did those raw onions on your burger leave you with a lingering odour? How about that cup of morning coffee that still makes your breath smell well into the afternoon?

Bad breath is a sensitive subject, but international breath guru Dr. Harold Katz has made it his mission to educate the masses about halitosis and stop the stench.

"Everyone is unaware of their breath. You can't smell your own breath. In this process called acclimation, your brain gets used to your own odour," said Dr. Katz, dentist and founder of California Breath Clinics. 

Dr. Katz says bad breath is no laughing matter. In fact, he knows couples who have divorced over the issue or people who have been fired from their job because of their breath.

So what causes halitosis? Blame the bacteria that are growing inside your mouth, producing volatile sulphur compounds.

“There’s hydrogen sulphide, that's the rotten egg smell. Another is called cadaverine and another is called putrescine, the smell of rotting flesh,” said Dr. Katz. 

Many foods, like onion, garlic, cabbage and brussels sprouts already contain sulphur compounds, making the problem worse. Coffee can also cause breath issues because it has acids which stimulate bacteria.

If you think mouthwashes help, think again. Dr. Katz says they contain alcohol which dries out your mouth, making breath worse. Most foaming toothpastes also contain compounds which dry out your mouth.

Dr. Katz makes his own line of breath busting products aimed at keeping the mouth wet and bacteria free. He tests the products’ effectiveness with a device called a halimeter. The halimeter detects parts per billion of sulphur compounds produced by bacteria in your mouth.

Anything over 100 and your breath can be noticed by others around you.

After using one of the TheraBreath mints consumer reporter Lynda Steele’s breath registered in at 74, a good score according to Dr. Katz.

"The analogy I always give is your mouth is the doorway to the rest of your body.  If your breath is not fresh imagine what the rest of the house smells like," he said.

Dr. Katz says another way to test your breath is to lick your hand. Sulphur compounds blend in with your saliva and once the liquid evaporates they stick to your hand, allowing you to smell your own bad breath.

Dr. Katz is also working on a disposable home kit to test your breath before a big date or job interview and he even makes a line of breath products for dogs and cats.