The first vape shop of Braintree celebrates three years in the shopping street.
Charlie Charalambous opened Dampen in 2015 after the use of electronic cigarettes to stop smoking herself.
Since then, he believes he has helped hundreds of smokers to attack the habit.
In collaboration with the healthcare company Provide, the store now offers the 28-day challenge for carbon monoxide.
This is where people who want to quit smoking do a CO test on the first day to quit and then on day 28 to see how much they have dropped.
Mr. Charalambous said: "This is a great incentive to persuade people to stop.
"Sometimes people need a mental goal to follow, which gives that little extra willpower.
"It's also nice for myself when I see people succeed and the look on their face when they realize their sense of satisfaction."
Mr. Charalambous said that he had been grateful to all his customers for the past three years and is looking to help more people stop in the future.