The police in Plovdiv have launched an investigation after a video circulated on social media.
The footage shows a man stopping two young men in a car and claiming they were breathing laughing gas. The incident happened on Monday and became known on social media after athlete Valentin Petrov posted the footage on his profiles.
He explains that he saw the driver of the car breathing a balloon. The video also shows that the driver is on probation and was detained for 72 hours just a week ago.