No laughing matter: Manchester United ace Mason Greenwood apologizes as 'historical' footage of him using LAUGHING GAS emerges

Manchester United's teenage forward Mason Greenwood has landed in the the headlines again, this time after images of him using nitrous oxide, better known as "laughing gas," were published in UK media.

Greenwood, who was sent home from Gareth Southgate's England squad last week with Phil Foden after breaking quarantine protocols following a 1-0 win away to Iceland, says that he apologizes for his "poor judgment" after a video of him appearing to inhale the gas from a balloon was published by The Sun.

"I strongly urge others not to follow my example," Greenwood said in response to the reports.

"I have now been made aware of the health risks associated with this practice and accept that even trying it, as shown in these historical pictures, was poor judgment on my part."

Nitrous oxide, otherwise known as "laughing gas" or "hippy crack," is a legally sold substance for use in medical or commercial fields and while it is not illegal to possess it, it is illegal to distribute it as a psychoactive substance. 

The effects of the gas often produce feelings of euphoria, and slows the brain's responses. It can also incite hallucinations and cause headaches and paranoia. 

"As an 18-year-old, I am learning all the time," Greenwood continued.

"However, this week I have also learned I will be judged to a higher standard because of my career as a footballer and I must respect that in future.

"I am determined to repay the faith shown in me by my manager and coaches."

Greenwood, who scored 17 goals last season for Manchester United, earned his first England cap in last week's 1-0 win away to Iceland but was heavily criticized in the wake of the game amid reports that he and Foden invited women back to the team hotel - failing to adhere to the team's quarantine protocols. 

Both players were subsequently sent home and were absent for the subsequent 0-0 draw with Denmark. Greenwood said that he "only had himself to blame" for the incident, and has since returned to Manchester United training - where he is undertaking physical activities in isolation due to COVID-19 protocols.