Zurich, Switzerland - Passengers on Zurich's Tram Line 2 have been criticized after failing for hours to notice that a fellow passenger had passed away.

We may finally have an answer to the question of how much attention people pay to those around them on public transport - and apparently, it's shockingly little.

The late 64-year-old passenger was found dead on the tram more than six hours after he passed away on Monday, after passengers failed to notice that anything was wrong with their fellow commuter.

As reported by local Swiss news source 20 Minuten, the man was on his way to work. His son said that his father got on the tram at 6:21 AM local time and should have arrived at his destination about 30 minutes later - sadly, he never arrived.

Neither the driver nor any other passengers noticed that something was wrong with the 64-year-old. It was only about six hours after he had passed that a woman finally noticed that something was wrong, and alerted the tram driver, who immediately called emergency services.

Sadly, though, by then it was too late to help the man, who had since died. Video footage from the Zurich transport authority showed that the man had ridden for twelve stations, then slumped down "and sat motionless", according to his son.

As it turns out, the commuter had suffered a fatal heart attack at the start of his journey, and was unable to call attention to himself.

The man's son was sad and angry that fellow passengers were too self-absorbed to notice anything was wrong, and likely missed an opportunity to get his father help in time.