Formula One teams were told to ensure mechanics had eye protection in the pitlane after stewards found numerous breaches during the season-ending Abu Dhabi Grand Prix on Sunday.
All team managers were summoned after the race to answer allegations of team members lacking the mandatory eyewear during pitstops.
The stewards issued a later statement saying the video evidence had been in some cases insufficiently clear to prove whether a team member with an open helmet visor might have been wearing glasses.
"Notwithstanding, there were numerous examples of eye protection not being used," they said.
"The safety of team members is paramount. All teams are requested to stress the importance of eye protection for all personnel working on a car and ensure that this article is respected by all team members in the future."
No punishments were given.
The teams were notified of potential offences during the race, causing some initial concern that drivers could be penalised until the reason was explained.