Escape from the fire! It’s easy!

Just open in case of emergency

X Just open in case of emergency

Tim says:

This sign is not quite using the word “just” correctly. That word has many meanings. The sign wants to say that people should not use the door except in an emergency situation. But when “just” is used at the beginning of a sentence, it is more likely to mean 「いいから、やってみて!」It’s easy! No problem!

It’s better to replace “just” with “only,” and to put it after the verb:

O Open only in case of emergency