Japanese has 2 main adjective types - い形容詞 and な形容詞。
I think that this makes it easy to confuse English words that end with a y (which makes an ii sound) and use them as adjectives. Here is a common example:
Can you see the mistake?
Healthy is an adjective, so it is used correctly on this sign. But...
Safety is a noun! The adjective is safe. The sign should say Healthy and Safe.
Some English adjectives do end with an ii sound:
funny, happy, friendly
But some do not!
cool, smart, weak
Have fun when you use English but... Be safe!!!