未然(みぜん)before it happens, previously

事故(じこ)を未然(みぜん)に防(ふせ)ぐことが大切(たいせつ)です。

It is important to prevent accidents before they happen. {before it happens, previously}

災害(さいがい)を未然(みぜん)に防(ふせ)ぐために対策(たいさく)をしています。

We are taking measures to prevent disasters before they happen. {before it happens, previously}

青少年(せいしょうねん)の非行(ひこう)を未然(みぜん)に防(ふせ)ぐために支援(しえん)をする。

We provide support to prevent juvenile delinquency before it happens. {before it happens, previously}

素早(すばや)い消火(しょうか)器(き)の使用(しよう)が大(だい)規模(きぼ)な火事(かじ)を未然(みぜん)に防(ふせ)いだのだ。

The swift use of fire extinguishers prevented a large-scale fire before it happened. {before it happens, previously}

事故(じこ)を未然(みぜん)に防(ふせ)ぎたいのなら、事故(じこ)に対(たい)する対策(たいさく)を講(こう)じるべきだ。

If you want to prevent an accident before it happens, you should take measures against it. {before it happens, previously}