When a radio or TV show is on-air, it is going out to people right now. The red ON AIR light in a studio means: we are sending the programme; do not walk in and talk.

When a radio or TV show is on-air當一個電台或電視節目 on-air 的時候，it is going out to people right now它此刻正向大家播送出去。in a studio攝影棚裡 The red ON AIR light那盞紅色的 ON AIR 燈 means意思是：we are sending the programme我們正在送出節目；do not walk in and talk別走進來說話。

You will also see it before a noun: an on-air interview, an on-air job (talking on radio or TV for a living). People go on air when they start, and go off air when they stop.

You will also see it你也會看到它 before a noun出現在名詞前面：an on-air interview一場播出中的訪問、an on-air job一份在電台或電視上說話的工作 (talking on radio or TV for a living靠在電台或電視上說話維生)。People人們 when they start開始播的時候 go on air說 go on air，and when they stop停下來的時候 go off air說 go off air。

Though actually, on-air and live are not always the same thing. A show can be on-air this minute but recorded yesterday. On-air only says it is going out; live says it is happening at the same time you hear it.

Though actually不過實際上，on-air and live on-air 和 live are not always the same thing不一定是同一回事。A show一個節目 can be on-air this minute可以這一分鐘正在播出，but recorded yesterday卻是昨天錄好的。On-air only says只說 it is going out它正在播送出去；live says說的是 at the same time you hear it在你聽到的同一時刻 it is happening事情正在發生。

Everyday English when you talk about radio and TV; inside a station, people use it all day.

when you talk about radio and TV談到電台和電視時，Everyday English這是日常英文；inside a station在電視台、電台裡面，people use it all day人們整天都在用它。