This was for Hailstorm_2004 's contest where we were supposed to write about one of the periodic elements.

Invisible,
Untouchable,
But a vital part
Of life all around us.

Slowly dying,
As clouds turn to black,
It fights to cleanse our lungs.

Doesn't ask for much,
But abused nonetheless.

The world slowly kills the thing
That keeps their hearts beating.