O2 isn't necessary for rusting, but some source of oxygen is required. Rust is just another name for iron oxide, and without oxygen there can't be oxide.
Hope this helps,
Davinia.
1.00 degree increase<span> on the </span>Celsius scale<span> is </span>equivalent<span> to a </span>1.80 degree increase<span> on the</span>Fahrenheit scale<span>. If a </span>temperature increases<span> by </span>48.0°C<span>, </span>