Originally Posted by Faisal Pervaiz
Because fuel is part of the equation.
3 things are required to cause a fire; Oxygen, Fuel and Ignition.
If there was no fuel, then the fire couldn't begin. That's extremely important. So either of these could be mentioned, and Allah chose to mention the fuel i.e. wood.
The Qur'an is for all times and something which people be in search for when its lacking, and it has more of an effect since people can see it as a substance clearly. Whereas people take oxygen for granted. By losing fuel, people will feel more in a state of desperation in asking Allah for it. Compared to oxygen which is always present alhamdulillah.