Oxygen.
You create a lot of air pollution, rubber does not burn cleanly.
Carbon burn in air.
Flammable substances are those gases, liquids and solids that will ignite and continue to burn in air if exposed to a source of ignition.
This is a badly worded question, I believe "burning" requires the oxygen in air. Substances such as Phosphorus react with air to burn, and may continue this reaction when submerged. But I do not believe this is what you mean
Any substance that burns in air is likely to burn faster in pure oxygen, if all other conditions are equal.
It melts and releases toxins into the air, as all plastics do when they melt and burn.
It mixes with clouds and create acid rain.
The new substances formed when metals burn in air are called oxides. These oxides are a result of the metal reacting with oxygen in the air.
Air, iron and water will cause the iron to rust.
Whether or not a substance can burn does not depend on it being organic. So long as it is a sufficiently reactive reducing agent, it can burn. It just so happens that most such substances on Earth are organic.
It just dissipates into the air.