Smoldering Blocks in Nether (In Addition to Fire)

In nature, many materials do not burn well, and let off a lot of smoke. Some smoke is poisonous, and all smoke can have bad effects on health if too much is breathed in. My suggestion for implementing this in Minecraft is to make some blocks give off colored smoke when lit, rather than fire. The smoke they give off would give players standing above or too close to the block negative potion effects, like poison or slowness.