Wood burner OGC
In the case of emissions from wood stoves, OGC refers to Organic Gaseous Compounds. These are molecules containing hydrogen and carbon atoms, and range all the way from light gases to heavy tars. The majority of them will be either in the gaseous or liquid phases when they leave the hot stove, but some of them will condense into tars either in the flue pipe or after they have left the chimney. Confusingly, if the OGCs condense after they have left the chimney, an environmental scientist would classify them as particulate matter. They are often adsorbed onto soot particles.
Some OGCs are known to have adverse health effects e.g benzene, acrolein, formaldehyde and polycyclic aromatic hydrocarbons (PAHs).
In other fields of air pollution, hydrocarbons are normally referred to as VOCs or Volatile Organic Compounds. Most OGCs would also qualify as VOCs.