Substances that contribute to the formation of ozone in the lower atmosphere. Including:

• Non-methane Volatile Organic Compounds (NMVOC) : These are all organic compounds, other than methane, resulting from human activities that are capable of producing photochemical oxides by reactions with nitrogen oxides in the presence of sunlight (DIRECTIVE 2001/81/EC of the European Parliament and the Council of 23 October 2001, on national emission ceilings for certain atmospheric pollutants). Expressed in mass units (kg)
• Carbon Monoxide (CO): Expressed in mass units (kg)