The result of EI uncertainty assessment is shown in Fig. 4. Average uncertainty ranged from −60% to +140%. A lower uncertainty was obtained for particulate species, including EC and OC which ranged from around −80% to +80%. For gaseous species, i.e., CO2 and CO, the uncertainty was high (from −60% to +230%). Both variations in EFs and activity data (amounts of residue burned) contributed to these wide ranges of the uncertainty. In particular, the EF of CO2 is expected to have less variation as it depends mainly on the carbon content of fuels; however, a large range of CO2 EF was also found in literature (from 790 to 1,670 g/kg RS, as shown in Table 3) which would cause the wide range of CO2 emission estimates