+ [(Number of trips which use trucks within a year * distance
(km) * rate of fuel consumption by truck (liter / km) * EF
index for nitrous oxide (g / km)) * GWP of nitrous oxide]
+ [(Number of trips which use trucks within a year * distance
(km) * rate of fuel consumption by truck (liter / km) * EF
index for methane (g / km)) * GWP of methane]}