Process for determining an amount of pollutant emissions from a vehicle, said vehicle having an internal combustion engine and a system for aftertreatment of the exhaust gases of said engine, wherein at least one macroscopic parameter (PAR) relating to the design of said vehicle is acquired from a database which lists the various vehicles in circulation, said at least one macroscopic parameter being chosen from: the type of motorization, the certification standard, the engine swept volume, the maximum torque and the rating of the associated engine, the maximum power and the rating of the associated engine, the weight of the vehicle, the type of transmission of the vehicle, the type of aftertreatment system, the type of injection system, the architecture of the air loop, and wherein the following are constructed for said vehicle: i) a model of said vehicle (MOD VEH) which connects said position and the altitude and the speed of said vehicle to the torque and to the rating of said engine by means of at least one macroscopic parameter (PAR); ii) a model of said engine (MOD MOT) which connects said torque and said rating of said engine to the pollutant emissions leaving said engine by means of at least one macroscopic parameter (PAR); and iii) a model of said aftertreatment system (MOD POT) which connects said pollutant emissions leaving said engine by means to the pollutant emissions leaving said aftertreatment system by means of at least one macroscopic parameter (PAR); characterized in that the following steps are carried out by means of a mobile phone: a) the position (pos GPS ) and the altitude (alt GPS ) and the speed (v GPS ) of said vehicle are measured; b) said torque (Cme) and said rating (Ne) of said engine are determined by means of said vehicle model (MOD VEH) and said measurements; c) the pollutant emissions leaving said engine (PSME) are determined by means of said engine model (MOD MOT) and said torque (Cme) and said rating (Ne) of said engine; and d) at each instant or for a journey which has been made, an amount of the pollutant emissions from the vehicle (PSEE) is determined by means of said aftertreatment system model (MOD POT) and said pollutant emissions leaving said engine (PSME). i) a model of said vehicle (MOD VEH) which connects said position and the altitude and the speed of said vehicle to the torque and to the rating of said engine by means of at least one macroscopic parameter (PAR); ii) a model of said engine (MOD MOT) which connects said torque and said rating of said engine to the pollutant emissions leaving said engine by means of at least one macroscopic parameter (PAR); and iii) a model of said aftertreatment system (MOD POT) which connects said pollutant emissions leaving said engine by means to the pollutant emissions leaving said aftertreatment system by means of at least one macroscopic parameter (PAR); a) the position (pos GPS ) and the altitude (alt GPS ) and the speed (v GPS ) of said vehicle are measured; b) said torque (Cme) and said rating (Ne) of said engine are determined by means of said vehicle model (MOD VEH) and said measurements; c) the pollutant emissions leaving said engine (PSME) are determined by means of said engine model (MOD MOT) and said torque (Cme) and said rating (Ne) of said engine; and d) at each instant or for a journey which has been made, an amount of the pollutant emissions from the vehicle (PSEE) is determined by means of said aftertreatment system model (MOD POT) and said pollutant emissions leaving said engine (PSME). <EOS>