Vehicles circulating in Barcelona without the DGT environmental rating badge are now estimated to account for between 7% and 9% of traffic in the city. The data comes from the low emission zone cameras in operation during the first month. These vehicles represented 20% of traffic in 2017. The drop (40,000 fewer vehicles in circulation in the city) equates to a 19% drop in NO_x, emissions, some 684 tonnes in all.

Barcelona City Council has set up an expert committee to monitor emissions and air quality in the city by evaluating the low emission zone every six months. The evaluation is accompanied by an interactive pollution map, which can be freely viewed on the air quality website. The map will offer up-to-date information on each street section based on specific measures at the Atmospheric Pollution Monitoring and Forecasting Network stations located around the city.