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Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
∆CO2 increment and tram occupancy as (a) a function of time, and as (b) a function of tram occupancy. The error bars correspond to the difference between the maximum/minimum data and the average data of all the studied routes.