Thesis: The three chapters of” this dissertation aim at better understanding the effectiveness of pollution mitigation policies on the one hand, and who contributes to pollution at the sectoral and individual level, on the other hand. The first chapter examines the effectiveness of a carbon tax introduced on the UK power sector in 2013. Using the Synthetic control method, I estimate that the tax led to a decrease in UK emissions by between 20.5 and 26 percent on an average year between 2013 and 2017, depending on the assumptions made for potential confounding factors. The second chapter comes from an article jointly written with Léo Zabrocki and Marie- Abéle Bind. We examine the contribution of cruise vessels to air pollution in Marseille in a context of rising concerns over their effects on pollution and health. We create hypothetical randomized experiments where only cruise vessel traffic varies. We find that the arrival of cruise vessels in the port increases hourly and daily concentrations of sulphur dioxide and particulate matter. The third chapter comes from an article jointly written with Philippe Quirion, and examines transport-induced local and gIobaI pollution in the Paris area. We find that 20% of emitters contribute 73-85% of emissions, depending on the pollutant. We explain differences in emissions across individuals using an exact decomposition analysis and regression analysis. We estimate that a realistic scenario of modal shift away from cars, built counterfactual travel time data, could save around 20% of total emissions.