**5. Conclusions**

This study showed the importance of stratifying an environmental burden of disease study on the socioeconomic level in order to take into consideration the modifier effect of socioeconomic status on the air pollution-mortality relationship. In addition, we demonstrated the value of spatial analysis to guide decision-making. Indeed, given today's budgetary constraints, it can be quite challenging for policymakers to select an initiative. This shows the need for tools to support priority-setting and to guide policymakers in their choice of environmental initiatives that would maximize health gains and reduce social inequalities in health.

**Author Contributions:** Conceptualization, W.K.-T. and S.D.; Formal analysis, W.K.-T., P.L. and S.D.; Investigation, W.K.-T., P.L., P.L.N. and S.D.; Methodology, W.K.-T., P.L., P.L.N. and S.D.; Supervision, W.K.-T. and S.D.; Validation, W.K.-T. and S.D.; Writing—original draft, W.K.-T., P.L., P.L.N. and S.D.; Writing—review & editing, W.K.-T. and S.D.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors thank all scientific researchers of the Equit' Area project and the personnel of the local association in air quality of Paris Metropolitan Area. This study was supported by Foundation de France and Interdisciplinary research program on health crises and health protection of University of Sorbonne Paris City (U.S.PC).

**Conflicts of Interest:** The authors declare they have no actual or potential competing financial interests.

**Appendix A.**

**Figure A1.** Spatial distribution of the exceeded the WHO threshold of annual average level of NO2 from 2000–2009 (the difference between level of NO2 exposure in each census block and WHO guidelines (40 μg/m3)).

*Int. J. Environ. Res. Public Health* **2019**, *16*, 38


**Figure A2.** Spatial distribution of the exceeded the WHO threshold of annual average level of PM10 from 2000–2009 (the difference between level of PM10 exposure in each census block and WHO guidelines (20 μg/m3)).


**Figure A3.** Spatial distribution of the exceeded the WHO threshold of annual average level of PM2.5 from 2000–2009 (the difference between level of PM2.5 exposure in each census block and WHO guidelines (10 μg/m3)).

**Figure A4.** Spatial distribution of the rate of deaths attributable to PM10 among total death, at the census block level, Paris City; (**a**) without spatial variability of PM10 exposure in Paris; (**b**) with spatial variability of PM10 between census block; (**c**) with spatial variability of PM10 and socio-economic level between census block.

*Int. J. Environ. Res. Public Health* **2019**, *16*, 38

**Figure A5.** Spatial distribution of the rate of deaths attributable to PM2.5 among total death, at the census block level, Paris City; (**a**) without spatial variability of PM2.5 exposure in Paris; (**b**) with spatial variability of PM2.5 between census block; (**c**) tacking account the spatial variability of PM2.5 and socio-economic level between census block.
