*3.3. Spatial Distribution*

The rate of "premature" deaths per census block (Figure 3) was estimated according to 3 different scenarios: (a) without spatial variability of NO2 in Paris, (b) with spatial variability of NO2 between census blocks, and (c) with spatial variability of NO2 and socio-economic level between census blocks. The rate corresponds to the number of premature death divided by the number of total adult deaths.

Unlike the Figure 3a, the Figure 3b,c reveal a spatial pattern with a higher rate of "premature" deaths attributable to NO2 located in the north part of Paris in comparison with the south part. A difference also appears between Figure 3b,c: considering the spatial variability of NO2 combined with the level of socio-economic deprivation (based on Dutch study [14]), the higher rate of "premature" deaths among total adult death shifted in northeastern Paris (Figure 3c).

For particulate matter, the spatial distribution of the rate of the "premature" adult deaths attributable to PM10 and PM2.5, respectively, among total death, show the same pattern (see Appendix A Figures A4 and A5).

**Figure 3.** *Cont.*

**Figure 3.** Spatial distribution of the rate of adults deaths attributable to NO2 among total death, at the census block level, Paris city; (**a**) without spatial variability of NO2 exposure in Paris; (**b**) with spatial variability of NO2 between census blocks; (**c**) with spatial variability of NO2 and socio-economic level between census blocks (according Dutch study [14]).

The statistical spatial approach confirms that the spatial aggregation of "premature" deaths in the northeast is significant (see Figure 4). This means that "premature" deaths are not randomly distributed across the study area. This most likely cluster comprises an area of 459 census blocks with a risk 1.12 times higher than in the rest of the study area (*p*-value = 0.029). This cluster hosts a total of 4,038,108 inhabitants and has 3455 "premature" deaths (about 80% of the total number of "premature" deaths estimated in Paris). The spatial approach did not reveal any statistically significant aggregation of "premature" deaths attributable to PM10 and to PM2.5 (data not shown).

**Figure 4.** Mapping of the most likely cluster of the number of avoidable deaths. Blue areas identify census block included in the most likely cluster.
