Table 6: Reddening, total-to-selective extinction, visual extinction, atomic column density ratios, and gas-to-dust ratios for sightlines in the SMC. A higher Na I/Ca II ratio implies less Ca II liberated from dust grains by destructive processes and thus a more quiescent environment. A lower ratio thus indicates a more turbulent medium where dust grains are destroyed and Ca II is released into the gas phase. The Ti depletion level  $\delta _{\rm Ti}$ gives a measure of the lock up of the refractory ion in grains. A higher Ti II/Ca II ratio indicates a stronger/harder UV field. \ensuremath {{E_{B-V}}} is corrected for foreground reddening. $R_{\rm V}$ for AzV 65 and Sk 191 from Table 7, other values for $R_{\rm V}$ (and $A_{\rm V}$) from Gordon et al. (2003).
ID AzV 456 AzV 18 AzV 214 AzV 398 AzV 65 Sk 191
EB-V (mag) [1] 0.30 $\pm$ 0.03 0.17 $\pm$ 0.01 0.16 $\pm$ 0.01 0.23 $\pm$ 0.02    
EB-V (mag) [Sect.4.2] 0.27 $\pm$ 0.07 0.17 $\pm$ 0.03 0.16 $\pm$ 0.05 0.29 $\pm$ 0.04 0.08 $\pm$ 0.04 0.06 $\pm$ 0.05
$R_{\rm V}$ [1] 2.05 $\pm$ 0.17 3.30 $\pm$ 0.38 2.40 $\pm$ 0.30 3.14 $\pm$ 0.34    
$R_{\rm V}$ [2] 2.19 $\pm$ 0.23 2.90 $\pm$ 0.42     $\sim $2.8 $\sim $2.7
$A_{\rm V}$ [1] 0.54 $\pm$ 0.06 0.55 $\pm$ 0.08 0.35 $\pm$ 0.05 0.68 $\pm$ 0.11 $\sim $0.22 $\sim $0.16
$A_{\rm V}$ [2] 0.57 $\pm$ 0.08 0.49 $\pm$ 0.11        
N(H I)/$A_{\rm V}$ ($\times $1021) [1] 7.40 $\pm$ 1.20 15.45 $\pm$ 2.33 7.08 $\pm$ 1.77 11.69 $\pm$ 3.43 - -
N(H I)/$A_{\rm V}$ ($\times $1021) [3] 7.94 22.73 18.60 10.53 46 15.7
Na I/Ca II 1.8 / 7.1 (uv) 0.60 0.95 1.0 0.17 >1.15
Ti II/Ca II 0.45 1.02 0.98 0.78 0.98 0.85
log N(Ti)/N(H) -9.4 -9.0 -8.5 -8.7 -8.8 -9.4
log  $\delta _{\rm Ti}$ [4] -2.5 -2.1 -1.6 -1.8 -1.9 -2.5
[1] Gordon et al. (2003); [2] Cartledge et al. (2005); [3] H I ATCA+PARKES survey (Stanimirovic et al. 2004,1999,2000; Staveley-Smith et al. 1997, see Sect. 4.3; [4] log (Ti/H)$_{\odot}$ = -6.9 (Asplund et al. 2005). log  $\delta _{\rm Ti}$ = log [N(Ti)/N(H)] - log (Ti/H)$_{\odot}$.

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