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tokens: decrement, the flattest BLR decrements (lowest-ratio) are similar to the narrow-line decrement; i.e. the lower envelope is a 45-deg line parallel to the reddening vector. The null hypothesis, that the minimum BLR decrement is independent of the NLR decrement (see for example, Fig. 2 , panel VI), is excluded at a probability p = 0.002. There is a lack of AGNs with NLR decrements steeper than the BLR decrement. Points to the right of the 45-deg line are consistent with measuring errors. Only one point lies more than two standard deviations to the lower right of the red line. For the majority of AGNs, the BLR decrement is steeper than the NLR decrement. There is no significant difference in the median NLR decrement for the AGNs with very steep BLR Balmer decrements compared with those with very flat BLR Balmer decrements. These results are consistent with the earlier findings of De Zotti Gaskell ( 1985 ) and Glikman et al. ( 2007 ). De Zotti Gaskell ( 1985 ) found that Balmer decrements for nearby AGNs were steeper for the broad lines than the narrow lines, and Glikman et al. ( 2007 ) found that, for the FIRST–2MASS red quasar survey, broad lines seem to be reddened more than the sum of broad and narrow lines. Our results strongly imply that: the dust that reddens the NLR also reddens the BLR, but most of the dust reddening the BLR lies between the BLR and the NLR. The dust causing the common reddening of both the NLR and BLR could be associated with the NLR or it could be dust in the host galaxy. De Zotti Gaskell ( 1985 ) studied nuclear continuum colours and both broad- and narrow-line Balmer decrements of nearby AGNs as a function of the orientation of the host galaxy. They found that for more highly inclined disc galaxies, the nuclear colours were redder and the Balmer decrements steeper. Since the axis of symmetry of an AGN is not necessarily aligned with the rotation axis of the galaxy (see for example, Tohline Osterbrock 1982 ; Valtonen 1983 ; Battye Browne 2009 ), the greater nuclear reddening of inclined galaxies must be due in part simply to dust in the plane of the galaxy. 4 THE RELATIVE STRENGTH OF [O <sc>iii</sc>] VERSUS THE BLR REDDENING As noted above, intervening dust not only causes reddening, but also extinction. If the dust is located between the NLR and the BLR, we would expect higher extinction of the BLR and AD to make [O iii ] stronger relative to the BLR and the continuum. 4.1 Selection of objects [O iii ] λ5007 is the strongest narrow line in the optical and the Balmer lines are the strongest broad lines. Therefore, a very large number of measurements are potentially available in the Sloan Digital Sky Survey (SDSS). Dong et al. ( 2008 ) have carefully measured Hα/Hβ ratios after subtraction of narrow lines and Fe ii , etc. Comparison of their ratios with the simple Gaussian fits of the SDSS pipeline reveals quite a few very discrepant measurements in the SDSS data base and that the difference between the Dong et al. (