Dust properties in the Galactic bulge

Context. It has been suggested that the ratio of total-to-selective extinction R-V in dust in the interstellar medium differs in the Galactic bulge from its value in the local neighborhood.Aims. We attempt to test this suggestion.Methods. The mid-infrared hydrogen lines in 16 Galactic bulge PNe measured by the Spitzer Space Telescope are used to determine the extinction corrected H beta flux. This is compared to the observed H beta flux to obtain the total extinction at H beta. The selective extinction is obtained from the observed Balmer decrement in these nebulae. The value of R-V can then be found.Results. The ratio of total-to-selective extinction in the Galactic bulge is consistent with the value R-V = 3.1, which is the same as has been found in the local neighborhood.Conclusions. The suggestion that R-V is different in the Galactic bulge is incorrect. The reasons for this are discussed.