The gas in galaxies is both the fuel for star formation and a medium that attenuates the light of the young stars .
We study the relations between UV attenuation , spectral slope , star formation rates , and molecular gas surface densities in a sample of 28 z \sim 1 and a reference sample of 32 z \sim 0 galaxies that are detected in CO , far-infrared , and rest frame UV .
The samples are dominated by disc-like galaxies close to the main SFR–mass relation .
We find that the location of the z \sim 1 galaxies on the IRX- \beta plane is correlated with their gas-depletion time-scale \tau _ { dep } and can predict \tau _ { dep } with a standard deviation of 0.16 dex .
We use IRX- \beta to estimate the mean total gas column densities at the locations of star formation in the galaxies , and compare them to the mean molecular gas surface densities as measured from CO. We confirm previous results regarding high N _ { H } / A _ { V } in z \sim 1 galaxies .
We estimate an increase of the gas filling factor by a factor of 4–6 from z \sim 0 to z \sim 1 and a corresponding increase of factor 3–2 in the mean column densities of the star forming clouds .
After accounting for the filling factor , the z \sim 1 and the z \sim 0 samples exhibit similar attenuation properties .
These indicate to similar porous geometries to the molecular clouds in star-forming disc galaxies at 0 < z \lesssim 1 .