1. INTRODUCTION  
2. METHOD  
2.1. From UV slope to optical depth  
2.2. From optical depth to dust mass  
3. RESULTS  
3.1. Milky Way extinction curve  
3.2. General trends  
4. ADDITIONAL IMPLICATIONS  
4.1. [CII] line luminosity – SFR relation  
4.2. Burstiness gas depletion time  
5. WHERE THE IRX RELATION FAILS  
6. SUMMARY