Addictions, except having disastrous effects on your current situation, can also significantly shorten your life. This addiction calculator that tells you how long you would live if you were addicted and how much shorter it would be compared to an average. It conerss the following substances:
To use the tool simply choose one of these from the drop-down list and enter a daily dose of respective drug and your age when the habit is picked up. If you want to base it on life expectancy in your country life expectancy in your country, Wikipedia comes to the rescue, as always.
The calculator is based on data aggregated and reasoning conducted by Treatment4Addiction. They took data from U.S. Centers for Disease Control and Prevention (CDC), Substance Abuse and Mental Health Services Administration and other sources.
I imagine there are small areas where you could say "wait, but", such as the one where they dismiss the fact that average life expectancy includes addicts (and people who died at an early age) or the fact that shorter lifespan isn't only related to health issues (also to accidents, crime-related deaths). Also, it's just statistical data - particular cases might be far from an average.
The calculator is meant to raise awareness around the gravity of the problem. Please feel free to fill in the numbers and share the "link to this result" on Facebook or Twitter.