[orangecat]

The actual numbers matter. Suppose vaping is 20% as harmful as smoking, and out of every 100 children, the availability of e-cigarettes causes 5 to switch from smoking to vaping and 5 others to start vaping who wouldn't have started smoking. That would be a substantial improvement.

[magissima]

Those aren't actual numbers though, nor is "percentage of harmfulness" directly quantifiable.