Are tobacco packaging warning messages improving health of society?

Question

Are there any countries with law not requiring such warnings? If yes, were there conducted any smokers-related studies?

Answer 1

There are some studied done about it. Here is the list of them

1. Effectiveness of cigarette warning labels
2. Perceived Believability of Warning Label Information
3. Do Cigarette Warning Labels Reduce Smoking?

Another study came up with

Approximately one fifth of participants [by the way there are 616 adult smokers] reported smoking less as a result of the labels; only 1% reported smoking more. Although participants reported negative emotional responses to the warnings including fear (44%) and disgust (58%), smokers who reported greater negative emotion were more likely to have quit, attempted to quit, or reduced their smoking 3 months later. Participants who attempted to avoid the warnings (30%) were no less likely to think about the warnings or engage in cessation behavior at follow-up.