outlines some advice for pursing 'fear' based social campaigning, e.g. anti-smoking, drink drive.
Thinking about Charles Tilly's 'Why?', i think the key is to stop people defaulting to the convention 'it'll never happen to me' and so close the conversation an intrusive 'fear' based ad might open up. Key to keeping the conversation going is an easy next step that someone can take on the journey to fully changing their behaviour. Follow your stick with some carrot.