Sometimes, the best ideas are the simplest. To help prevent deaths from carbon monoxide poisoning in Poland, where 100 people die every year, Grey Group Poland created a leaflet that can actually save lives.
The agency masterminded a partnership between the National Fire Service of Poland, and major Polish retailers Pepco, Lewiatan and Złote Tarasy to promote what is described in the case study as a simple "life-saving hack"--that if you hold a piece of paper over a properly working vent in your apartment, the pressure will make it stick. If it doesn't stick, it could be malfunctioning--a potential cause of carbon monoxide poisoning--and you need to get it checked out.
The retailers turned 28 million of their leaflets into "vent inspection ads" that instructed Poles how to place the leaflet on their vents--therefore potentially saving many lives.