Canaries in the coal mine.

Up until 30 years ago, coalminers relied on canaries as warning systems against harmful gases and pollutants underground. The miners listened for birdsong and if the birds fell silent, then they knew there was danger to their health and to take action. Today we have much more sophisticated information and reporting on the quality of air. We know precisely the levels and composition of pollutants in the air that are responsible for almost 500,000 deaths annually [1]. The problem is however, that nobody appears to be listening.