Visceral and interactive, the Pollution Pods art installation gets policymakers and influencers discussing the links among air pollution, health and climate change.<br>Air quality is difficult to visualize, making it easy to forget and thus a challenge to keep at the top of people’s minds– but one artist has given it a whirl, and his exhibition, brought to the UN Headquarters this week by the World Health Organization, is generating lively discussions by its influential visitors on the links among air pollution, climate change, health and subnational action.